METHOD AND SYSTEM FOR CONTROLLING A POWER ENGINE COOLING SYSTEM

Abstract

Procedure that includes the following: Estimating a fluid level (1710, 1720, 1730, 1740) in a coolant reservoir based on a sensor coupled into a vertical standpipe (210, 310, 1304) aligned parallel to the coolant reservoir, wherein the standpipe (210, 310, 1304) is fluidically coupled to the coolant reservoir at both an upper and a lower location; and Limiting engine power based on the estimated fluid level (1710, 1720, 1730, 1740).

Description

Area

[0001] The present application relates to methods and systems for inferring a fluid level in a coolant overflow tank (or degassing bottle) and for adjusting the engine operation based on a fluid level estimated in a vertical hollow standpipe fluidically coupled to the overflow tank. Background and Summary

[0002] Vehicles may contain cooling systems configured to reduce engine overheating by transferring heat to the surrounding air. In these systems, coolant circulates through the engine block to remove heat from the engine, and the heated coolant then circulates through a radiator to dissipate the heat. The cooling system may include various components, such as a coolant reservoir coupled to the system for degassing and storing the coolant. A pressurized container, which also serves to separate entrained air from the coolant, is typically called a degassing bottle. If the coolant temperature rises anywhere in the system, the thermal expansion of the coolant causes the pressure in the degassing bottle to increase as the volume of trapped air decreases.Pressure relief can be achieved by releasing air from the degassing cylinder through a valve, typically located in the filling cap. Then, when the temperature and pressure of the refrigerant in the degassing cylinder fall below atmospheric pressure, air can be drawn back into the cylinder through another valve, often located in the filling cap.

[0003] If the coolant level in the bottle is too low, the air volume is too large to build up sufficient pressure to prevent boiling and cavitation at the water pump inlet. At low fluid levels, the degassing bottle is also no longer able to separate the air from the coolant, and the air can be drawn into the cooling system, again resulting in poor cooling performance. If an overflow system is used instead of an active degassing system, a similar loss of cooling system performance can occur when fluid levels are low.

[0004] Several approaches can be used to estimate the fluid level in a container. One example, described by Murphy in US 8,583,387 B2, uses an ultrasonic fluid level sensor installed at the bottom of the container to estimate the fluid level. However, the inventors recognized that in such a cooling system, the dimensions of the coolant reservoir can vary based on the temperature of the coolant contained within. As a result, inconsistencies in the estimated coolant level can occur. Furthermore, due to the sensor's location at the bottom of the container, it can be unclear whether the fluid level is low or the container is empty when coolant levels are low. Even more significantly, it can be difficult to distinguish between a true low coolant level and an erroneous estimate due to sensor degradation.In another exemplary approach, described by Gordon et al. in US 2013 / 0103284A1, the sensor is coupled to a hose of the coolant reservoir. A problem with this approach is that the sensor can only detect the presence of coolant at that location in the circuit. Critical powertrain components may not receive coolant regardless of the presence of coolant in one of the coolant reservoir hoses, especially if that hose is isolated from the cooling system by a valve (e.g., the engine thermostat hose). Furthermore, while a low coolant level reading is received, engine temperature control may already be impaired due to significant coolant loss in the reservoir. US 5,765,433A discloses a fluid level measurement system. JP S56-61619A discloses an ultrasonic level sensor.FR 1 250 563 A discloses a device for indicating the fill level of a liquid in a container. DE 10 2010 017 766 A1 discloses a cooling arrangement for internal combustion engines. DE 103 12 102 A1 discloses a device for measuring the fill level of a liquid in a container.

[0005] In one example, the problems mentioned above can be at least partially addressed by a procedure for a coolant system, the procedure comprising: estimating a fluid level in a coolant reservoir based on a sensor coupled to a vertical standpipe aligned parallel to the reservoir, the standpipe being fluidically coupled to the reservoir at both an upper and a lower position; and limiting engine power based on the estimated fluid level. In this way, changes in the coolant level state based on transient changes in the estimated coolant level can be mitigated, allowing for appropriate measures to be taken to prevent engine overheating when the coolant level state is low compared to empty, or if the sensor has been disturbed or degraded for longer than a threshold duration.

[0006] As an example, a power engine coolant system may include a vertical pipe directed towards a coolant overflow tank, with the pipe housing an ultrasonic sensor. The vertical pipe may be connected to the coolant tank at both its upper and lower ends via hoses, with the coolant flowing between the pipe and the tank. The hoses may be connected to create a gas space between the surface of the fluid level in the vertical pipe and the top of the pipe. Furthermore, the hoses may be connected so that the top of the vertical pipe is positioned at a lower height than the top of the coolant tank, allowing the sensor to more reliably estimate the fluid level in the tank and more reliably distinguish between low and empty coolant levels.The sensor, positioned within a recess at the bottom of the vertical pipe, can send a signal to the top of the pipe. An echo of this signal is received at the sensor after it has been reflected from the top of the pipe. The signal can be sent periodically, allowing the coolant level in the vertical pipe to be estimated based on an average echo time (the time elapsed between sending the signal and receiving its echo). This estimate can then be used to infer the coolant level in the reservoir. Changes in the coolant level state can then be implemented based on changes in the fluid level of the coolant reservoir during a threshold period. This ensures that the coolant level state is only updated after the fluid level estimate has stabilized.Diagnostic codes can be set based on the coolant level. Furthermore, engine power can be limited to varying degrees based on the coolant level. For example, in response to a low coolant level indication, an initial diagnostic code can be set, limiting the engine load by a certain amount to reduce engine overheating. Additionally, fuel injection can be disabled for a period of time to reduce the amount of heat transferred to the engine coolant. The initial diagnostic code can be cleared upon completion of the key cycle.If the time elapsed since entering the first diagnostic mode exceeds a threshold and the coolant level is still low or has changed to EMPTY, a second diagnostic code may be set, and engine power may be limited by a second, larger amount. In the second diagnostic mode, the engine may, for example, be forced to idle. Furthermore, the second diagnostic code cannot be cleared until the vehicle is taken to a service technician and a dealer code has been entered.

[0007] In this way, the accuracy and reliability of determining the coolant level of a coolant overflow tank can be increased. By inferring the tank's coolant level based on an estimated coolant level in a standpipe coupled to the tank, inaccuracies in coolant level estimation due to distortion of the tank's sensor output caused by thermal fluctuations or vehicle movement are reduced. Selectively updating the coolant level status of the coolant overflow tank based on changes in the standpipe's coolant level reduces the frequency and erratic estimation of the coolant level. Furthermore, it reduces the unintentional triggering of a powertrain fault mode. This, in turn, reduces the frequency with which powertrain output is unnecessarily limited.By relying on an ultrasonic sensor and the local processor to estimate the standpipe coolant level based on an echo time, the coolant level estimation can be accelerated. Overall, this can reduce engine overheating caused by inaccurate coolant level estimation.

[0008] It should be self-evident that the above summary is provided to introduce, in simplified form, a selection of the concepts that are further described in the detailed description. It is not intended to identify key or essential features of the claimed subject matter, the scope of which is clearly defined by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that eliminate all the disadvantages stated above or in any part of this disclosure. Brief description of the characters Fig. Figure 1 shows a power engine system that includes a power engine cooling system. Fig. Figure 2 shows a block diagram of a power engine cooling system. Fig. Figure 3 shows part of an exemplary cooling system which includes a coolant reservoir which is fluidically coupled to a standpipe, the standpipe being attached to the vehicle frame. Fig. Figure 4 shows an alternative view of the part of the cooling system in Fig. 3, which highlights the features of fluid coupling and the attachment of the standpipe. Fig. Figure 5 shows a second alternative view of the part of the cooling system in Fig. 3. Fig. Figure 6 shows a third alternative view of the part of the cooling system in Fig. 3, which highlights the attachment of the standpipe to the vehicle frame. Fig. Figure 7 shows a fourth alternative view of the part of the cooling system in Fig. 3, which highlights an ultrasonic level sensor inside the standpipe and the attachment of the standpipe to the vehicle frame. Fig. Figure 8 shows a lid configured to fit the top of a vertical standpipe. Fig. Figure 9 shows a high-order flowchart for estimating the fluid level in the coolant reservoir. Fig. Figure 10 presents an exemplary method for adjusting the amount of power supplied to an ultrasonic level sensor in a vertical standpipe of a cooling system. Fig. Figure 11 presents an exemplary method for estimating a fluid level in a vertical standpipe based on information from an ultrasonic level sensor. Fig. Figure 12 presents an exemplary method for estimating a fluid level in a vertical standpipe based on the echo times and an estimate of the fluid composition. Fig. Figures 13A-13C show the divergence of fluid levels in the vertical standpipe and the coolant reservoir based on the position of the vehicle. Fig. 14 presents an exemplary procedure for determining a sloshing term and for setting an estimate of the standpipe fluid level based on the sloshing term. Fig. Figure 15 presents an exemplary method for detecting the deterioration of an ultrasonic level sensor based on the accumulated sloshing terms. Fig. 16 presents an exemplary control system for determining a sloshing term and for setting an estimate of a coolant volume level based on the sloshing term. Fig. Figure 17 shows four cases of sloshing within a standpipe compared with the predicted amounts of sloshing. Fig. Figure 18 presents an exemplary procedure for determining a coolant level based on comparing an estimate of the coolant volume level with different threshold values. Fig. 19 represents the determination of a coolant condition based on a history of coolant levels and coolant conditions. Detailed description

[0009] The following description refers to systems and methods for controlling a vehicle's engine, wherein the engine has a cooling system, such as that described in the Fig. 1-2. The cooling system may include a coolant overflow tank, also referred to here as a degassing bottle, which is fluidically connected to a narrow vertical standpipe, as in the Fig. 3-8 is discussed. The vertical standpipe can contain a level sensor that transmits information to a power machine controller to determine the quantity of coolant within the standpipe, as described in the Fig. 9-12 is elaborated. The controller can also estimate the amount of coolant within the degassing bottle (also referred to here as the coolant volume level) based on the amount of coolant within the standpipe (also referred to here as a local coolant level) and various motion parameters, as described in the Fig. 13-17. Based on the coolant estimate, the controller can specify a coolant state, whereby restrictions can be imposed on the operating parameters of the engine based on the coolant state, as described in the Fig. This is discussed in sections 18-19. In this way, coolant volume levels can be inferred more accurately even during sloshing events. Furthermore, low coolant levels can be detected more reliably, and the engine's operating parameters can be restricted accordingly to prevent overheating.

[0010] Fig. Figure 1 shows an exemplary embodiment of a vehicle system 100, which includes a vehicle cooling system 101 in a motor vehicle 102. The vehicle 102 has drive wheels 106, a passenger compartment 104 (also referred to here as a passenger cabin), and a compartment 103 under the engine hood. The compartment 103 under the engine hood can accommodate various components under the (not shown) engine hood of the motor vehicle 102. For example, the compartment 103 under the engine hood can accommodate an internal combustion engine 10. The internal combustion engine 10 has a combustion chamber that can receive intake air via an intake port 44 and that can discharge the combustion gases via an exhaust port 48. The engine 10, as illustrated and described here, can be included in a vehicle, such as a road vehicle, among other vehicle types.While the exemplary applications of the power machine 10 with respect to a vehicle are described, it should be recognized that various types of power machines and vehicle propulsion systems can be used, including passenger cars, trucks, etc.

[0011] The compartment 103 under the engine hood can further include a cooling system 101 that circulates the coolant through the internal combustion engine 10 to absorb the waste heat and distributes the heated coolant via coolant lines (or loops) 82 and 84, respectively, to a radiator 80 and / or a heater 90. In one example, the cooling system 101 can be coupled to the engine 10 and can circulate the engine coolant from the engine 10 via an engine-driven water pump 86 to the radiator 80 and back to the engine 10 via the coolant line 82, as shown. The engine-driven water pump 86 can be coupled to the engine via a front-end accessory drive (FEAD) 36 and rotated proportionally to the engine speed via a belt, chain, etc.Specifically, the pump 86, driven by the engine, can circulate the coolant through the channels in the engine block, head, etc., to absorb the engine heat, which is then transferred to the ambient air via the radiator 80. In an example where the pump 86 is a centrifugal pump, the pressure (and the resulting flow) generated by the pump can be increased by increasing the rotational speed of the crankshaft, which in the example is shown below. Fig. 1 can be directly linked to the engine speed. In some examples, the pump 86 driven by the engine can operate to circulate the coolant through both coolant lines 82 and 84.

[0012] The coolant temperature can be regulated by a thermostat 38. The thermostat 38 can include a temperature sensing element 238 located at the junction of coolant lines 82, 85, and 84. Furthermore, the thermostat 38 can include a thermostatic valve 240 located in coolant line 82. As described in Fig. 2. As detailed below, the thermostatic valve can remain closed until the coolant reaches a threshold temperature, thereby limiting the coolant flow through the radiator until the threshold temperature is reached.

[0013] The coolant can flow through coolant line 84 to the radiator 90, where heat can be transferred to the passenger compartment 104. The coolant then flows back to the engine 10 through valve 122. Specifically, the radiator 90, configured as a water-to-air heat exchanger, can exchange heat with the circulating coolant and transfer the heat to the vehicle's passenger compartment 104 based on the operator's heating requirements. The radiator can also be connected to the vehicle's HVAC (heating, ventilation, and air conditioning) system, which includes other components such as a heater fan and an air conditioner (not shown).

[0014] Based on the cabin heating / cooling request received from the operator, the HVAC system can heat the cabin air using the heated refrigerant in the radiator to increase cabin temperatures and provide cabin heating. One or more (not shown) fans and cooling fans may be included in the cooling system 101 to provide airflow assistance and to enhance the flow of cooling air through the components under the engine hood. For example, the cooling fan 92, coupled to the radiator 80, may be operated to assist the flow of cooling air through the radiator 80. The cooling fan 92 may draw a flow of cooling air into the compartment 103 under the engine hood through an opening in the front of the vehicle 102, such as a radiator grille closure system 112.Such a cooling airflow can then be used by the radiator 80 and other components under the engine hood (e.g., fuel system components, batteries, etc.) to keep the engine and / or transmission cool. Furthermore, the airflow can be used to dissipate heat from the vehicle's air conditioning system. Even further, the airflow can be used to improve the performance of a turbocharged / supercharged engine equipped with intercoolers that reduce the temperature of the air entering the intake manifold / engine. In one example, the radiator grille closure system 112 can be configured with multiple air slots (or cooling fins, blades, or closures), with a controller able to adjust the position of the air slots to direct the airflow through the radiator grille closure system.

[0015] The cooling fan 92 can be coupled to the power unit 10 via a three-phase generator 72 and a system battery 74, and driven by the power unit 10. The cooling fan 92 can also be mechanically coupled to the power unit 10 via an optional coupling (not shown). During power unit operation, the torque generated by the power unit can be transmitted along a drive shaft (not shown) to the three-phase generator 72. The generated torque can be used by the three-phase generator 72 to produce electrical power, which can be stored in an electrical energy storage device, such as the system battery 74. The battery 74 can then be used to operate an electric motor 94 of the cooling fan.

[0016] The vehicle system 100 can further include a transmission 40 for transmitting the power generated in the engine 10 to the vehicle wheels 106. The transmission 40, which contains various gears and clutches, can be configured to reduce the high speed of the engine to a lower speed of the wheel, while increasing the torque in the process. To enable temperature control of the various transmission components, the cooling system 101 can also be connected to a transmission cooling system 45. The transmission cooling system 45 includes a transmission oil cooler 125 (or an oil-to-water transmission heat exchanger) located within the transmission 40 or as an integral part of the transmission 40, e.g., in the area of ​​the transmission pan at a location below and / or offset from the rotating elements of the transmission.The transmission oil cooler (TOC) 125 can have multiple plate or finned cooling elements for maximum heat transfer. The coolant from coolant line 84 can be connected to the transmission oil cooler 125 via line 46. In contrast, the coolant from coolant line 82 and cooler 80 can be connected to the transmission oil cooler 125 via line 48.

[0017] Fig. Figure 1 further shows a control system 14. The control system 14 can be coupled to various components of the power machine 10 via communication technology in order to execute the control routines and actions described here. The control system 14 can, for example, include an electronic digital controller 12, as shown in Fig. Figure 1 shows that the controller 12 can be a microcomputer containing a microprocessor unit, input / output ports, an electronic storage medium for executable programs and calibration values, a read / write memory, a hold memory, and a data bus. As shown, the controller 12 can receive inputs from several sensors 16, which may include user inputs and / or sensors (such as a gear position, accelerator pedal input, brake input, automatic shift lever position, vehicle speed, vehicle acceleration, vehicle position, engine speed, mass airflow through the engine, ambient temperature, intake air temperature, etc.), cooling system sensors (such as...The storage medium may contain coolant temperature, coolant level, coolant level sensor circuit board temperature, cylinder head temperature, blower speed, passenger compartment temperature, ambient humidity, thermostat output, etc., and other data. Furthermore, the controller 12 can communicate with various actuators 18, which may include engine actuators (such as fuel injectors, an electronically controlled intake air throttle plate, spark plugs, etc.), cooling system actuators (such as the various cooling system valves), and others. In some examples, the storage medium may be programmed with computer-readable data representing instructions that can be executed by the processor to perform both the procedures described below and other variants that are expected but not specifically listed.

[0018] Fig. Figure 2 shows an exemplary embodiment 200 of the cooling system according to Fig. 1 with various valves, loops and heat exchangers.

[0019] The coolant can circulate from different loops at the thermostat 38. The thermostat 38 itself is configured with a temperature sensing element 238 for estimating the temperature of the coolant circulating at the thermostat, while the thermostatic valve 240, which is commutatively coupled to the temperature sensing element, is configured to open only when the temperature is above a threshold value. For example, the thermostatic valve 240 can be a mechanically actuated valve, such as a wax plug for actuation force / displacement, which opens when the coolant sampled at the temperature sensing element (the wax) is above the threshold temperature.

[0020] The coolant can circulate along a first bypass loop 220 from the engine 10 to the thermostat 38. From there, the coolant can be pumped back to the engine by the pump 86. The coolant can also circulate along a second heating device loop 222 from the engine 10 via the heater 90 and the engine oil cooler (EOC) 225 to the thermostat 38. From there, the coolant can be pumped back to the engine by the pump 86. The coolant can also circulate from the engine 10 through the cooler 80 via a third loop 224 to the thermostat 38, depending on the state of the thermostat valve 240. Specifically, if the thermostat valve 240 is open, the coolant can circulate through the cooler 80 and then through the thermostat valve 240.The flow of coolant through the radiator allows the heat from the circulating hot coolant to be dissipated to the ambient air by the radiator fan. After passing through the thermostatic valve, the coolant can be pumped back to the engine by pump 86. The coolant can circulate along a fourth coolant loop 226 either from radiator 80 or from water outlet 204 through transmission oil cooler 125 and then to engine oil cooler 225.

[0021] The coolant can flow from the water outlet 204 and the radiator 80 to the degassing bottle 208, which can serve as a coolant reservoir within the cooling system 200. The degassing bottle 208 can be fluidically connected to the vertically oriented standpipe 210 via an upper level sensor hose 214 and a lower level sensor hose 216, as described in the Fig. 3-7 is further described. The upper level sensor hose can connect the top of the degassing bottle 208 to the top of the vertical standpipe 210 and can be configured to allow air to flow between the two. The lower level sensor hose 216 can be connected to the degassing bottle 208 via an outlet hose 216 of the degassing bottle and can be configured to allow coolant to flow between the degassing bottle 208 and the vertical standpipe 210. The vertical standpipe 210 can contain a piezoelectric coolant level sensor (PZT) 212, which is electronically connected to the controller 12.

[0022] As the fluid in the cooling system heats up, it expands, causing pressure to build up. For cooling systems with overflow bottles, the radiator cap may be the only place where this pressure can escape. The setting of the radiator cap spring determines the maximum pressure in the cooling system. When the pressure reaches, for example, 15 psi, it pushes open a valve in the radiator cap, allowing the pressurized coolant to escape from the cooling system. This coolant flows through the radiator's overflow tube into the overflow bottle. Consequently, this arrangement keeps air out of the cooling system. As the radiator cools back down, a vacuum is created in the cooling system, which opens a spring-loaded valve, drawing coolant from the bottom of the overflow bottle back into the radiator.

[0023] While overflow systems control pressure by allowing coolant to be exchanged through a valve, active degassing systems control pressure by allowing air to be exchanged through a valve. In degassing systems, the thermal expansion of the coolant causes the fluid to flow into the degassing bottle, increasing the atmospheric pressure inside. When the atmospheric pressure inside the bottle exceeds an upper threshold pressure, such as 21 psi, the pressure opens a valve, allowing the air to escape. In one example, this valve might be located in the filler cap of the container (e.g., the 304 cap of the degassing bottle). Fig. 3) If the air has been released from the system, the pressure in the degassing bottle will be below atmospheric pressure the next time the system cools back to ambient temperature. Under this condition, another valve located in the filler cap opens to allow ambient air to re-enter the degassing bottle. The degassing bottle gets its name from the fact that it separates the air entrained in the refrigerant. Some refrigerant from various locally high points in the cooling system is allowed to flow back to the degassing bottle through the vent pipes.

[0024] The cooling system 200 may also include a turbocharger 206. The coolant can circulate from the water outlet 204 through the turbocharger 206 and via a turbo outlet hose 208 to the outlet hose 219 of the degassing cylinder. The turbo outlet hose 218 can be connected to the outlet hose 219 of the degassing cylinder downstream of the connection between the lower level sensor hose 216 and the outlet hose 219 of the degassing cylinder. In this way, the high-temperature coolant and / or vapor passing through the turbo outlet hose 218 cannot affect the fluid transfer between the degassing cylinder 208 and the vertical standpipe 210.

[0025] One or more temperature sensors can be coupled to the cooling system at the hot water outlet of the engine to estimate the coolant temperature. The coolant temperature can be estimated, for example, by an engine coolant temperature sensor (ECT sensor) positioned to be in contact with the heated coolant. Alternatively, the coolant temperature can be estimated by a cylinder head temperature sensor (CHT sensor) positioned on the engine block, for example, a few millimeters of aluminum away from the flowing engine coolant in the cylinder head. The coolant temperature can also be estimated within the vertical standpipe 210, and a circuit board temperature can be estimated within the circuit board of the coolant level sensor 212, as described in relation to Fig. 7 is described further.

[0026] As detailed here, the vertical standpipe can be fluidically coupled to the coolant overflow reservoir, so that the coolant level in the reservoir equalizes with the coolant level in the vertical standpipe. Consequently, a controller can be configured to infer the coolant level in the degassing bottle based on the coolant level in the vertical standpipe. This allows for an accurate estimation of the coolant level without the problems associated with using a level sensor in the degassing bottle. Furthermore, the coolant level in the vertical standpipe can be used to adjust engine operation to reduce engine overheating resulting from low coolant levels in the degassing bottle.

[0027] Fig. Figure 3 provides a view of the positioning of the vertical standpipe with respect to the degassing cylinder and the vehicle frame. The vertical standpipe, generally indicated at 310, is attached to the frame 302 via several components within a standpipe mounting support 310, as shown with respect to the Fig. 4, Fig. 5, Fig. 6 and Fig. 7 is described in more detail. The vertical standpipe 310 can also be attached to the frame 302 via the lower standpipe mounting supports 321a and 321b. The position of the vertical standpipe 310 within the environment under the engine hood is based on several criteria, including ensuring sufficient space for routing the upper level sensor hose 314 and the lower level sensor hose 316 between the vertical standpipe 310 and the degassing bottle 308, and mounting the standpipe on a fixed and rigid support to prevent damaging vibrations. Furthermore, the distance between the standpipe and the degassing bottle is minimized to reduce the effect of vehicle acceleration and vehicle position on the difference between the fluid level of the standpipe and the fluid level of the degassing bottle.In this preferred embodiment, the standpipe is aligned with the lateral centerline of the degassing bottle, thereby minimizing the influence of lateral acceleration and lateral inclination on the difference in fluid levels between the standpipe and the degassing bottle. As in . Fig. As shown in Figure 3, the transverse direction runs into and out of the side. Furthermore, the longitudinal distance (from left to right) can be... Fig. 3) between the degassing bottle and the vertical standpipe such that the longitudinal acceleration and the uphill / downhill stops provide fluctuations in the fluid level of the vertical standpipe and thereby provide the ability to confirm the continuous sensor function.

[0028] The vertical standpipe mounting supports 320, 321 can be incorporated as part of the standpipe wall 382. Alternatively, the standpipe can be attached to the standpipe wall 382 by one or more bolts, welding, etc. The vertical standpipe 310 is mounted such that its principal axis is aligned with the force of gravity when the vehicle is at rest on a horizontal plane. The vertical standpipe 310 and the degassing cylinder 308 have a fixed relative position. The orientation of the vertical standpipe 310 is configured such that the principal axis of the vertical standpipe is parallel to the vertical axis of the degassing cylinder. That is, the vertical standpipe 310 and the degassing cylinder 308 can be configured to have a common horizontal plane on their upper surfaces.However, the underside of the vertical standpipe can be positioned lower than the bottom of the degassing bottle. This specific configuration ensures that a minimum threshold level of coolant is present in the standpipe, even when the coolant level in the degassing bottle is nearly empty. Such a configuration can be used because ultrasonic level sensors cannot measure below a minimum level. If the sensor is positioned so that its minimum level is below the outlet of the degassing bottle, any coolant in the degassing bottle will remain within the sensor's measuring range. As such, the risk of the degassing bottle running dry and causing engine overheating is reduced.In this way, a coolant level can be defined by a common horizontal plane that intersects both the degassing bottle 308 and the vertical standpipe 310 when the vehicle is at rest on a horizontal plane (as with respect to . Fig. 4 (as described further).

[0029] The vertical standpipe 310 can include a standpipe cap 312, an ultrasonic level sensor for measuring a coolant level (not shown), and a sensor housing 360. The vertical standpipe 310 is fluidically coupled to the degassing bottle 308 via the upper level sensor hose 314 and the lower level sensor hose 316. Specifically, the upper level sensor hose 314 is positioned to allow air to flow between the top of the vertical standpipe 310 and the top of the degassing bottle 308, while the lower level sensor hose 316 is positioned to allow coolant to flow between the bottom of the vertical standpipe 310 and the bottom of the degassing bottle 308.In this way, the fluid level between the vertical standpipe 310 and the degassing bottle 308 can reach an equilibrium level when the vehicle is at rest, which facilitates a comparison of a coolant level inside the vertical standpipe and a coolant level in the degassing bottle.

[0030] The degassing cylinder 308 comprises, in addition to the upper level sensor hose 314, a degassing cylinder cap 304, a degassing inlet hose 306, and a degassing outlet hose 319. The degassing cylinder 308 may comprise an upper part 311 and a lower part 313. In alternative embodiments, the degassing cylinder 308 may comprise a single part or more than two parts. The degassing cylinder 308 may be attached to any tall and rigid structure in such a way that the degassing cylinder 308 is substantially horizontal. Being substantially horizontal means being in a position in which the upper side extends along a plane that is substantially perpendicular to the direction of gravity, for example, within 5 degrees from the perpendicular along each axis of extension.As an example, the degassing cylinder 308 can be attached to an inner bumper by means of a degassing cylinder mounting bracket 309. In one example, the degassing cylinder mounting bracket 309 can be included as part of the lower section 313 of the degassing cylinder. In other examples, the degassing cylinder mounting bracket 309 can be attached to the lower section 313 of the degassing cylinder by means of a fastening mechanism. In still other examples, the degassing cylinder mounting bracket 309 can instead be attached to the upper section 311 of the degassing cylinder or be included as part of the upper section 311 of the degassing cylinder. When the degassing cylinder cap 304 is attached to the degassing cylinder 308, it can prevent the refrigerant in the refrigerant reservoir from evaporating and escaping into the atmosphere.When the degassing bottle cap 304 is removed from the degassing bottle 308, an opening in the top of the degassing bottle 308 may be exposed for adding more coolant to the system. Coolant may also be introduced into the degassing bottle 308 from other components of the cooling system via the inlet hose 306 of the degassing bottle. The inlet hose may, for example, carry coolant from the radiator to the degassing bottle. In some examples, the degassing bottle cap 304 may include a valve, such as a pressure relief valve or a spring-operated valve. When the fluid in the radiator heats up, such as due to extensive heating of the engine, the coolant expands, causing the pressure in the cooling system to increase. The pressure in the cooling system may escape through the degassing bottle filler cap 304.Specifically, the maximum pressure in the degassing cylinder can be determined by a spring-loaded valve in the degassing cylinder filling cap 304. When the pressure reaches a threshold, such as 21 psi, it opens the valve in the degassing cylinder filling cap 304, allowing the pressurized air to escape from the degassing cylinder to the environment under the engine hood. As the system cools back down, a vacuum is created, drawing air back from the environment under the engine hood through another valve in the degassing cylinder filling cap 304.

[0031] Fig. Figure 4 provides an alternative view of a section of a cooling system, further detailing the fluidic coupling of the degassing cylinder 308 and the vertical standpipe 310. A sensor 340 can be attached to the bottom of the degassing cylinder 308 to directly measure the fluid levels within the cylinder. The sensor 340 can be positioned within the sensor housing 342. The sensor 340 can be connected to the electronic control system and can be enabled to communicate with the controller 12 via the (not shown) controller area network.

[0032] The lower level sensor hose 316 is connected to the outlet hose 319 of the degassing cylinder via a T-connection 332. The T-connection 332 is oriented such that the 90-degree branch from the outlet hose 319 points downwards, so that any entrained bubbles in hose 319 tend to bypass hose 316. Furthermore, if the coolant is missing from the degassing cylinder 308 and the outlet hose 319 of the degassing cylinder, a volume of coolant can remain "trapped" in the lower level sensor hose 314 and in the vertical standpipe 310. This trapped coolant volume can be measured by the ultrasonic level sensor 362. Additionally, a connection between a turbo outlet hose (218 to Fig. 2) and the outlet hose 319 of the degassing cylinder downstream of the T-connection 332 (which is in Fig. 4 (concealed by the vertical standpipe 310). This connection can be made by a second T-connection 334, oriented such that the 90-degree branch from the outlet hose 319 of the degassing bottle points upwards and is antiparallel to the branch of the T-connection 332. In this way, the hot and / or vaporized coolant generated by the backflow from the turbo outlet hose 218 (where the backflow changes as a function of the engine speed) cannot affect the coolant level difference between the degassing bottle 308 and the vertical standpipe 310. The lower level sensor hose 316 can be set at a level below a blanking distance associated with the ultrasonic level sensor 362 (as described below with respect to the Fig. 7 and Fig. (as discussed further in section 11) and also coupled to the side of the vertical standpipe 310.

[0033] The vertical standpipe 310 is positioned such that its base is below the base of the degassing cylinder 308 and below the T-connection 332. If the coolant level in the degassing cylinder 308 approaches or falls below the base of the cylinder, the corresponding local coolant level in the standpipe 310 can remain at a specified level substantially above the ultrasonic level sensor (ULS) 362. The specified level can be based on the level of a horizontal plane extending from the top of the T-connection 332. If the local coolant level in the standpipe is estimated to be zero, deterioration of the coolant system, such as...a separate hose may be specified, whereas if it is estimated that the local coolant level in the standpipe is within a threshold distance of the specified level, an empty degassing bottle may be specified.

[0034] As in Fig. As shown in Figure 4, the vertical standpipe 310 is attached to the frame 302 such that the upper part of the vertical standpipe occupies the same horizontal plane as the upper part of the degassing bottle 308. The vertical standpipe 310 has a greater vertical extent than the degassing bottle 308, so that the bottom of the vertical standpipe 310 is located below the bottom of the degassing bottle 308. When the degassing bottle 308 is empty, a level of coolant can remain in the vertical standpipe 310, providing a medium interface from which the ultrasonic pulses from the ULS 362 can be reflected. At fluid equilibrium, the local coolant level in the vertical standpipe 310, corresponding to an empty degassing bottle, can be defined by a horizontal plane extending the upper part of the T-connection 332, as shown by the line 333 of the coolant level in Figure 4. Fig. Figure 4 is shown. In this way, a specified level measurement in the vertical standpipe 310 can be associated with an empty coolant volume level in the degassing bottle 308, which makes it possible to distinguish a measurement of an empty coolant volume level from a condition, such as a disconnected hose, which may cause an empty local coolant level in the vertical standpipe 310.

[0035] The vertical standpipe 310 can be equipped with a standpipe cover 312. The standpipe cover 312 can be configured to fit into the upper part of the vertical standpipe 310 such that the main axis of the standpipe cover 312 is parallel to the main axis of the vertical standpipe 312. The standpipe cover 312 can have a smooth surface 380 that can facilitate the reflection of sound waves, such as those emitted by the ultrasonic level sensor 362. As an example, the standpipe cover 312 can be manufactured using a friction welding technique. The vertical standpipe 310 can be a cylindrical shell with a sufficiently small horizontal cross-section to act as a waveguide for the ultrasonic sound waves. As a non-limiting example, the horizontal cross-section of the vertical standpipe 310 can be approximately 17.25 millimeters in diameter and slightly larger than the scanning element of the ultrasonic level sensor.The wall 382 of the vertical standpipe can be made of a smooth, rigid plastic, e.g. a PA66 material with 30% glass filling.

[0036] The ultrasonic level sensor (ULS) 362 can be a piezoelectric transducer element capable of both transmitting and receiving ultrasonic pulse signals. The ULS 362 can be fixed within the sensor housing 360 at the base of the vertical standpipe 310 and configured to emit sound pulses upwards through the cavity of the pipe. The ULS 362 can be electronically connected to a ULS circuit board 364. The ULS circuit board 364 can physically extend over the ULS 362 and can be connected to a force machine controller (e.g., 12 according to the Fig. 1-2) are electronically connected. In a non-restrictive example, the sensor 340 can also be an ultrasonic level sensor configured to perform direct estimations of the coolant level in the degassing bottle 308. The sensor housing 360 can be sealed to an upper wall 382 of the standpipe with an O-ring and held in place by a metal spring clamp 336 to allow for quick assembly of the two halves of the standpipe wall. The sensor housing 360 can be made of a material with a coefficient of thermal expansion closer to that of the upper standpipe 382, ​​e.g., PPS GF30. The lower cover 368 of the standpipe can be attached to the bottom of the sensor housing 360 and protect any sensor components from the environment.The cavity surrounding the circuit board 364 and the ULS 362 can be filled with a flexible potting compound to further improve isolation from the environment.

[0037] Furthermore, in Fig. Figure 5 provides a bird's-eye view showing the relative positioning of the degassing bottle 308, the vertical standpipe 310, and the frame 302. The degassing bottle mounting support, shown here attached to the lower part 313 of the degassing bottle, may include a multi-toothed hole to allow sufficient compliance for assembly while maintaining an interference fit after assembly. The upper level sensor tube 314 is shown to run horizontally between the upper part 314 of the degassing bottle and the top of the vertical standpipe 310.

[0038] As shown, the vertical upright 310 can include an upper mounting support 320 extending horizontally above the frame 302 and one or more (not shown) lower mounting supports extending horizontally below the frame 302, while the vertical upright is attached adjacent to a vertical end face of the frame 302. A fastening element 322 for attaching the upright extends vertically from inside the upper mounting support 320 and through the frame 302, restricting the movement of the vertical upright 310. The fastening element 322 for attaching the upright can extend through a metal load limiter 324 above the frame 302, thereby preventing a common clamping load reduction that can occur over time due to creep in the upper mounting support 320.

[0039] A spring-loaded retaining clip 336, located on the upper section of the vertical standpipe 310, can be configured to provide robust retention and rapid assembly of the two halves of the vertical standpipe 310. The lower cover 368 of the standpipe is shown attached to the bottom of the vertical standpipe 310, shielding the ULS 362 and the ULS circuit board 364 from the environment. As shown here, the lower level sensor tube 316 is coupled to the vertical standpipe 310 below the spring-loaded retaining clip 336 and above the lower cover 368 of the standpipe.

[0040] In Fig. Figure 6 shows in more detail the attachment of the vertical upright 310 to the frame 302. The frame 302 contains several cruciform support structures 303 between a top and a bottom of the frame. A fastening wedge 326 can be inserted within a cavity of one of the cruciform support structures 303 to assist in attaching the vertical upright 310 to the frame 302. The fastening wedge 326 can be designed to fit into an inner grid of the cruciform support structure. If the inner grid has, for example, an essentially triangular shape, the fastening wedge can also be configured to have a matching triangular shape, thus achieving a tight fit. The top of the fastening wedge 326 can be in direct contact with the bottom of a top of the frame 302.The fastening element 322 for attaching the upright can extend vertically from above the frame 302 through the metal load limiter 324, through the upright mounting support 320, through a cavity in the frame 302, and through a cavity in the mounting wedge 326. The fastening element 322 for attaching the upright can be coupled to the mounting wedge 368 via a J-clamp 328. In this way, by coupling the upright mounting support 320 to the mounting wedge 326, which is housed within a cross-shaped support structure 303, the stability of the position of the vertical upright 310 relative to the frame 302 can be improved.

[0041] As shown, the vertical standpipe 310 can extend substantially below the section of the frame 302 to which it is attached. The sensor housing 360 can extend horizontally from the vertical standpipe 310 below the frame 302. The sensor housing 360 can include a cavity to accommodate the lower level sensor tube 316 and can provide an electrical connection to the controller 12.

[0042] Fig. Figure 7 provides a cross-sectional view of the vertical standpipe 310, the configuration of the ULS 362 and the sensor housing 360, and the configuration of the upper mounting structure, which includes the mounting support 320 and the fastening element 322. The vertical standpipe 310 is configured to be coupled to the upper level sensor tube 314 adjacent to the standpipe cover 312 along the wall 382 of the standpipe. The vertical standpipe 310 is further configured to be coupled to the lower level sensor tube 316 just above the ULS circuit board 364.

[0043] The mounting support 320 can be incorporated as part of the wall 382 of the vertical standpipe, as shown. The fastening element 322 can be oriented perpendicular to the underside of the mounting support 320 and to the top of the mounting wedge 326. The fastening element 322 can be a suitable fastening mechanism, such as a bolt or screw.

[0044] Moving to the lower section of the vertical standpipe 310, it is shown that the ULS circuit board 364 is connected to the ULS 362, the coolant temperature sensor 367 (which is located in Fig. (as shown in Figure 4) and is electrically connected to the circuit board temperature sensor 369. The coolant temperature sensor 367 can be positioned above the ULS circuit board 364, while the ULS circuit board temperature sensor 369 can be positioned below the ULS circuit board 364. The temperature sensors 367 and 369 can be configured to periodically or continuously estimate the temperatures of the coolant within the vertical standpipe 310 and the ULS circuit board 364, respectively. In one example, the ULS circuit board temperature sensor 369 can be a surface-mounted thermistor attached to the surface of the ULS circuit board 364.

[0045] The ultrasonic level sensor 362 is configured to periodically generate sound waves to develop usable sensor data. In some embodiments, the ULS 362 can be configured to generate a set of multiple ultrasonic pulses (e.g., five pulses) spaced sufficiently apart to allow enough time for the pulses to travel the length of the standpipe and return to the sensor (based on the length and speed of sound in the fluid) before another pulse is emitted (e.g., 5-8 milliseconds between pulses), and to periodically generate a set of pulses at each total interval (e.g., every 100 milliseconds). The ULS 362 can continuously generate these sound signals during conditions when the ignition state is in a running mode of the power engine. The ULS 362 is a transmit / receive device and is configured accordingly to receive sound waves.When the ULS 362 is located in the vertical standpipe 310 and a fluid is present in the standpipe, the pulses generated by the ULS 362 are reflected by a fluid-air interface or by a cover 312 of the vertical standpipe, traveling back to the ULS 362. If the energy of the returning pulse is above a lower threshold energy, the returning pulse transfers a portion of its energy and can be received by the ULS 362. The term "first-order echo" can also be used here to refer to this returning pulse. The term "echo" can refer to this returning pulse unless otherwise specified. In some sensors, the returning pulses are reflected at the bottom of the fluid cavity, traveling to the fluid-air interface and being reflected a second time. These waves then travel back to the ULS 362.This return of the second harmonic, which is also referred to here as a second-order echo, can also be detected and can be used for signal verification and more complex operation.

[0046] The circuit board 364 of the ultrasonic level sensor can contain a memory with instructions to adjust the power level supplied to the ULS 364 based on the energy associated with the ultrasonic pulse signals received by the ULS 362. For example, regarding Fig. As described in more detail in section 10, if the energy associated with a set of ultrasonic pulse signals is greater than an upper threshold, or if the number of second-order echoes associated with a set of pulses is greater than a threshold number, the ULS circuit board 364 (e.g., by the force machine controller 12) Fig. 1) be controlled to reduce the power supplied to the ULS 362 for emitting ultrasonic pulses. As another example, if the energy associated with a set of ultrasonic pulse signals is less than a lower threshold, the ULS circuit board 364 (e.g., by the force machine controller 12) can be controlled to reduce the power supplied to the ULS 362 for emitting ultrasonic pulses. Fig. 1) The power supplied to the ULS 362 for emitting ultrasonic pulses can be increased. Pulse energy that is less than a lower threshold may result in no ultrasonic pulse being detected when a pulse would be expected. The ULS circuit board 364 is configured to measure time and may contain programs in memory configured to capture the timestamps of the ultrasonic pulses received by the ULS 362. The ULS circuit board 364 is further configured to estimate the temperatures of the assembly and the fluid via the temperature sensors 367 and 369, respectively (e.g., via measurements of the thermistor voltage from sensors 367 and 369). In this way, the ULS circuit board 364 can generate improved estimates of a standpipe coolant level based on the ultrasonic pulse times and the temperature estimates.The ULS circuit board 364 can be configured to send the data to the controller 12 via a CAN bus, including the temperature estimates from the sensors 367 and 369, the ultrasonic pulse timestamps, the ultrasonic pulse energy levels, and the sensor-processed estimates of the standpipe coolant level (as per . Fig. 11 further described), but not limited to that.

[0047] The ULS 362 can also be configured to send information via a controller area network to a power machine controller (such as the controller 12). Fig. 1) to broadcast as specified. In one example, the ULS 362 can be a one-way or broadcast-only device in the CAN.

[0048] Fig. Figure 8 shows a detailed view of the standpipe cover 312. The standpipe cover 312 can be manufactured by friction welding. The standpipe cover 312 can be cylindrical and include a circumferential groove 384 configured to receive and rest on the top of the wall 382 of the vertical standpipe. The surface 380 of the standpipe cover can be located within the area enclosed circumferentially by the groove 384. The surface 380 of the standpipe cover can be designed to be smooth, flat, and parallel to the emission surface of the ULS 362. In this way, the surface 380 of the standpipe cover can efficiently reflect the sound waves emitted by the ULS at the bottom of the standpipe. By improving the efficiency of sound reflection, the accuracy of the fluid level estimates in the vertical standpipe is increased when the standpipe is full of fluid.If the lid surface 380 is rough or angled relative to the ULS 362, the reflected sound can be scattered away from the ULS 362, making the standpipe appear empty. This, in turn, improves the reliability of estimating the coolant level in the degassing bottle.

[0049] Fig. Section 9 provides a high-level routine 900 for determining a coolant volume level in a degassing bottle based on a reading from the level sensor in a fluidically coupled vertical standpipe, such as the degassing bottle 308 and the vertical standpipe 310. The routine further describes the adjustment of the engine parameters based on the coolant volume level. Routine 900 can be executed continuously during engine operation to ensure a sufficient coolant level in the cooling system to prevent overheating of any engine components. Each iteration of routine 900 can be referred to here as a measurement period.The routine includes estimating a coolant level in the vertical standpipe based on data from the ultrasonic level sensor, adjusting the coolant level estimate in the vertical standpipe based on sloshing parameters such as vehicle speed, vehicle position, and previous coolant levels to determine the current coolant level in the degassing bottle, setting a long-term coolant volume level based on the estimate of the current level in the degassing bottle, and adjusting the engine operating parameters based on the long-term coolant volume level.

[0050] Routine 900 begins at 902, where an ultrasonic level sensor can periodically emit a set of ultrasonic pulses upwards from the bottom of the vertical standpipe. As described above, a ULS can, for example, emit a set of 5 consecutive ultrasonic pulses with a specified energy, each pulse spaced 5-8 milliseconds apart. The energy of the emitted pulses can be determined based on several factors, including feedback from the energy of previously received pulses. Specifically, the energy of the pulses can be increased if the preceding returning pulses were below a threshold energy level or were not detected, while it can be decreased if more than a threshold number of second- and / or third-order harmonic echoes were detected.The time interval between each pulse set can be determined based on the expected values ​​of the fluid's speed of sound and the total length of the standpipe to be measured, such that the interval is at least longer than the period of the first harmonic of the pipe / fluid. The ULS can, for example, emit a set of pulses every 100 milliseconds.

[0051] Once an ultrasonic pulse has been emitted by the ULS, it can travel upwards through the coolant in the standpipe until it reaches a medium interface, such as a coolant-air interface, or an air-solid interface if the standpipe does not contain coolant. Some of the energy associated with the ultrasonic pulse may be reflected at the interface, generating an echo pulse, while the remainder of the energy associated with the ultrasonic pulse may be transmitted or refracted through the interface or dissipated in some other way. The echo pulse may travel back to the ultrasonic level sensor and may be detected by the ultrasonic sensor at 904. This echo can be referred to as a first-order echo.In some examples, an echo pulse may be at or below a lower threshold energy and, as such, may not be detectable by the sensor. In other examples, the echo received by the ultrasonic level sensor may be a second echo associated with an emitted pulse. Each detected echo can be assigned a timestamp, as described in more detail below.

[0052] When multiple successive echoes with sufficient energy are returned, the assigned timestamps for the primary, secondary, and tertiary echoes can be compared to each other and to multiples of the primary echo. These echoes are correlated with the expected harmonic response. These timestamps are provided with sufficient temporal resolution for accurate signal analysis and indicate the time elapsed between the emission and reception of that echo. This timestamp can also be referred to as an echo time. In some examples, a timestamp may be assigned only to pulses with an energy at or above a lower threshold energy.If a single ULS is configured to both transmit and receive signals within the standpipe, the sensor may be configured to ignore received pulses for a threshold duration after the emitted excitation has ceased. This threshold duration can be referred to here as a "blanking period," which correlates with a potential reflection that may occur at the bottom of the fluid interface and could indicate a false low fluid level. The blanking period can be determined based on various factors, such as the materials used in the sensor housing, the coupling materials that facilitate transmission from the transducer to the housing, and other geometric features present in the standpipe. The internal computer or processor of the ULS circuit board may also classify the echoes as first-order or higher-order echoes, such as...Second-order echoes, they are called.

[0053] At 906, the ULS's internal computer can determine an echo time for each received pulse. Based on these echo times, the ULS computer can also determine an internal estimate of the local coolant level in the standpipe. This internal coolant level estimate can be based on an estimated speed of sound in the coolant, including a temperature compensation factor and an echo time. A coolant level can be estimated for each received first-order echo within a measurement period. An average of the coolant levels within a given measurement period can be determined to arrive at a final sensor-processed local coolant level in the vertical standpipe. A comparison is then performed between these signals to ensure that the signal represents a true detection of the fluid level.During conditions where excessive fluid turbulence or fluid-air motion within the pulse could be mistaken for less accurate measurements, a more complex statistical condition than an arithmetic mean may be necessary to analyze the first-order echo timestamps. Consequently, determining an average may involve calculating one or more mean values, modes, medians, weighted averages, other statistical functions, and standard deviations, and then processing the coolant levels using an appropriate mean or median based on the outliers in the data samples. For example, if the primary echo times within the set of pulses are all within 1 millisecond of each other, a high-quality signal can be reported.However, if one primary echo time is significantly different from the other, a lower confidence level can be specified.

[0054] At 908, the amount of power supplied to the ULS for pulse emission can be set based on the energies and / or the number of pulses of the first and second echo times for the current measurement period. For example, a routine 1000 (in Fig. 10) to adjust the power supply. Adjusting the power supplied to the ULS for pulse emission can involve selectively increasing the power when a first threshold number of received pulses is below a lower threshold energy, and selectively decreasing the power when a second threshold number of higher-order echoes is received during the measurement period. The threshold number of received pulses can be based on the presence of any primary echo data (the threshold number can, for example, be the pulse set size), while the threshold number of higher-order echoes can be based on the available second-order echo times. Adjusting the power supplied to the ULS is described below with respect to Fig. 10 further described.

[0055] The ULS can transmit information associated with the emitted and received pulses of the current measurement period to the power machine controller (such as controller 12) at port 910. For example, the ULS can transmit the number of received echoes above the lower threshold energy, a sensor-processed estimate of the local coolant level, the timestamps for the first- and second-order echoes of each emitted pulse in the measurement period, and estimates of the temperatures of the sensor circuit and the standpipe coolant. The temperature estimates of the ULS circuit board and the standpipe coolant can be determined via sensors 367 and 369, respectively. Based on this information, the power machine controller can then determine a coolant level in the vertical pipe. This coolant level in the vertical pipe can be referred to as a local coolant level or a local level.Determining a local coolant level can involve applying the sensor-processed estimate of the local coolant level, or alternatively, calculating a level based on the echo times, blanking distance, and the physical extent of the standpipe. Determining a local coolant level is described with respect to... Fig. 11 described in more detail.

[0056] The coolant level in the standpipe may not directly correspond to the coolant level in the degassing bottle, the latter also referred to here as the coolant volume level or volume level. For example, if the vehicle is accelerating, decelerating, or stationary, the local coolant level may differ from the coolant volume level due to sloshing. To account for this difference between the volume level and the local level due to sloshing, the engine controller can calculate a compensation term. This compensation term can be used to adjust the estimate of the local coolant level to an estimate of the coolant volume level at 914, for example, via routine 1400. Fig. 14. The compensation term can be based on the vehicle's motion parameters, e.g., on one or more of the longitudinal position and longitudinal acceleration, the lateral position and lateral acceleration. Applying compensation to the estimate of the local coolant level to adjust for sloshing is described in relation to... Fig. 14 described in more detail.

[0057] After a set estimate of the local coolant level for the measurement period has been determined in step 914, routine 900 proceeds to step 916, where the coolant volume level estimate can be set based on the set estimate of the local coolant level. Setting the coolant volume level estimate can involve filtering the set estimate of the local coolant level into the overall coolant volume level estimate. The process of setting the coolant volume level estimate is described below with regard to... Fig. 14 and Fig. 16. The coolant volume level estimation cannot be set during measurement periods in which a local coolant level estimate is not being determined. A coolant volume level estimate can correspond to one or more coolant volume states, where the coolant volume states are defined by one or more level thresholds.

[0058] Routine 900 then proceeds to 918, where the vehicle's coolant condition can be set based on an estimated coolant volume level. The vehicle can have a fixed number of possible coolant conditions, such as EMPTY, LOW, OK, FAILURED, and UNKNOWN / DECREASE. Coolant conditions can directly correspond to a coolant volume level or indicate deterioration of hardware components, such as an ultrasonic level sensor. In some cases, setting the coolant condition can only occur if a coolant level indicating a new coolant condition has persisted for a specified threshold duration.

[0059] Based on the coolant condition, the engine's operating parameters can be set at 920. For example, if the coolant level remains below a lower threshold for a period exceeding a certain duration, and the vehicle's operating parameters indicate that an accurate coolant level can be detected, a low coolant condition can be assumed. This can lead to limiting operations, where engine loads can be restricted to remain below an upper threshold to ensure that the engine components maintain their intended operation. In another example, if the coolant condition is LOW, the controller can display a message to the engine operator indicating a low coolant level. Setting the coolant condition is done with respect to Fig. 18 is described in more detail. In some cases, a system diagnosis can be performed at 922 based on the coolant condition; for example, sensor deterioration can be determined based on the coolant condition and changes in the coolant condition during vehicle operation. Routine 900 then ends.

[0060] Fig. Section 10 presents a routine 1000 for adjusting the power supplied to the ultrasonic level sensor for pulse emission based on feedback from the energy of the received pulses. The power supplied to the ultrasonic level sensor for pulse emission can also be referred to here as the transmit power. Routine 1000 can be executed during each measurement period after the set of pulses has been received and can increase the energy efficiency of the ultrasonic level sensor.

[0061] Routine 1000 begins at 1002, where the number of first-order echoes within the set of measurements with an energy value above a lower threshold is determined and compared to a threshold number. The lower energy threshold can be determined based on a fixed minimum value. This minimum threshold number can be determined based on providing sufficient function under most steady-state operating conditions. For example, if 5 pulses were emitted during the measurement period, the threshold number could be 4 out of 5 pulses with an energy value above the lower threshold. If the number of sufficiently energetic echoes is higher than a threshold value, it can be determined that the sensor's energy output is sufficiently high. Furthermore, it can be determined that further optimization of the energy output may be possible.If the energy output is sufficiently high, the sensor's energy output can be reduced without a significant decrease in the number of sufficiently energetic echoes. By reducing the energy output without affecting the echo efficiency, the benefits of reduced power can be achieved. Furthermore, when operating at high pulse emission energies, unexpected additional pulses due to inappropriately reflected energy can be detected, leading to erroneous data being supplied to the measurement system. Consequently, it is advantageous to provide reduced ultrasonic energy whenever conditions permit.

[0062] In one example, in response to a sufficiently small number of valid first harmonic echoes being received (e.g., 0 or 1), the energy output level may be increased to attempt to obtain sufficient energy quickly enough to recover adequate first / second-order returns (e.g., an increase of 10%–20%). In another example, if all first-order harmonics are present and more than a large number of valid second harmonics are returned (e.g., more than 4 or 5 second harmonics), the amount of pulse energy transferred is reduced by a small decrement (e.g., a 1% reduction). In other examples, certain conditions may specify maintaining the current transmitted energy level if all transmitted pulses provide clear first and second echo times.

[0063] If the number of echoes with an energy value above the lower threshold is at or above the threshold, routine 1000 continues to 1004, where the energy supplied to the ULS for emitting pulses can be decreased. Conversely, if the number of echoes with an energy value above the lower threshold is below the threshold, routine 1000 continues to 1006, where the energy supplied to the ULS for emitting pulses can be increased. Here, based on the number of echoes with sufficient energy below the threshold, it can be determined that the sensor's energy output is insufficient. Furthermore, it can be determined that further optimization of the energy output is necessary. Accordingly, the ULS's energy output is increased to improve the number of echoes with sufficient energy.

[0064] The reduction of transmit power at 1004 can, under a first set of conditions, involve reducing the transmit power at a first rate, and under a second set of conditions, involve reducing the transmit power at a second rate, where the second rate is slower than the first. The first set of conditions might, for example, involve receiving a threshold number of first-order echoes above the lower energy threshold, while also receiving a number of higher-order pulses above an upper threshold. In this example, the transmit power can be reduced at a slow initial rate, intended to ensure continuity of the returning signals and exhibiting a controlled reduction in power. An excessive reduction rate can lead to dithering of sufficient and insufficient data in alternating cycles.This dithering behavior can then be misinterpreted as a loss of an accurate signal function, leading to redundant vehicle response conditions. The second set of conditions can include any first-order echo within the measurement period that is above the lower threshold energy and a number of higher-order pulses below the upper threshold. In this example, the transmit energy can be reduced at a second, slow rate, where the second rate is slower than the first. In another example, the first set of conditions can include the transmit energy being at its physically maximum level and the number of first-order echoes above the lower threshold energy being above the threshold.In comparison, the second set of conditions can include that the transmitted energy is at the physically maximum level and that the number of first-order echoes is below the threshold energy and below the threshold number.

[0065] Increasing the transmit power at 1006 can, under a first set of conditions, involve increasing the transmit power at a first rate, and under a second set of conditions, involve increasing the transmit power at a second rate, where the second rate is slower than the first. In some examples, under a third set of conditions, the transmit power can jump to the physically maximum level and be maintained at the physically maximum level until these conditions are no longer detected. The first set of conditions might, for example, include the number of first-order echoes with an energy value above the lower energy threshold that is below a lower threshold but not zero.In this example, the transmitted energy can be increased at a faster rate, determined based on the number of return valid first-order pulses below a threshold (the threshold might be, for example, 3 pulses). The second set of conditions might include a small number of return second-order harmonic pulses (less than 3), in which case the transmitted energy can be increased at a lower rate, determined based on the balance between return valid first- and second-harmonic pulses. The third set of conditions might include the number of first-order echoes with an energy level above the lower energy threshold, which is zero. In this example, the transmitted energy can be increased up to a maximum level.In some examples, if either the first or second set of conditions is detected, but the transmit power is at an upper threshold below the maximum level, the transmit power can be maintained and not increased. In another example, the transmit power can be maintained if either the first or second set of conditions is detected, but the transmit power is above the upper threshold and below the maximum level.

[0066] Fig. Section 11 provides an exemplary routine 1100, running from the beginning of 1101 to the end of 1144, for estimating the local coolant level in the standpipe based on information from the ultrasonic level sensor and the operating conditions of the engine, and for adjusting this estimate with a compensation term. During a first set of conditions, an estimate of the local coolant level can be calculated based on a sensor-processed level estimate. During a second set of conditions, the controller can calculate a level estimate based on the timestamps of the first-order echoes and / or the estimates of the coolant and ULS switching temperatures and / or an estimated coolant mixture and / or the measurements of the vehicle acceleration and position and / or the physical parameters of the standpipe. Routine 1100 can be executed during each measurement period.

[0067] At 1102, in addition to receiving the sensor-processed estimate 1108 of the coolant level, the controller receives the unprocessed data from the ultrasonic level sensor, including a number of echoes above the lower threshold energy at 1104, the echo timestamp 1106 for both first-order and higher-order echoes, and the estimates 1110 of the coolant temperature and the ULS circuit board temperature, but not limited to these. At 1112, the power machine can determine whether the power machine conditions are quiet, and if so, at 1114 it can apply the sensor-processed estimate 1108 of the coolant level as the unprocessed fluid level in the standpipe. Determining whether the power machine conditions are quiet may include determining whether the vehicle's dynamic acceleration, the vehicle's gradient / pitch, and / or the power machine speed are changing by more than threshold amounts.These parameters can be determined by a powertrain / engine control module based on information from the vehicle's accelerometers (e.g., from the roll stability or airbag module) as well as the operating parameters of the engine.

[0068] If at 1112 it is not determined that the engine conditions are quiet, the controller can proceed to calculate the local coolant level based on the echo times (1106) and temperatures (1110). At 1116, the controller checks the number of received first-order echoes that are at or above a threshold energy level. In some cases, the energy threshold may be the energy level at which a signal can be distinguished from noise. If the number of first-order echoes is at or above the energy threshold, and above a threshold number of echoes, routine 1100 to 1124 proceeds to calculate a coolant level based on these first-order echo times.The threshold number of echoes can be determined based on data collected for a basic fraction of the valid first harmonic echoes observed under steady-state idle conditions on flat ground. For example, if the measurement period includes 5 emitted pulses, the threshold could be 4.

[0069] In some examples, a first-order echo may have been incorrectly identified as a higher-order echo by the ULS board's internal processor. Accordingly, at 1118, the controller can check the timestamps of the higher-order echoes and determine whether one or more first-order echoes have been incorrectly identified as higher-order by the sensor. Determining whether a first-order echo has been incorrectly identified can be based on comparing the return timestamps of the reported first-order echoes with the calculated second- or third-order times that could occur (calculated based on the speed of sound and 4 standpipe lengths (second order) or 6 standpipe lengths (third order)). If no first-order echoes have been incorrectly identified, then the number of first-order echoes is still below the threshold.In this case, the controller may flag an invalid measurement for the measurement period at 1128 because there are not enough data points to perform a more reliable estimate of the coolant level in the standpipe. Flagging an invalid measurement period also entails not updating the coolant volume level at 1130 based on the data from the current measurement period, and at 1132 using the volume level data from the latest valid measurement period.

[0070] If, at 1118, it is determined that one or more first-order echoes have been incorrectly identified as higher-order echoes, these echoes can be reassigned as first-order echoes at 1120. The controller can then check again whether the number of first-order echoes is at or above the threshold value of the energy above the threshold number of echoes. If the number is still below the threshold, routine 1100 can proceed to 1128, 1130, and 1132, as described above. If the number is at or above the threshold, routine 1100 proceeds to 1124, where an estimate of the local coolant level can be determined, for example, via routine 1200. Fig. 12.

[0071] In Fig. Section 12, specifically routine 1200, provides an example routine for calculating an estimate of the local coolant level based on echo times and a number of temperature estimates. The calculation assumes that an ultrasonic pulse travels from the sensor to a coolant-air interface and back to the ultrasonic level sensor within the time period specified by its respective timestamp. An estimate of the distance traveled by the ultrasonic pulse is calculated based on the echo time and an estimate of the speed of sound in the coolant.

[0072] Routine 1200 begins at 1202, where the unprocessed first-order echo times and coolant temperatures are received by the controller. At 1204, the coolant mixture composition can be estimated based on a comparison of an estimated speed of sound (estimated based on an average local standpipe level on flat ground) and a currently measured speed of sound. An estimate for the speed of sound in the coolant can then be determined at 1206 based on both the estimated temperatures of the coolant and the ULS circuit, as well as the estimated coolant mixture. With an estimated speed of sound and a timestamp, the distance traveled for each pulse can be calculated at 1208 based on the following formula: Distance=0.5*v_sound*t_0, where v_sound is the estimated speed of sound, t_0 is the first-order echo time, and the product of these two is multiplied by one and a half to account for the fact that the pulse must travel twice the length of the coolant level to return to the sensor. A distance can be estimated for each first-order echo in the set that lies above the lower threshold energy.

[0073] Back to Fig. 11. At 1126, the standpipe coolant level estimates of routine 1200 can be compared with the physical range of the standpipe. The controller's memory can, for example, contain an upper threshold for a maximum coolant level based on the distance between the ULS sensor and the top of the vertical sensor, and a lower threshold for a minimum coolant level based on the distance between the ULS sensor and the lower level sensor tube (316 in). Fig. 3) included. In other examples, the lower threshold may be based on the sensor's blanking distance. The standpipe's physical range may then be any level between the upper and lower physical thresholds. If the local level estimates are not within the standpipe's physical range, routine 1100 continues to 1128. In some examples, presence within the standpipe's physical range may include presence within a threshold range below the lower physical threshold or within a threshold range above the upper physical threshold. In these examples, the threshold ranges may be determined based on worst-case expected part tolerances and further based on the upper and lower physical thresholds themselves.

[0074] However, if the estimated standpipe levels are within the standpipe's physical range, routine 1100 continues to 1134, where a decision is made based on whether the estimated standpipe levels are within the standpipe range or within the threshold tolerances outside the unprocessed standpipe. If the unprocessed standpipe level is outside the standpipe range and within the threshold tolerances, the unprocessed standpipe level is clipped at 1136 to ensure it remains within the physical range. If the unprocessed standpipe level is within the physical range at 1134, clipping may not be necessary, and routine 1100 may continue to 1138.

[0075] At 1138, an average of the calculated and clipped level estimates can be determined. Determining an average may involve one or more steps of checking a mean, median, and standard deviation, and then processing the coolant levels using an appropriate mean or median based on the outliers in the data samples. For example, if one or more of the samples are outside the physical range, determining an average may include only the points that were originally measured within the range. This average can be applied as the unprocessed estimate of the local coolant level or the unprocessed estimate of the standpipe coolant level for the measurement period. This average can then be applied at 1140 as the unprocessed estimate of the standpipe coolant level.At 1142, a separate routine can be executed to estimate the coolant volume level based on the unprocessed estimate of the standpipe coolant level and other factors, such as vehicle acceleration and position. The routine 1400 after... Fig. Procedure 14 can be performed, for example, to estimate a coolant volume level. This process is described with respect to the Fig. 13-16 described in more detail.

[0076] The Fig. Figures 13A-13C provide illustrations of a coolant reservoir (the degassing bottle 1302) fluidically coupled to a vertical standpipe 1304 and oriented at three different angles with respect to a horizontal plane. The degassing bottle 1302 is shown with the degassing bottle cap 1328. An upper fluidic connection is established between the degassing bottle 1302 and the vertical standpipe 1304 via an upper level sensor tube 1326, allowing air transfer between the top of the degassing bottle 1302 and the top of the vertical standpipe 1304. When the degassing bottle 1302 and the vertical standpipe 1304 are horizontal, the upper level sensor tube 1326 can extend horizontally between the two vessels, as shown in Figure 13A-13C. Fig. Figure 13A illustrates this. A lower fluidic connection is established via the lower level sensor hose 1318 between the degassing bottle 1302 and the vertical standpipe 1304, enabling the transfer of coolant 1306 between the degassing bottle 1302 and the vertical standpipe 1304. The lower level sensor hose is coupled to the outlet hose 1316 of the degassing bottle via a T-connection 1320, which is oriented such that the lower level sensor hose 1318 diverges from the outlet hose 1316 in a downward direction. The lower level sensor hose 1318 is connected to the outlet 1316 of the degassing bottle below the bottom of the degassing bottle 1302 and upstream of the turbo outlet 1322. The vertical standpipe 1304 can contain a ULS 1308 for estimating a local coolant level. The ULS 1308 can be connected to a controller area network (not shown).

[0077] By establishing a fluidic connection between a larger vessel, such as the degassing bottle 1302, and a smaller, narrower vessel, such as the vertical standpipe 1304, fluid transfer between the two vessels has a greater effect on the coolant level of the smaller vessel than on that of the larger vessel. Under certain conditions, the local coolant level 1314 and the coolant volume level 1312 may be the same or at least within a lower threshold of each other, as in Fig. Figure 13A illustrates the conditions under which the local coolant level 1314 and the coolant volume level 1312 are within a lower threshold of each other. These conditions may include when the vehicle is not accelerating and when the vehicle is in a level position. Under other conditions, fluid transfer between the degassing bottle 1302 and the vertical standpipe 1304 may cause the local coolant level 1314 to be higher than the coolant volume level 1312 by at least a threshold amount. Exemplary conditions that may cause such fluid transfer, in the embodiment where the standpipe is located upstream of the degassing bottle in the vehicle, may include when the vehicle is decelerating and when the vehicle is in an upside-down position.

[0078] Under other conditions, fluid transfer between the degassing cylinder 1302 and the vertical standpipe 1304 can cause the local coolant level 1314 to be at least a threshold value lower than the coolant volume level 1302. Exemplary conditions that can cause such fluid transfer include, in the embodiment where the standpipe is located upstream of the degassing cylinder in the vehicle, when the vehicle is accelerating and when the vehicle is in an upside-down position.

[0079] To adjust an estimate of the local coolant level to an estimate of the coolant volume level, the estimates of vehicle acceleration and position can be used to determine the direction and magnitude of the difference in coolant levels, e.g., via routine 1400. Fig. 14. To estimate. Adjusting the local coolant level to reflect the coolant volume level involves determining a compensation term as an estimate of the difference between the local standpipe level and the coolant volume level. This compensation term may be referred to here as a sloshing or sloshing term. The sloshing term may have an associated sign and magnitude and may be added to the raw standpipe level to form a set estimate of the standpipe level. That is, the sloshing term may be subtracted from or added to the raw standpipe level to form the set estimate of the standpipe level, which estimates what the standpipe level would be if the vehicle were level and the standpipe and volume levels were in equilibrium.Therefore, the set standpipe level serves as an instantaneous estimate of the coolant level in the degassing bottle. The coolant volume level estimate can then be updated based on the set standpipe level estimate. The execution of routine 1400 during a measurement period can depend on whether a valid coolant level measurement exists for that period. For example, routine 1400 can be executed during measurement periods in which an unprocessed standpipe coolant level has been determined, while it cannot be executed during measurement periods in which the coolant level measurements have been marked as invalid, such as at 1128 in routine 1100.

[0080] Routine 1400 begins at 1402, where the power unit controller receives an unprocessed estimate of the local coolant level for the current measurement period. This unprocessed estimate of the local coolant level can be processed by a separate routine, such as routine 1100. Fig. 11. The estimate of the raw level is later used in routine 1400 in combination with a slosh term to determine an estimate of the coolant volume level. After receiving the raw estimate of the coolant level, routine 1400 proceeds to 1404, where estimates of longitudinal acceleration and longitudinal roll can be determined. The longitudinal acceleration estimates can be based on data from an accelerometer or, alternatively, on a time derivative of the speed sensor measurements. The longitudinal roll estimates can be based on data from various sensors. Similarly, at 1406, the controller can determine the estimates for the lateral acceleration and lateral roll of the vehicle.Lateral acceleration estimates can be based on data from an accelerometer or, alternatively, calculated from measurements of speed and wheel speed. Lateral attitude estimates can be based on data from various sensors.

[0081] Based on the acceleration and position estimates in both the longitudinal and transverse directions, performed at 1404 and 1406, an expected or predicted sloshing term can be determined using a transfer function. For example, the transfer function can be expressed by the following equation: expected slosh=(Long. Gain)*[(Long. Acc%)*(Long. Acc.)+(1−Long.Acc.%)*(Long. Att.)]+(Lat. Gain)*[(Lat. Acc.%)*(Lat. Acc.)+(1−Lat.Acc.%)*(Lat.Att.)], where Long. Gain and Lat. Gain are weighting factors for the longitudinal and transverse roll estimates, Long. Acc.% and Lat. Acc.% are weighting factors that weight the relative contributions of acceleration and position in the roll estimate for each direction, Long. Acc. is an estimated longitudinal acceleration, Long. Att. is an estimated longitudinal position, Lat. Acc. is an estimated transverse acceleration, and Lat. Att. is an estimated transverse position. Acceleration estimates can be in units of distance per squared unit time, while position estimates can be in units of degrees of inclination or in static percent of the slope along that axis.The determination of longitudinal and lateral reinforcements can be based on a correlation of the data without acceleration on flat ground against the data from a tilt table, or on vehicle data obtained at a range of accelerations and static positions, and can each be expressed in units of the percentage contribution of the correlation. The relative weighting of acceleration and position can be determined based on the same correlation data using a data fitting procedure (e.g., least squares estimation).

[0082] After determining a predicted sloshing term, the set estimate of the standpipe coolant level (i.e., the unprocessed estimate of the level plus the predicted sloshing term) may be above or below the physical range of the standpipe (as previously discussed regarding...). Fig. (as described in section 11). In these examples, the predicted sloshing can be adjusted based on the standpipe's physical range. If, in an example, the predicted sloshing and the unprocessed standpipe level estimate are added together so that they exceed the standpipe height, adjusting the predicted sloshing based on the standpipe's physical range may involve clipping the predicted sloshing so that the adjusted standpipe coolant level estimate is at the upper threshold of the physical range.In another example, if the predicted sloshing plus the unprocessed estimate of the standpipe level are added so that they are less than the tank height, setting the predicted sloshing may involve clipping the sloshing estimate so that the set estimate of the standpipe coolant level is at the lower threshold of the physical range.

[0083] In addition to an expected sloshing term, an actual sloshing term can be estimated at 1412. An estimate of the actual sloshing can be determined based on a comparison of the raw estimate of the standpipe coolant level with an estimate of the volumetric level. For example, the actual sloshing could be the difference between the raw standpipe coolant level in the current measurement period and the most recent estimate of the volumetric level.

[0084] Based on a comparison between an expected sloshing and an actual sloshing, an assumed sloshing term can be determined at 1414. In an example, determining an assumed sloshing in the signed direction of the expected sloshing might involve choosing the lower absolute value of the actual sloshing and the compensated level than the assumed sloshing. This example is discussed below with respect to Fig. 16 further explained. If both the untrimmed expected sloshing and the actual sloshing are within the physical range of the standpipe, and the magnitude of the expected sloshing is greater than the magnitude of the actual sloshing, then, in another example, the expected sloshing can be trimmed based on the actual sloshing and then applied as the assumed sloshing. This example is further explained below with regard to Fig. 17 explained further.

[0085] After determining an assumed sloshing rate for the measurement period, this assumed sloshing rate can be applied at 1416 to the raw standpipe level estimate to determine the setpoint estimate of the standpipe coolant level. The coolant volume level estimate can then be updated at 1418 based on the setpoint estimate of the standpipe coolant level. In an example, a filter can be used to integrate the setpoint estimate of the standpipe coolant level from the current measurement period into the long-term coolant volume level estimate.Filtering the set estimate of the standpipe level can include filtering through a low-pass filter based on a variable time constant. This time constant is determined based on both the sign and magnitude of the difference between the instantaneous slosh-compensated reading and the long-term volume level estimate, as well as the time interval between the last valid reading and the current valid and slosh-compensated reading. In this way, temporary changes in the coolant level can be smoothed, resulting in a more stable estimate of the coolant volume level.

[0086] Routine 1400 then continues to 1420, where a sensor diagnosis can be performed based on a comparison of the expected and actual sloshing terms for the measurement. For example, the expected sloshing integral and the actual sloshing integral can each be updated based on the expected and actual sloshing terms for the measurement period. These integrals can be incremented whenever expected or actual sloshing is detected and can be decremented by a fixed amount during each measurement period. Sensor degradation can be calculated based on the ratio of the two integrals and is described with respect to... Fig. 15 further described.

[0087] Fig. 15 provides a routine 1500 for determining whether an ultrasonic level sensor in a vertical standpipe (such as the ULS 362 according to Fig. 3) has deteriorated. The routine is based on a comparison of the amounts of expected and actual sloshing accumulated over time. The accumulation of expected and actual sloshing amounts can be characterized by an integral of expected sloshing and an integral of actual sloshing. By comparing these integrals, a force machine controller can determine whether more or less sloshing than expected has been detected during the period, and under some conditions, it can indicate sensor deterioration based on this comparison.

[0088] Routine 1500 begins at 1502, where the value of the integral of the expected sloshing can be incremented if expected sloshing has been detected during the measurement period. The motion parameters can be adjusted, for example, at 1408. Fig. 14. Specify the amount of expected sloshing, where the integral of expected sloshing can be incremented by an amount based on the amount of expected sloshing during the measurement period. Similarly, if actual sloshing has been detected during the measurement period, the value of the integral of actual sloshing can be incremented at 1504. The amount by which the integral of actual sloshing is incremented can be based on the amount of actual sloshing detected. Based on the comparison of the two integrals, it can be determined that the ultrasonic level sensor is degraded due to excessive noise if a first set of conditions is met, while it can be determined that it is degraded due to a blocked measurement if a second set of conditions is met.

[0089] At 1506, both the integral of expected sloshing and the integral of actual sloshing can be decremented by a predetermined amount. In one example, each integral can be decremented by the same fixed amount in each measurement period. This fixed amount is determined based on a baseline value of the integration per loop, measured under verified horizontal conditions without acceleration, where there is less than a lower threshold value of sloshing, thus establishing a baseline noise level for the computation.In another example, the integral of the actual sloshing in each measurement period can be decremented by a first fixed amount, while the integral of the expected sloshing in each measurement period can be decremented by a second fixed amount. The first amount is determined based on a baseline value of the integration per loop, measured under verified horizontal conditions without acceleration, where there is no or limited sloshing. This establishes a baseline noise level for the computation, while the second amount is a smaller fraction (e.g., 80%) of the first value. In this way, the decrement rate of the expectation integral for anticipating any amount of sloshing during each measurement period is affected.In another example, each integral can be decremented by the same variable amount in each measurement period. This variable amount is determined for each measurement period based on the same conditions as above to establish a basis. Furthermore, it incorporates varying the decrement rate based on a magnitude of expected sloshing, which is immediately calculated based on the weighted combination of changes in longitudinal and lateral acceleration and attitude. In yet another example, the integral of expected sloshing in each measurement period can be decremented by a first variable amount, while the integral of actual sloshing in each measurement period can be decremented by a second variable amount. The first and second amounts are determined based on the same principles as the other combination examples above.Other possibilities for decrementing include decrementing one integral by a fixed amount while decrementing the second integral by a variable amount.

[0090] After each integral has been incremented based on the amounts of sloshing detected during the measurement period and decremented based on one of the exemplary basic noise compensations above or a similar compensation, a ratio of the integral of the actual sloshing to the integral of the expected sloshing can be determined at 1508. In one example, the magnitude of the integral of the actual sloshing can be divided by the magnitude of the integral of the expected sloshing, and this number can be used as the ratio of the two.

[0091] At 1510, this ratio is compared to an upper threshold. The upper threshold ratio can be determined based on measuring the largest ratios seen in a test that physically highlights the amount of sloshing within the standpipe (e.g., positioning the vehicle on a shaker table and operating the table at various amplitudes / frequencies to find the worst case resonant with the measured sloshing). Alternatively, the upper threshold ratio can be determined by directly introducing an electrical noise signal into the level sensor input of the electronic control module. A ratio greater than the upper threshold indicates that more sloshing than expected was detected by more than a threshold amount.If the ratio is greater than the upper threshold, routine 1500 can continue to 1512, where the controller can indicate that the ultrasonic level sensor has degraded due to noise. After indicating the sensor degradation due to noise, routine 1500 ends.

[0092] If the ratio is not greater than the upper threshold, routine 1500 continues to 1514, where the ratio of 1508 can be compared to a lower threshold. The lower threshold can be determined based on performing one or more drive cycles (e.g., either the FTP or the US06), each conducted with the standpipe / degassing bottle nearly empty, full, and half full on level ground before each test. These tests involve completely sealing either the upper or lower standpipe hose to prevent gas or fluid exchange during the drive cycle. Consequently, the lower threshold can represent a baseline noise level. The lowest ratios observed from these tests are used to establish the lower threshold level.A ratio that is smaller than a lower threshold may indicate that more than a threshold amount less sloshing was detected than expected.

[0093] If the ratio is less than the lower threshold, routine 1500 can proceed to 1516, where the controller can indicate that the ultrasonic level sensor may be blocked or that fluid transfer between the degassing bottle and the vertical standpipe may be physically obstructed. The controller can differentiate between these two deteriorations based on waiting until both a predetermined time and distance have been traversed before determining whether the disturbance has cleared, and consequently suggest that the ratio is low due to the obstruction. If the ratio is not less than the lower threshold, routine 1500 proceeds to 1518, where the sensor deterioration is not indicated, and routine 1500 then terminates.

[0094] Fig. Section 16 provides a control scheme 1600 for determining an assumed sloshing, applying the assumed sloshing to the unprocessed standpipe coolant level to determine a set standpipe coolant level, and updating a coolant volume level based on the set standpipe coolant level. Data from motion sensors, such as an accelerometer 1602, a position sensor 1604, a vehicle speed sensor 1606, and a wheel speed sensor 1608, can be used at 1610 to determine longitudinal acceleration, lateral acceleration, longitudinal position, and lateral position. In some examples, both longitudinal and lateral acceleration can be determined based on data from a single accelerometer. In other examples, longitudinal and lateral acceleration can be determined from separate accelerometers.Similarly, the longitudinal and lateral positions can be determined by one or more position sensors. In 1612, the variable 1610 is used as input to a function that determines an expected sloshing 1614. In an example, the function 1612 can be expressed by the equation given above regarding . Fig. As described in section 14. The expected sloshing 1614 can then be clipped at 1620, whereby an integral 1644 of the expected sloshing based on the expected sloshing 1614 can also be incremented. The integral 1644 of the expected sloshing is described in more detail below. The clipping 1620 can be based on the physical range of the standpipe 1618, as described above. Fig. As described in section 14, the expected sloshing can be stored in the memory of controller 1616 and can be retrieved from the memory of controller 1616. Truncating the expected sloshing 1614 at 1620 results in a rationalized expected sloshing 1622.

[0095] In addition to the rationalized expected sloshing 1622, an actual sloshing 1628 can be determined based on the difference 1626 between the unprocessed standpipe coolant level 1624 and the coolant volume level 1625. The coolant levels 1624 and 1625 can be accessed via the controller 1616. The integral 1646 of the actual sloshing can be incremented based on the actual sloshing 1628. The integral of the actual sloshing is described in more detail below. The rationalized expected sloshing 1622 and the actual sloshing 1628 can serve as inputs to the compensator 1630. The compensator 1630 can determine an assumed sloshing 1632 based on the inputs 1622 and 1628.

[0096] In one example, the compensator 1630 can compare the sloshes 1622 and 1628, applying the rationalized expected slosh 1622 as the assumed slosh 1632 under a first set of conditions, and applying the actual slosh 1628 as the assumed slosh 1632 under a second set of conditions. The first set of conditions might include, for example, that the sloshes 1622 and 1628 have the same sign (i.e., both are estimates of a positive magnitude of slosh or both are estimates of a negative magnitude of slosh) and that both sloshes are within the physical range of the standpipe 1618, but that the rationalized expected slosh 1622 is of a smaller magnitude than the actual slosh 1628.The second set of conditions may include that the sloshes 1622 and 1628 have the same sign and that both sloshes are within the physical range of the standpipe 1618, but that the actual slosh 1628 is of a smaller size than the rationalized expected slosh 1622.

[0097] In another example, the compensator 1630 can set the rationalized expected sloshing 1622 based on the actual sloshing 1628 and apply the set amount of sloshing as the assumed sloshing 1632. Setting the rationalized expected sloshing 1622 based on the actual sloshing 1628 may involve applying only a fraction of the rationalized expected sloshing 1622 as the assumed sloshing 1632 if the expected sloshing 1622 is greater than the actual sloshing 1628. The actual sloshing 1628 may be less than the rationalized expected sloshing 1622 if fluid exchange between the degassing bottle and the standpipe is physically prevented.By applying only a fraction of the rationalized expected sloshing as the assumed sloshing when the rationalized expected sloshing is greater than the actual sloshing, the accuracy of an estimation of the coolant volume level can be improved. If the expected sloshing 1622 is less than the actual sloshing 1628, adjusting the rationalized expected sloshing 1622 based on the actual sloshing 1628 can involve compensating only by the expected amount, where the expected amount is a conservative amount based on a predefined mapping of the vehicles' tendency to slosh.

[0098] The assumed sloshing 1632 can be applied to the unprocessed standpipe coolant level 1634 to determine the set standpipe coolant level 1638. For example, applying the assumed sloshing 1632 to the unprocessed standpipe coolant level 1634 can involve adding the assumed sloshing 1632 to the unprocessed standpipe coolant level 1638. The filter 1640 can update the coolant volume level 1639 (accessible via the controller 1616) based on the set standpipe coolant level 1638, thereby determining the updated estimate 1642 of the coolant volume level. Filtering the coolant volume level 1639 based on the set standpipe coolant level 1638 can determine a time constant based on the total magnitude of the sloshing compensation applied to the instantaneous level measurement (e.g.more filtering if more compensation is applied) and furthermore based on the signed quantities of the level measurement of the set standpipe coolant level 1638 and the coolant volume level 1639. The coolant condition 1660 can then be updated based on the updated estimate 1642 of the coolant volume level, as with respect to . Fig. 18 is described in more detail.

[0099] Returning to the integral 1644 of the expected sloshing, the integral can be incremented based on the magnitude of the expected sloshing 1614. For example, the integral 1644 of the expected sloshing can be incremented by an amount directly proportional to the expected sloshing 1614. Similarly, the integral 1646 of the actual sloshing can be incremented based on the magnitude of the actual sloshing 1628. The integral 1644 of the expected sloshing and the integral 1646 of the actual sloshing can be decremented at 1645 and 1647, respectively. In one example, each integral can be decremented by the same fixed amount at each measurement period, the fixed amount being based on the measurements taken at 1506. Fig. The compensation procedure described in section 15 is used to determine the sensor state. After decrementing integrals 1644 and 1646 at 1645 and 1647, the sensor state 1650 can be determined, at least partially, based on these integrals. For example, the ratio of the integral 1646 of the actual sloshing, the magnitude of the integral of the actual sloshing, can be divided by the magnitude of the integral of the expected sloshing. Determining the sensor state can then be based on comparing this ratio with either an upper or a lower threshold.

[0100] Fig. Figure 17 presents illustrations of various sloshing conditions to which the compensator was subjected in 1630. Fig. 16 can be encountered, ready. The graphs 1710, 1720, 1730, 1740 show fluid levels based on the estimated sloshing (the dashed lines) and the actual sloshing (the solid lines). In 1710, the expected sloshing 1712 is positive and greater than the maximum physical level of the standpipe, while the actual sloshing 1714 is positive and at the maximum physical level of the standpipe. Under such conditions, the actual sloshing 1714 can be used as the assumed sloshing for the measurement period, since it may be the case that a temporary blockage in a hose (e.g., a fluid trap) or the actual end of the vertical standpipe (e.g., due to the stacking) physically limited the amount of sloshing.

[0101] At 1720, both the expected sloshing (1722) and the actual sloshing (1724) are positive and within the physical range of the standpipe, with the magnitude of the expected sloshing (1722) being greater than the magnitude of the actual sloshing (1724). Under such conditions, only a fraction of the expected sloshing can be applied as the assumed sloshing for the measurement period.

[0102] In 1730, both the expected sloshing in 1732 and the actual sloshing in 1734 are positive, with the magnitude of the expected sloshing in 1732 being smaller than that of the actual sloshing in 1734. Under such a condition, the expected sloshing in 1732 can be used as the assumed sloshing for the measurement period.

[0103] At 1740, both the expected sloshing (1742) and the actual sloshing (1744) are negative and within the physical range of the standpipe. Under such conditions, the actual sloshing (1744) can be used as the assumed sloshing for the measurement period, as a temporary blockage of the hose (e.g., a fluid trap) may be present. Choosing the smaller sloshing value prevents overcompensation for a model of expected sloshing with inaccurate estimates of the acceleration gain or position for the sloshing, or for a temporarily blocked hose.

[0104] Fig. Reference 18 presents a routine 1800 for updating a coolant state based on the coolant volume level estimate and the current coolant state. The updated coolant volume level estimate can correspond to one or more coolant states. For example, the coolant volume level estimate can be OK, LOW, EMPTY, UNKNOWN / DECREASE, and FAILURED. In this example, the coolant volume level estimate can be OK if it is above a higher threshold level, and LOW if it is below the higher threshold but above a lower threshold. The coolant volume level estimate can also be EMPTY if it is below a lower threshold. Additionally, a mid-threshold can be included, as described below with respect to references 1822 and 1826.In some examples, routine 1800 can only update the coolant state if a coolant volume level estimate corresponding to a different coolant state has persisted for longer than a threshold duration. Routine 1800 can be used with a coolant system, such as the one described in the... Fig. 2-9 has been described, and can be performed during any measurement period in which a valid estimate of the coolant volume level is determined, after the estimate of the coolant volume level has been updated (such as via routine 1400 or control scheme 1600).

[0105] Routine 1800 begins at 1802, where the coolant volume level estimate (1804), the current coolant condition (1806), and the temperature data (1808) are received from a power engine controller. At 1810, the controller can determine if the coolant system is faulty. Conditions indicating a coolant system fault can include a lost connection to the controller's area network, no echoes received during the measurement period, or a power engine temperature exceeding an upper threshold. If a coolant system fault is determined at 1810, routine 1800 proceeds to 1812, where the controller can indicate that the coolant level is faulty. Routine 1800 can then update the coolant condition at 1832 based on the current coolant level and condition.If it is determined at 1810 that the cooling system is not malfunctioning, the routine continues from 1800 to 1814.

[0106] Further on at 1814, the controller can determine whether the ultrasonic level sensor is degraded or whether the coolant level is unknown during the current measurement period. Both conditions can correspond to a coolant level of UNKNOWN / DEGRADED. A degraded ultrasonic level sensor can be determined if, for example, the power unit controller previously indicated a noisy or blocked sensor at 1512 or 1516 in routine 1500. Alternatively, sensor degradation can be determined if the expected amount of sloshing indicates that the level of acceleration / position of the vehicle currently occurring is too high to compensate for (i.e., if the expected sloshing indicates a temporary out-of-range reading). The coolant level can be determined to be UNKNOWN / DEGRADED if, for example,the unprocessed estimate of the standpipe coolant level was found to be outside the physical range of the standpipe by more than a threshold amount, as with regard to 1126 after . Fig. 11, or alternatively, if the expected sloshing for the measurement period is greater than a threshold value, the threshold being determined based on the expected sloshing being greater than a percentage of the total height of the standpipe (e.g., plus or minus 25 mm in a 100 mm standpipe). Additionally, the coolant level may be determined to be UNKNOWN if an insufficient number of valid pulse echoes have returned, but not for sufficient measurement periods to set the coolant level to a detected FAILURED state for the sensor. If the ultrasonic level sensor is determined to be degraded, or if the estimate of the coolant volume level during the measurement period is determined to be unknown, the controller may indicate at 1816 that the coolant level is UNKNOWN / DEGRADED.Routine 1800 can then update the coolant status at 1832 based on the current coolant level and condition, as described in more detail below. If, back at 1814, the conditions do not indicate that the ultrasonic sensor is degraded, and the coolant volume level estimate is known, routine 1800 continues to 1818.

[0107] At 1818, the coolant volume level estimate is compared to an upper threshold level to determine if the coolant level is OK. The upper threshold level can be determined based on the predefined correlation of the sensor measurement when a vehicle stationary on level ground is filled to the lowest acceptable factory-recommended fill level. If the coolant volume level estimate is above the upper threshold level, the current coolant level can be reported as OK at 1820. In some examples, the current coolant level can only be reported as OK if the coolant volume level estimate is more than a predefined amount above the upper threshold level. Routine 1800 can then update the coolant status at 1832 based on the current coolant level and condition, as described in more detail below.If, returning to 1818, it is not determined that the coolant volume level estimate is above the upper threshold level, the routine continues from 1800 to 1822.

[0108] At 1822, the coolant volume level estimate is compared to a mean threshold level to determine if the coolant level is LOW. It is stated that at 1822, it has already been determined that the coolant volume level estimate is below the upper threshold level. The mean threshold level can also be referred to here as the LOW threshold level. If it is determined that the coolant volume level estimate is above the LOW threshold, it can be stated at 1824 that the coolant level is LOW. Routine 1800 can then update the coolant condition at 1832 based on the current coolant level and condition, as described in more detail below. If, back at 1822, it is not determined that the coolant volume level estimate is above the mean threshold level, routine 1800 continues to 1826.

[0109] At 1826, the coolant volume level estimate is compared to a lower threshold level to determine whether the coolant level is LOW or EMPTY. The lower threshold level can also be referred to here as the EMPTY threshold. It is reported that at 1826, the coolant volume level estimate was determined to be below the LOW threshold. Consequently, at 1826, it is determined whether the coolant volume level estimate is between the LOW and EMPTY thresholds or below the EMPTY threshold. If the coolant volume level estimate is below the EMPTY threshold, at 1830, it is reported that the coolant level is EMPTY. Routine 1800 can then update the coolant status at 1832 based on the current coolant level and status, as described in more detail below.If, returning to 1826, it is determined that the coolant volume level estimate is above the lower threshold level, the routine continues from 1800 to 1828, where the coolant level is determined based on the coolant condition.

[0110] Specifically, at 1828, the controller can indicate that the coolant level is EMPTY if the coolant volume level estimate is above the EMPTY threshold but below the OK threshold, and the coolant state is EMPTY. If the coolant volume level estimate is above the EMPTY threshold and the coolant state is OK, the controller can indicate that the coolant level is OK. In this way, the coolant state cannot be changed from EMPTY to LOW until the coolant volume level estimate is above the OK threshold.

[0111] In version 1832, the coolant condition can be updated based on the coolant level. In some examples, the coolant condition can only change after a coolant level indicating a new coolant condition has persisted for a threshold duration. This improves coolant condition consistency by preventing changes based on short-term fluctuations in the coolant level around a threshold. Because changing a coolant condition can involve adjusting engine parameters, a consistent coolant condition can improve engine operating conditions. In one example, the threshold duration could be based on a threshold number of measurement periods and / or an engine coolant temperature and / or an engine speed and / or a vehicle speed and / or an estimated coolant level and / or a current coolant condition.This threshold duration can differ for each coolant condition or, alternatively, for each set of coolant conditions. As a non-restrictive example, setting the coolant condition from OK to LOW might require specifying a LOW coolant volume level during a different threshold number of measurement periods than setting the coolant condition from LOW to EMPTY might require specifying an EMPTY coolant volume level.

[0112] In some examples, restrictions may be imposed on changing coolant states. For instance, the coolant state can only change to EMPTY if the coolant level was reported as EMPTY during a first threshold number of measurement periods, and was not reported as either LOW or OK during a second threshold number of measurement periods, where the second threshold is greater than the first. In this way, temporary drops into an EMPTY range can be discarded due to the false detection of an EMPTY state. Furthermore, the coolant state can only change to EMPTY after vehicle movement has been detected and it has been determined that the vehicle is in gear during the current key cycle.In this way, a vehicle operator can fill the system with coolant and allow it to move to a detected full OK state without having to continuously reset the control module to leave the EMPTY state if required.

[0113] At 1834, the engine's operating parameters are set based on the updated coolant condition. In some examples, the coolant condition may not have been updated during the measurement period, and the engine parameters may have been retained from the previous measurement period. However, if the coolant condition has been updated, restrictions can be imposed on or lifted from the engine's operating parameters. For example, if the coolant condition has been updated from OK to EMPTY, commands for engine loads above a threshold load may be disabled while the coolant condition remains EMPTY to prevent overheating of the engine components. Setting the engine's operating parameters based on the coolant condition is described below with regard to... Fig. 19 described in more detail. Then the routine ends at 1800.

[0114] Fig. Section 19 provides a routine 1900 for restricting the operating parameters of the power machine based on the coolant state determined by routine 1800. Routine 1900 can be executed for any measurement period, e.g., at 1834 of routine 1800. A power machine controller can contain a set of restriction modes and can select a mode from the set based on the coolant state and the duration for which the coolant system has been in that state.Selecting a restriction mode can include limiting an engine load to remain below an upper threshold, reducing the injection pulse width for one or more fuel injectors by a threshold amount, completely eliminating fuel injection for one or more fuel injectors, forcing the engine to operate in an idle mode, and / or displaying messages to the vehicle operator providing information about the coolant volume level and the selected restriction mode. Displaying messages to the vehicle operator can also indicate any limitations imposed on the operation of the engine / transmission (e.g., limitations on power, torque, engine speed, available gears, etc.).The selection of a restriction mode can also include indicating that coolant needs to be added if it is low, or indicating an immediate need to stop and add coolant if it is empty. Furthermore, selecting a restriction mode may include tracking the duration the engine has operated under the current restriction mode.

[0115] Routine 1900 begins at 1902, where the coolant state is retrieved from the power unit controller. Retrieving the coolant state may include retrieving the duration for which the current coolant state was active. At 1904, it is determined whether the coolant state has changed during the current measurement period. If the coolant state has changed, routine 1900 continues to 1908, where a restriction mode can be selected based on the coolant state and its duration. Selecting the restriction mode is described in more detail below. If the coolant state has not changed during the current measurement period, routine 1900 continues to 1906.

[0116] At step 1906, the duration for which the current coolant state has been active is compared to one or more threshold durations. Additionally, the duration for which the current restriction mode has been active can be compared to one or more threshold durations. If a threshold duration has not been reached, routine 1900 continues to step 1910, where operation in the current restriction mode can be maintained. Routine 1900 can then terminate.

[0117] If a threshold duration is reached back at 1906, routine 1900 continues to 1908, where a restriction mode can be selected based on the coolant condition and the duration of that condition. It is stated that 1908 can also be reached if the coolant condition has changed during the current measurement period. In an example, the set of restriction modes from which the engine controller can select may include at least a first, a second, and a third mode. In the first restriction mode, the engine controller can simply inform the vehicle operator that the coolant volume level is low and that the vehicle should be taken to a dealership, without imposing any restrictions on the engine's operating parameters, such as engine load and fuel injection.Selecting the second restriction mode can include setting an upper threshold for engine loads and limiting fuel injection to one or more cylinders by eliminating the fuel injection pulse width for those cylinders. The third restriction mode can include the restrictions of the second mode and can further restrict the engine to operate only in an idle mode.

[0118] In some examples, operation in a specific restriction mode cannot be exited until certain conditions are met. In one example, the second restriction mode can only be exited when the engine is restarted. Such an example might also include exiting operation in the third restriction mode when visiting a dealership. In such examples, the selection of a restriction mode at 1908 might also be based on the current restriction mode. For example, the engine might be operating in the second restriction mode, with the current coolant condition indicating operation in the first restriction mode. However, the engine controller cannot select to operate in the first mode based on the current operation in the second restriction mode.

[0119] Selecting a restriction mode in 1908 may include selecting the aforementioned first restriction mode if the coolant condition is LOW or EMPTY. Selecting the first restriction mode may involve operating in the first restriction mode for a threshold duration and selecting either the second or third restriction mode based on the engine conditions after a threshold duration.

[0120] Selecting a constraint mode at 1908 can alternatively include operating in the second constraint mode if the coolant state has been EMPTY for more than one threshold duration. Selecting the second constraint mode can include operating in the second constraint mode for one threshold duration and selecting the third constraint mode after the threshold duration. The power machine controller can also choose to operate in the second constraint mode if the last known state of the system was EMPTY and the current state has been UNKNOWN / DECREASE for one threshold duration, as this condition can be considered functionally equivalent to EMPTY.

[0121] Selecting a restriction mode on the 1908 can also include operating in the third restriction mode if the coolant condition has been EMPTY for more than a threshold duration. Selecting the third restriction mode can include operating in this mode until the vehicle has been taken to a dealership. The controller can only select to operate in the third restriction mode if the coolant condition has been confirmed as EMPTY. In this way, the engine's operating parameters can be restricted to prevent overheating.

[0122] The technical effect of using a system configured with a coolant overflow tank having an internal recess to hold fluid, and a vertical, hollow tube positioned outside the tank also containing an internal recess to hold fluid (the lowest level of which is positioned vertically below the lowest level of the tank's internal recess), and a sensor coupled to the lowest level of the tube's internal recess, is that the coolant level in the tank can be inferred more accurately. The fluidic coupling of the standpipe to the overflow tank allows the fluid levels in the two containers to equalize, thus enabling the fluid level in the tank to be reflected in the fluid level of the vertical tube.By estimating the fluid level in the vertical tube using ultrasonic signals and the detection of their echoes, the sensor output is not coarsely affected by distortions that can influence the volumetric fluid reservoir, such as variations in temperature and motion. Furthermore, the technical benefit of setting an estimate of the fluid level in the vertical, hollow standpipe based on the vehicle's motion parameters is that the fluid level can be better compensated for variations due to sloshing, and a vehicle actuator can be adjusted in response to the more accurate fluid level estimate. This also reduces erratic fluid level estimates generated by fluid sloshing.By limiting engine power based on the estimated fluid level over a given period, engine overheating due to low coolant levels in the reservoir can be reduced. Furthermore, the unwanted triggering of fault modes due to inaccurate low readings can also be avoided. Enabling a processor to estimate the fluid level in the standpipe based on raw and / or processed data generated by the ultrasonic sensor improves the accuracy and reliability of the estimate.More specifically, the technical effect of receiving both unprocessed echo times and processed fluid level data from the sensor coupled into the vertical pipe, and generating a fluid level estimate based on the unprocessed echo times and vehicle sensor data under some conditions, while under other conditions the fluid level estimate is generated based on the processed data, is that the unreliable unprocessed data can be discarded and not used to estimate the fluid level. This increases the weighting of reliable data in the final estimate. Furthermore, the sensor output power can be optimized based on the type of unprocessed data collected by the sensor.Specifically, the technical effect of periodically transmitting a sensor signal from the bottom to the top of a vertical pipe, receiving an echo of the transmitted signal at the sensor, and adjusting the power of the periodically transmitted signals based on the average duration between transmission and reception is that the sensor power can be adjusted to improve the number and quality of first-order echoes while reducing the number of second-order echoes. This improves the accuracy and reliability of the fluid level estimation while also providing the benefits of reduced power consumption. Overall, coolant levels in an engine cooling system can be better monitored, which improves engine performance.

[0123] It should be noted that the exemplary control and estimation routines contained herein can be used with various configurations of the power machine and / or vehicle system. The control procedures and routines disclosed herein can be stored as executable instructions in non-volatile memory and can be executed by the control system, including the controller, in combination with the various sensors, actuators, and other power machine hardware. The specific routines described herein can represent one or more of any number of processing strategies, such as event-driven, interrupt-driven, multitasking, multithreading, and the like. As such, the illustrated various actions, operations, and / or functions can be executed in the illustrated order, in parallel, or, in some cases, omitted.Likewise, the processing sequence is not necessarily required to achieve the features and advantages of the exemplary embodiments described herein, but is provided for ease of illustration and description. One or more of the illustrated actions, operations, and / or functions can be performed repeatedly, depending on the specific strategy employed. Furthermore, the described actions, operations, and / or functions can graphically represent code to be programmed into the non-volatile memory of the computer-readable storage medium in the power machine control system, the described actions being executed by carrying out the instructions in a system that includes the various components of the power machine hardware in combination with the electronic controller.

[0124] It is clear that the configurations and routines disclosed herein are exemplary and that these specific embodiments are not to be considered limiting, as numerous variations are possible. The above technique can be applied, for example, to V-6, I-4, I-6, V-12, Boxer-4, and other types of power engines. The subject matter of this disclosure includes all novel and non-obvious combinations and sub-combinations of the various systems and configurations and other features, functions, and / or properties disclosed herein.

[0125] The following claims specifically describe certain combinations and subcombinations that are considered novel and not obvious. These claims may refer to "one" element, "a first" element, or its equivalent. Such claims should be understood as including one or more such elements and neither requiring nor excluding two or more such elements. Further combinations and subcombinations of the disclosed features, functions, elements, and / or properties may be claimed by amending the present claims or by presenting new claims in this or a related application.Such claims, whether their scope of protection is broader than, narrower than, or equal to the scope of protection of the original claims, or differs from the scope of protection of the original claims, are also considered to be included in the subject matter of the present disclosure. Key to symbols

[0126] Fig. 11 1101 Beginning 1102 Receiving sensor data 1104 Number of qualified echoes 1106 First and second order echo times 1108 sensor-processed level estimation 1110 Coolant temperatures of the sensor circuit and the standpipe 1112 Resting conditions and a high number of qualified echoes? 1114 Apply an estimate from the sensor as an unprocessed fluid level in the standpipe 1116 Have enough first-order echoes been received to qualify locally? 1118 Misidentified Second Order Echoes? 1120 Using the second-order echoes in misidentified sets as first-order echoes 1122 Sufficient first-order echoes received to qualify locally? 1124 Process the unprocessed sensor data to determine the level ( Fig. 12) 1126 Estimated level within the threshold of the physical range? 1128 Mark invalid measurement for a data period 1130 Do not update the level estimate based on the current data period 1132 Use the latest estimate of the volume level 1134 Estimate somewhat outside the physical range? 1136 Trim the estimate based on the physical range 1138 Determine the average of the level calculations 1140 Apply the average as the unprocessed fluid level in the standpipe 1142 Estimate the volume level based on the unprocessed level and the assumed sloshing ( Fig. 14) 1144 End

Claims

[1] Procedure comprising: Estimating a fluid level (1710, 1720, 1730, 1740) in a coolant reservoir based on a sensor coupled into a vertical standpipe (210, 310, 1304) aligned parallel to the coolant reservoir, the standpipe (210, 310, 1304) being fluidly coupled to the coolant reservoir at both an upper and a lower location; and Limiting engine power based on the estimated fluid level (1710, 1720, 1730, 1740). [2] The method of claim 1, wherein limiting based on the estimated fluid level (1710, 1720, 1730, 1740) comprises limiting based on the estimated fluid level (1710, 1720, 1730, 1740) with respect to a first upper threshold and a second lower threshold. [3] The method of claim 2, wherein limiting comprises limiting by a first amount when the estimated fluid level (1710, 1720, 1730, 1740) is below the first threshold and above the second threshold; and limiting by a different second amount when the estimated fluid level (1710, 1720, 1730, 1740) is below both the first and second thresholds. [4] The method of claim 3, wherein the second amount is greater than the first amount, and wherein the second amount is adjusted based on a duration during which the estimated fluid level (1710, 1720, 1730, 1740) remains below the second threshold. [5] The method of claim 4, further comprising indicating a degradation based on the estimated fluid level (1710, 1720, 1730, 1740). [6] The method of claim 5, wherein the indicating includes setting a first diagnostic code when the estimated fluid level (1710, 1720, 1730, 1740) is above the first threshold, setting a second diagnostic code when the estimated fluid level (1710, 1720, 1730, 1740) is below the first threshold and above the second threshold, and setting a third diagnostic code when the estimated fluid level (1710, 1720, 1730, 1740) is below both the first and second thresholds. [7] The method of claim 1, wherein estimating the fluid level (1710, 1720, 1730, 1740) in the coolant reservoir based on the sensor includes transmitting an ultrasonic signal from the sensor to the top of the standpipe (210, 310, 1304), receiving an echo of the ultrasonic signal at the sensor after reflection from a cap coupled to the top of the standpipe (210, 310, 1304); estimating a lapsed duration since transmitting the ultrasonic signal and receiving the echo at the sensor; and estimating the fluid level (1710, 1720, 1730, 1740) in the coolant reservoir based on the estimated duration. [8] The method of claim 7, further comprising predicting fluid slosh based on vehicle motion and adjusting the estimated fluid level (1710, 1720, 1730, 1740) with a compensation term based on the predicted fluid slosh. [9] The method of claim 8, further comprising estimating the actual fluid slosh based on a transient change in the sensor output, wherein the compensation term is based on the predicted fluid slosh with respect to the estimated actual fluid slosh. [10] A method for a prime mover comprising: Distinguishing between the states of a fluid level (1710, 1720, 1730, 1740) in a coolant reservoir based on an output from a sensor coupled to a lower level of an internal recess of a vertical standpipe (210, 310, 1304), the standpipe (210, 310, 1304) being positioned facing the coolant reservoir and further fluidly coupled to the coolant reservoir at both an upper and a lower location, the output being estimated during a duration. [11] The method of claim 10, wherein the duration is adjusted based on the engine coolant temperature, wherein the duration is decreased as the engine coolant temperature increases. [12] The method of claim 10, wherein the distinguishing is further based on a change in the sensor output in response to sloshing caused by the movement of the vehicle. [13] The method of claim 12, wherein distinguishing further based on the slosh includes distinguishing further based on the expected slosh with respect to the estimated slosh, wherein the expected slosh is based on lateral and longitudinal acceleration of the vehicle, wherein the estimated slosh is based on the change in the sensor output. [14] The method of claim 10, further comprising limiting engine power differently based on each condition of the fluid level (1710, 1720, 1730, 1740) in the coolant reservoir. [15] The method of claim 14, wherein the fluid level conditions (1710, 1720, 1730, 1740) include: a first deteriorated condition in which the coolant reservoir is empty; a second deteriorated condition in which the fluid level (1710, 1720, 1730, 1740) of the coolant reservoir is low; a third degraded condition in which the fluid level (1710, 1720, 1730, 1740) of the coolant reservoir is unknown; and a fourth degraded condition in which the sensor is malfunctioning. [16] The method of claim 15, wherein said different limiting includes: in response to the first degraded condition, limiting engine power by a first amount; in response to the second degraded condition, limiting engine power by a second amount; in response to the third degraded condition, limiting engine power by a third amount; in response to the fourth degraded condition, limiting engine power by a fourth amount. [17] The method of claim 10, wherein the distinguishing is further based on at least one of the coolant temperature and the exhaust gas temperature. [18] A coolant system coupled to a vehicle, the coolant system comprising: a coolant overflow tank including a recess for holding a fluid; a vertical hollow tube having an internal recess, the tube positioned adjacent the coolant overflow tank such that a lowest level of the coolant overflow tank is above a lowest level of the internal recess of the tube; a first hose fluidly coupling an upper portion of the coolant overflow tank to an upper portion of the vertical tube; and a second hose fluidly coupling the lowest level of the coolant overflow tank to a lower portion of the vertical tube at a location above the lowest level of the inner recess, wherein a level of fluid in the coolant overflow tank equalizes with a level of fluid in the vertical tube; a first sensor positioned within the internal recess; a second sensor coupled to the vehicle and externally to the vertical tube for estimating a motion parameter of the vehicle; and a processor that is communicatively coupled to the sensor in the internal recess. [19] The system of claim 18, wherein the processor is configured with computer-readable instructions to: estimating a fluid level (1710, 1720, 1730, 1740) in the vertical tube based on an output from the first sensor; Setting the estimated fluid level (1710, 1720, 1730, 1740) based on the output from the second sensor; Inferring a fluid level (1710, 1720, 1730, 1740) in the coolant overflow tank based on the adjusted estimate of the fluid level (1710, 1720, 1730, 1740) in the vertical tube; and Limiting engine power based on the inferred fluid level (1710, 1720, 1730, 1740) with respect to both an upper and a lower threshold, wherein the fluid level (1710, 1720, 1730, 1740) in the vertical tube is estimated during a duration based on the engine coolant temperature, and wherein the inferred fluid level (1710, 1720, 1730, 1740) is further adjusted based on a change in the estimated fluid level (1710, 1720, 1730, 1740) during the duration. [20] The system of claim 18, wherein adjusting the estimated fluid level (1710, 1720, 1730, 1740) based on an output from the second sensor includes estimating an expected slosh based on the output of the second sensor, calculating an actual slosh based on the output of the first sensor, and adjusting the estimated fluid level (1710, 1720, 1730, 1740) with a compensation term based on the actual slosh with respect to the expected slosh, and wherein estimating a fluid level (1710, 1720, 1730, 1740) in the vertical pipe based on the output from the first sensor comprises periodically transmitting a signal from the first sensor to a top of the pipe; receiving an echo of each transmitted signal after reflection from the top of the vertical pipe at the sensor; Estimating an average duration elapsed between sending and receiving;and estimating the fluid level (1710, 1720, 1730, 1740) based on the average duration;

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