Direction change variable brake disengaged

Abstract

A braking system is disclosed. The braking system may include a controller configured to determine a speed threshold based on a deceleration of an output speed of a power system of a machine, the deceleration being caused in part by engagement of one or more brakes of the machine during a direction change in movement of the machine, the speed threshold being the output speed of the power system at which the one or more brakes will be commanded to disengage. The controller may be configured to command the one or more brakes to disengage based on determining that the output speed of the power system meets the speed threshold.

Description

Technical Field

[0001] The present disclosure generally relates to a braking system for a machine and, for example, to variable brake disengagement during a direction change of the machine. Background Art

[0002] Electrohydraulic brake valves can be used in machines such as track-type tractors and other types of earthmoving machines to apply and release braking devices. An electronic controller can control the brake valve by transmitting a brake command current to the brake valve in response to detecting actuation or release of a brake control device by a machine operator. The brake valve responds to the brake command current by changing the pressure within the braking device to tighten or loosen the braking device according to the command. However, in some cases, there may be a time delay between issuing the brake command and the braking device achieving the commanded braking. For example, a time delay associated with hydraulic fluid moving through the brake valve and associated hydraulic passages can occur after a command to disengage the braking device.

[0003] During a direction change of the machine (e.g., from forward to reverse or from reverse to forward), a brake command current commanding the braking device to engage can be automatically transmitted to slow the machine so as to change to the new direction, and at a preset fixed speed, a brake command current commanding the braking device to disengage can be automatically transmitted to allow the machine to move in the new direction. However, due to the time delay associated with disengaging the braking device (e.g., variable time delay) and the specific rate at which the machine decelerates to effect the direction change, the brake command at the fixed speed can cause the braking device to disengage either prematurely or too late. Premature disengagement can reduce the deceleration rate, which can unsettle the machine operator and prolong the direction change. Too late disengagement can cause the machine to stall at zero speed, thereby preventing the machine from moving in the new direction.

[0004] One attempt at a control device for an industrial vehicle that does not produce a speed change shock when changing the traveling direction to the opposite direction is disclosed in U.S. Patent No. 7,097,021 to Takamura et al., issued on August 29, 2006 (“the ’021 patent”). Specifically, the ’021 patent discloses that when changing the traveling direction during vehicle operation, the vehicle is first gradually decelerated by braking applied by the brakes. The ’021 patent also discloses that when the vehicle speed drops below a specified speed, before the vehicle speed reaches zero, both the braking force of the brakes and the engine braking torque generated by engaging the forward clutch or reverse clutch of the transmission corresponding to the selected traveling direction are controlled. The ’021 patent states that as a result, the deceleration torque before the direction reversal and the acceleration torque after the direction reversal are controlled to substantially constant values, such that acceleration fluctuations near the time point of the traveling direction reversal are reduced.

[0005] Although the control device of the '021 patent can solve the speed change shock when the traveling direction of the vehicle is switched, the '021 patent does not solve the problem that the brake disengagement occurs too early or too late due to the time delay associated with disengaging the brake. For example, the '021 patent does not solve the problem associated with commanding the brake to disengage at a fixed speed, which does not take into account the time delay (e.g., variable time delay) associated with disengaging the braking device and / or the specific deceleration rate of the machine performing the direction change.

[0006] The braking system of the present disclosure solves one or more of the above problems and / or other problems in the prior art. SUMMARY OF THE INVENTION

[0007] According to some embodiments, a method may include: determining a speed threshold based on a deceleration of an output speed of a power system of a machine, the deceleration being caused in part by engagement of one or more brakes of the machine during a direction change in movement of the machine, the speed threshold being the output speed of the power system when the one or more brakes are to be commanded to disengage; and commanding the one or more brakes to disengage based on determining that the output speed of the power system meets the speed threshold.

[0008] According to some embodiments, a braking system may include one or more brakes and a controller configured to: identify a command that will cause a direction change; based on identifying the command, determine a speed threshold based on a deceleration of an output speed of a power system, the deceleration being caused in part by engagement of the one or more brakes during the direction change, the speed threshold being the output speed of the power system when the one or more brakes are to be commanded to disengage; and command the one or more brakes to disengage based on determining that the output speed of the power system meets the speed threshold.

[0009] According to some embodiments, a machine may include a power system, one or more brakes, and a controller configured to: determine a speed threshold based on a deceleration of an output speed of the power system and a time delay between a brake command and corresponding disengagement of the one or more brakes, the deceleration being caused in part by engagement of the one or more brakes during a direction change in movement of the machine, the speed threshold being the output speed of the power system when one or more brakes of the machine are to be commanded to disengage; and command the one or more brakes to disengage based on determining that the output speed of the power system meets the speed threshold. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 is a diagram of an exemplary machine described herein.

[0011] Figure 2 is a diagram of an exemplary embodiment described herein.

[0012] Figure 3 is a diagram of an exemplary embodiment described herein.

[0013] Figure 4 is a flowchart of an exemplary process for disengaging a direction-changing variable brake. Detailed Description

[0014] Figure 1 is a diagram of an exemplary machine 10 that includes a controller 12. As Figure 1 shown, machine 10 is embodied as a track-type machine, such as a track-type tractor. Alternatively, machine 10 can be a backhoe loader, skid-steer loader, wheel loader, motor grader, excavator, scraper, agricultural tractor, haul truck, etc.

[0015] As Figure 1 shown, machine 10 can include a frame assembly 14 and a power source 16. The power source 16 can include one or more batteries configured to provide power to machine 10, one or more engines (e.g., diesel engines), one or more generators, etc. For example, the power source 16 can provide power to a power system ( Figure 1 not shown) of machine 10, which can include an electric motor (e.g., an electric motor), a transmission (e.g., an electric transmission, a hydraulic transmission, a mechanical transmission, a continuously variable transmission, etc.), and so on. The power system can be associated with an electric drive system of machine 10 or a continuously variable transmission of machine 10.

[0016] Machine 10 can also include a set of ground-engaging members 18 for propelling machine 10, such as wheels, tracks, rollers, etc. In addition, machine 10 can include an operator cab 20, which can include one or more input devices ( Figure 1 not shown) for controlling and / or monitoring the operation of machine 10, such as one or more buttons, control levers, steering wheels, etc.

[0017] In some embodiments, machine 10 can include a hydraulic pump (not shown). The hydraulic pump can be operatively coupled to the power source 16 to provide pressurized hydraulic fluid to hydraulic cylinders 24 for moving tools and implements (e.g., front attachment 26 and / or rear attachment 28) of machine 10 via a hose 22. The front attachment 26 can include a scraper assembly, etc. The rear attachment 28 can include a ripper assembly, a winch assembly, a drawbar assembly, etc.

[0018] In addition, machine 10 may include a braking system ( Figure 1 not shown in the figure), which is configured to slow down and / or prevent the movement of machine 10. The braking system may include one or more brakes, such as electro-hydraulic brakes. The electro-hydraulic brakes may include an electro-hydraulic brake valve and a braking device controlled by the electro-hydraulic brake valve. For example, the electro-hydraulic brake valve may control the pressure of the hydraulic fluid applied to a piston, and the piston controls the engagement and disengagement of the braking device.

[0019] The controller 12 (e.g., an electronic control module (ECM)) may include one or more memories and one or more processors, and the one or more memories and one or more processors implement operations associated with variable brake disengagement during the direction change of machine 10, as described below in conjunction with Figure 2 the description. For example, the controller 12 may be configured to: identify a command that will cause a direction change of machine 10; based on the identification of the command, determine a speed threshold, the speed threshold being based on the deceleration of the output speed of the power system, the deceleration being partially caused by the engagement of the brakes and / or the deceleration of the power system during the direction change; and command the brakes to disengage based on determining that the output speed of the power system meets the speed threshold.

[0020] The direction change may refer to the process of the moving direction of machine 10 (e.g., through the power system of machine 10, such as through the transmission of machine 10) changing from the forward direction to the reverse direction or from the reverse direction to the forward direction. Therefore, the direction change may start when a command to move in a direction opposite to the current moving direction is given, and may end when starting to move in the opposite direction.

[0021] As described above, provided Figure 1 as an example. Other examples may be different from the examples described in conjunction with Figure 1 the description.

[0022] Figure 2 is a diagram of an exemplary embodiment 200 described herein. As Figure 2 shown, the exemplary embodiment 200 may relate to a braking system of machine 10, which includes a controller 12, a power system 30, an input device 32, and one or more brakes 34, as described above in conjunction with Figure 1 the description. For example, the brake 34 may be an electro-hydraulic brake, which is associated with a time delay between a command to disengage the brake 34 and the corresponding disengagement of the brake 34. The power system 30 may include an electric motor (e.g., an electric motor), a transmission (e.g., an electric transmission, a hydraulic transmission, a mechanical transmission, a continuously variable transmission, etc.), and so on.

[0023] As Figure 2As shown, the controller 12 can receive information related to the speed of the power system 30 (e.g., output speed). Information related to the speed of the power system 30 can include the revolutions per minute (RPM) of the power system 30. The speed of the power system 30 can be associated with the speed of the motor of the power system 30 (e.g., RPM), the output speed of the transmission of the power system 30 (e.g., RPM), etc. Additionally, the controller 12 can receive information related to one or more operator commands provided by the operator of the machine 10 (e.g., via the input device 32). One or more operator commands can relate to a direction change of the machine 10.

[0024] As Figure 2 As shown and as indicated by reference numeral 205, the controller 12 can identify a direction change of the machine 10. That is, the controller 12 can identify that the machine 10 will perform a direction change. The controller 12 can identify the direction change of the machine 10 based on one or more operator commands received by the controller 12 (e.g., via the input device 32). For example, an operator command can command the forward speed of the machine 10, followed by an operator command that commands the reverse speed of the machine 10, thereby enabling the controller 12 to determine the direction change. Other operator commands can additionally or alternatively indicate the direction change of the machine 10.

[0025] Based on identifying the direction change, the controller 12 can command the brake 34 to engage and / or command the power system 30 to decelerate (e.g., the motor, transmission, etc. to decelerate) to effect the direction change. For example, the engagement of the brake 34 and / or the deceleration of the power system 30 can cause the machine 10 to decelerate and cause the speed of the power system 30 to decelerate accordingly, thereby effecting a change in direction in accordance with the direction change. The controller 12 can maintain the engagement of the brake 34 during the direction change until the speed of the power system 30 (e.g., the speed of the motor, transmission, etc.) meets a speed threshold, at which time the controller can command the brake 34 to disengage. As described below, the speed threshold can be based on the deceleration of the power system 30 (e.g., the deceleration of the motor, transmission, etc.) and can thus be variable.

[0026] As shown by reference numeral 210, the controller 12 may determine the deceleration of the powertrain 30 (e.g., during a direction change). For example, the controller 12 may determine the deceleration of the powertrain 30 (e.g., RPM / second) based on information related to the speed of the powertrain 30 (e.g., the speed of the motor, transmission, etc.) (e.g., RPM) as described above. The controller 12 may receive information related to the speed of the powertrain 30 from a speed sensor associated with the powertrain 30 (e.g., associated with the motor, transmission, etc.). Based on the speed of the powertrain 30, the controller 12 may determine the deceleration of the powertrain 30 as the derivative of the speed of the powertrain 30 with respect to time. In some embodiments, the controller 12 may process the determined derivative using one or more filters and / or one or more other signal processing techniques to determine the deceleration. For example, the controller 12 may process the determined derivative using one or more filters to remove noise or perform saturation of the magnitude of the derivative to remove noise.

[0027] As shown by reference numeral 215, the controller 12 may determine a speed threshold (e.g., during a direction change) that represents the speed of the powertrain 30 (e.g., the speed of the motor, transmission, etc.) (e.g., output speed) at which the brake 34 will be commanded to disengage. The speed threshold may be based on the determined deceleration of the powertrain 30. In other words, the controller 12 may determine the speed threshold based on the deceleration of the powertrain 30. Thus, the speed threshold may vary depending on the circumstances due to the change in the deceleration of the powertrain 30.

[0028] Additionally, the speed threshold may also be based on the time delay between the command to disengage the brake 34 and the corresponding disengagement of the brake 34. That is, the time delay between a first time when the controller 12 transmits a command to disengage the brake 34 and a second time when the brake 34 disengages in response to the command. In such cases, the controller 12 may determine the speed threshold as the product of the deceleration and the time delay.

[0029] The time delay may be an estimated value based on one or more properties of the brake 34, such as the temperature of the hydraulic fluid of the brake 34 (e.g., the hydraulic fluid that causes the brake 34 to disengage), the flow characteristics of the hydraulic fluid in the electro-hydraulic brake valve of the brake 34 (e.g., the flow capacity or flow rate of the hydraulic fluid through the electro-hydraulic brake valve), the area of the piston associated with the electro-hydraulic brake valve, the estimated wear amount of the brake 34 (e.g., based on the time elapsed since the previous brake replacement, the distance traveled by the machine 10 since the previous brake replacement, etc.), and so on. Thus, the estimated value of the time delay may vary with temperature and / or the use of the brake 34.

[0030] Additionally, the speed threshold can also be based on an offset value, which can be a constant value greater than or equal to zero. The offset value can be a speed (e.g., RPM) added to the speed threshold (e.g., to ensure that the speed threshold is a speed greater than zero). As described above, the offset value can compensate for delays between the command to disengage the brake 34 and the corresponding disengagement of the brake 34 that are not caused by the properties of the brake 34. For example, the delay can be a software delay, a hardware delay, a delay due to an estimation error, a delay due to a filtering error, etc.

[0031] As shown by reference numeral 220, the controller 12 can transmit a command to disengage the brake 34 (e.g., during a direction change) based on determining that the speed of the power system 30 (e.g., the speed of the motor, transmission, etc.) meets the speed threshold (e.g., the speed of the power system 30 is less than or equal to the speed threshold). For example, the controller 12 can monitor the speed of the power system 30 (e.g., based on information related to the speed of the power system 30 that can be provided to the controller 12 by one or more speed sensors), and can transmit a command to disengage the brake 34 when the speed of the power system 30 meets the speed threshold. In some embodiments, the command can include a flag indicating that the brake 34 will disengage.

[0032] As described above, provided Figure 2 as an example. Other examples may be different from those Figure 2 described in conjunction with

[0033] Figure 3 is a diagram of an exemplary embodiment 300 described herein. Specifically, Figure 3 illustrates an example of brake disengagement during a direction change of a machine (e.g., machine 10) as described elsewhere herein.

[0034] As Figure 3 shown and as represented by line 305, the speed of the power system of the machine (e.g., the power system 30, e.g., the speed of the motor, transmission, etc.) can begin to decrease in response to a commanded direction change of the operator of the machine. For example, as Figure 3 shown, the deceleration of the power system can be caused by engaging one or more brakes (e.g., brake 34) and / or decelerating the power system of the machine (e.g., decelerating the motor, transmission, etc.) in response to the commanded direction change. As represented by line 310, the speed threshold can be determined (e.g., by the controller of the machine) based on the deceleration of the power system, as described above in conjunction with Figure 2 described. The speed threshold can represent the speed of the power system (e.g., the output speed) at which the brake will be commanded to disengage.

[0035] As shown at point 315, during a direction change, the speed of the power system can decrease until the speed of the power system meets a speed threshold. As described above in connection with Figure 2 The controller of the machine can monitor the speed of the power system to determine when the speed of the power system meets the speed threshold.

[0036] Based on the speed of the power system meeting the speed threshold, a command to disengage the brake can be transmitted at a first time 320. For example, the controller can transmit a command to disengage the brake. As Figure 3 shown, a time delay may occur between the first time 320 at which the command to disengage the brake is transmitted and the second time 325 at which the brake disengages in response to the command. However, as Figure 3 shown, despite the time delay, the brake disengages before the speed of the power system reaches zero, as shown at point 330.

[0037] As described above, provided Figure 3 as an example. Other examples may be different from those described in connection with Figure 3 the description.

[0038] Figure 4 is a flowchart of an exemplary process 400 for disengaging a variable brake during a direction change. Figure 4 One or more process blocks of Figure 4 can be performed by a controller (e.g., controller 12). Additionally or alternatively,

[0039] As Figure 4 shown, process 400 can include determining a speed threshold that is based on the deceleration of the output speed of the power system of the machine, the deceleration being caused in part by the engagement of one or more brakes of the machine during a direction change in the movement of the machine (block 410). For example, the controller (e.g., using a processor, memory, storage component, input component, communication interface, etc.) can determine the speed threshold as described above, the speed threshold being based on the deceleration of the output speed of the power system of the machine, the deceleration being caused in part by the engagement of one or more brakes of the machine during a direction change in the movement of the machine. The output speed of the power system can be associated with the motor of the power system or the transmission of the power system.

[0040] In some embodiments, process 400 may further include commanding a direction change during movement of the machine. Additionally or alternatively, process 400 may further include identifying a command that will cause a direction change. A command that will cause a direction change may cause one or more brakes to engage. Additionally, process 400 may further include determining a deceleration of the output speed of the power system based on the output speed of the power system.

[0041] The speed threshold may be the output speed of the power system at which one or more brakes will be commanded to disengage. Additionally, the speed threshold may be based on the deceleration of the output speed of the power system and the time delay between the braking command and the corresponding disengagement of one or more brakes. For example, the speed threshold may be the product of the deceleration of the output speed and the time delay. The time delay may be an estimated value based on the temperature of the hydraulic fluid that causes the corresponding disengagement of one or more brakes. The estimated value may also be based on at least one of the flow characteristics of the hydraulic fluid in the valves of one or more brakes or the estimated wear amount of one or more brakes. Additionally, the speed threshold may be based on an offset value, as described above.

[0042] As Figure 4 also shown, process 400 may include commanding one or more brakes to disengage (block 420) based on determining that the output speed of the power system meets the speed threshold. For example, a controller (e.g., using a processor, memory, output components, communication interfaces, etc.) may command one or more brakes to disengage based on determining that the output speed of the power system meets the speed threshold as described above.

[0043] In some embodiments, process 400 may further include monitoring the output speed of the power system to determine whether the output speed of the power system meets the speed threshold. Additionally, commanding one or more brakes to disengage may cause one or more brakes to disengage before the output speed of the power system reaches zero. One or more brakes may be electro-hydraulic brakes, as described above.

[0044] Although Figure 4 exemplary blocks of process 400 are shown, in some embodiments, process 400 may include additional blocks, fewer blocks, different blocks, or differently arranged blocks compared to those depicted Figure 4 herein. Additionally or alternatively, two or more blocks of process 400 may be executed in parallel.

[0045] Industrial applicability

[0046] The disclosed braking system can be used with any machine that is desired to improve performance during a direction change. In particular, the disclosed braking system can enable the brakes of the machine to disengage while the speed of the machine is approaching zero but before reaching zero. In this way, the machine can have a smooth deceleration during the direction change without suddenly losing deceleration, which can make the operator feel uneasy and prolong the direction change, and may occur due to the premature disengagement of the brakes. In addition, the machine can change direction during the direction change without prolonging the delay at zero speed, which may occur due to the late disengagement of the brakes.

Claims

1. A method, comprising: Determining a speed threshold based on a deceleration of an output speed of a power system (30) of a machine (10), the deceleration being caused in part by engagement of one or more brakes (34) of the machine (10) during a direction change in the movement of the machine (10); The speed threshold being the output speed of the power system (30) at which the one or more brakes (34) are to be commanded to disengage; and Based on determining that the output speed of the power system (30) meets the speed threshold, commanding the one or more brakes (34) to disengage.

2. The method according to claim 1, wherein the one or more brakes (34) are electro-hydraulic brakes.

3. The method according to any one of claims 1-2, wherein commanding the one or more brakes (34) to disengage causes the one or more brakes (34) to disengage before the output speed of the power system (30) reaches zero.

4. The method according to any one of claims 1-3, further comprising commanding a direction change in the movement of the machine (10).

5. The method according to any one of claims 1-4, wherein the output speed of the power system (30) is associated with a motor of the power system (30) or a transmission of the power system (30).

6. A machine (10), comprising: A power system (30); One or more brakes (34); And A controller (12) configured to: Determine a speed threshold based on a deceleration of an output speed of the power system (30) and a time delay between a braking command and corresponding disengagement of the one or more brakes (34), the deceleration being caused in part by engagement of the one or more brakes (34) during a direction change in the movement of the machine (10); The speed threshold being the output speed of the power system (30) at which the one or more brakes (34) of the machine (10) are to be commanded to disengage; and Based on determining that the output speed of the power system (30) meets the speed threshold, command the one or more brakes (34) to disengage.

7. The machine (10) according to claim 6, wherein the time delay is an estimated value based on a temperature of a hydraulic fluid causing the one or more brakes (34) to disengage correspondingly.

8. The machine (10) according to any one of claims 6-7, wherein the estimated value is further based on at least one of flow characteristics of the hydraulic fluid in a valve of the one or more brakes (34) or an estimated amount of wear of the one or more brakes (34).

9. The machine (10) according to any one of claims 6-8, wherein the output speed of the power system (30) is associated with a motor of the power system (30) or a transmission of the power system (30).

10. The machine (10) according to any one of claims 6-9, wherein the speed threshold is further based on an offset value.

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