Control system for engine

Abstract

To provide a control system for an engine capable of suppressing fluctuation of output of the engine.SOLUTION: A control system for an engine includes: a fan that receives power from a rotating shaft of the engine; a mechanical clutch disposed between the engine and the fan; and a control device that controls the output of the engine. The control device acquires the rotational frequency of the fan, acquires the engagement rate of the mechanical clutch from the rotational frequency of the fan, acquires loss output caused by the mechanical clutch corresponding to the engagement rate, and executes output correction control for correcting the output of the engine in accordance with the loss output.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to an engine control system. [Background technology]

[0002] Conventionally, there is known an engine control system equipped with a fan for introducing air into a radiator (see, for example, Patent Document 1). In the engine control system of Patent Document 1, a mechanical clutch using a bimetal and a fluid (silicon in Patent Document 1) is provided between the rotating shaft of the engine and the fan, and when the temperature of the bimetal rises, the clutch is engaged and the fan rotates. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2015-34488 A Summary of the Invention [Problem to be solved by the invention]

[0004] Such mechanical clutches rotate together with the engine shaft, creating friction. Also, the magnitude of friction varies depending on the bimetal and fluid. Therefore, engine control systems using such mechanical clutches have the problem that output tends to vary due to clutch friction.

[0005] An object of the present disclosure is to provide an engine control system capable of suppressing variations in engine output. [Means for solving the problem]

[0006] The engine control system according to the present disclosure includes a fan that receives power from a rotating shaft of an engine, a mechanical clutch arranged between the engine and the fan, and a control device that controls the output of the engine, wherein the control device obtains the rotation speed of the fan, obtains the engagement ratio of the mechanical clutch from the rotation speed of the fan, obtains the power loss due to the mechanical clutch according to the engagement ratio, and performs output correction control that corrects the output of the engine according to the power loss. Effect of the Invention

[0007] According to this engine control system, the power loss due to the fan according to the clutch engagement ratio is obtained, and the engine power is corrected according to the power loss, thereby suppressing the variation in the engine power. [Brief description of the drawings]

[0008] [Figure 1] 1 is a system diagram of an engine control system according to one embodiment of the present disclosure. [Diagram 2] FIG. 2 is a cross-sectional view of a clutch according to one embodiment of the present disclosure. [Diagram 3] 6 is a graph showing fan rotation speed characteristics according to one embodiment of the present disclosure. [Figure 4] FIG. 2 illustrates an example of a map according to an embodiment of the present disclosure. [Diagram 5] 4 is a flowchart showing a control procedure of a control device according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings.

[0010] 1, the engine control system 1 includes an engine 2, a fan 4, a mechanical clutch 6, a radiator 8, a control device 10, and an outside air temperature sensor 12. The engine control system 1 of this embodiment is a system mounted on a vehicle C. The engine control system 1 is accommodated in an engine compartment 14 disposed in the front of the vehicle C.

[0011] The engine 2 is, for example, an internal combustion engine such as a diesel engine. The engine 2 has a rotating shaft 2a. In this embodiment, the rotating shaft 2a is a member connected to a crankshaft of the engine 2. However, the rotating shaft 2a may be a member that is driven from the crankshaft via a pulley and a belt, for example.

[0012] The fan 4 is a member that receives power from the rotary shaft 2 a of the engine 2 to rotate, and introduces outside air into the radiator 8 .

[0013] The mechanical clutch 6 is disposed between the rotating shaft 2a of the engine 2 and the fan 4, and is a device for varying the engagement ratio, which is the rate of power transmission from the rotating shaft 2a to the fan. As shown in Fig. 2, the mechanical clutch 6 of this embodiment has a bimetal 6a, a valve 6b, a storage chamber 6c, a drive chamber 6d, and an inlet hole 6e. When the engagement ratio is 0%, the valve 6b completely blocks the inlet hole 6e.

[0014] In the mechanical clutch 6, when the temperature of the cooling air passing through the radiator 8 rises, the bimetal 6a is heated and deformed. When the bimetal 6a deforms, the rotary valve 6b rotates, and the inlet hole 6e between the storage chamber 6c and the drive chamber 6d opens. When the inlet hole 6e opens, the fluid (silicon in this embodiment) contained in the storage chamber 6c flows into the drive chamber 6d. In the drive chamber 6d, a labyrinth 6h is provided between the outer case 6f to which the fan 4 is fixed and the inner case 6g to which the rotating shaft 2a is fixed. The fluid enters the labyrinth 6h, and transmits the power of the rotating shaft 2a to the fan 4 via the inner case 6g and the outer case 6f by utilizing the viscosity of the fluid and the shear stress according to the viscosity.

[0015] When the temperature of the cooling air further rises, the bimetal 6a deforms further. When the bimetal 6a deforms further, the valve 6b rotates and the opening area of ​​the inlet hole 6e increases. This increases the bonding ratio. When the opening area of ​​the inlet hole 6e reaches its maximum, the bonding ratio becomes 100%.

[0016] As shown in Fig. 3, in such a mechanical clutch 6, as the engine speed ENG_R of the engine 2 increases, the fan speed Fan_R of the fan 4 increases. Also, in the mechanical clutch 6, the higher the engagement ratio, the higher the fan speed Fan_R. Furthermore, even if the engagement ratio of the mechanical clutch 6 is zero, the rotating shaft 2a rotates the fan 4 due to the fluid remaining in the drive chamber 6d (see the graph of the engagement ratio of 0% in Fig. 3).

[0017] The mechanical clutch 6 uses shear stress in the labyrinth 6h according to the viscosity of the fluid, generating resistance (friction) according to the joining ratio. Since the mechanical clutch 6 uses the engine 2 as a power source, this resistance robs the engine 2 of its output. Furthermore, the resistance of each mechanical clutch 6 differs due to variations in the bimetal characteristics and the fluid characteristics.

[0018] As shown in FIG. 1, the radiator 8 is a device for cooling the coolant of the engine 2. The radiator 8 is disposed on the front side of the engine 2 in the vehicle. The fan 4 is disposed between the radiator 8 and the engine 2. The cooling air that has passed through the radiator 8 is introduced into the fan 4. As described above, when the temperature of the cooling air passing through the radiator 8 increases, the engagement ratio of the mechanical clutch 6 increases and the rotation speed of the fan 4 increases. This increases the amount of air passing through the radiator 8. As a result, the coolant is further cooled.

[0019] The control device 10 is a device that controls the output of the engine 2. The control device 10 is actually an ECU (Electronic Control Unit) and is configured by a microcomputer including an arithmetic unit, a memory, an input / output buffer, etc. The control device 10 controls the engine 2 so that the engine 2 is in a desired operating state based on signals from various sensors and devices mounted on the engine 2, as well as maps and programs stored in the memory. Note that the various controls are not limited to processing by software, and can also be processed by dedicated hardware (electronic circuits).

[0020] The control device 10 acquires the fan rotation speed Fan_R of the fan 4, and acquires the clutch engagement ratio CON_R from the fan rotation speed Fan_R. The control device 10 acquires the loss output of the resistance caused by the fan 4 according to the engagement ratio CON_R. In this embodiment, the control device 10 acquires the friction torque obtained by replacing the loss output with torque, and executes torque correction control (an example of output correction control) that corrects the engine output according to the friction torque.

[0021] Specifically, the control device 10 stores a first fan speed Fan_R1 and a second fan speed Fan_R2 as shown in FIG. 3. The first fan speed Fan_R1 is the speed of the fan 4 for each engine speed ENG_R when the mechanical clutch 6 is in an engaged state. The second fan speed Fan_R2 is the speed of the fan 4 for each engine speed ENG_R when the mechanical clutch 6 is in a disengaged state. As shown in FIG. 3, in this embodiment, the mechanical clutch 6 is in an engaged state when the engagement ratio is 100%. The mechanical clutch 6 is in a disengaged state when the engagement ratio is 0%. That is, in this embodiment, the control device 10 stores the graph in FIG. 3.

[0022] The control device 10 acquires the actual fan rotation speed Fan_Rr, which is the actual rotation speed of the fan 4. The control device 10 may acquire the actual fan rotation speed Fan_Rr from a fan rotation speed sensor 4a (see FIG. 1), or may acquire the actual fan rotation speed Fan_Rr by other methods. The control device 10 further acquires the actual engine rotation speed ENG_Rr, which is the actual rotation speed of the engine 2. The control device 10 acquires the first fan rotation speed ENG_R1 and the second fan rotation speed Fan_R2 at the actual engine rotation speed ENG_Rr from a graph. The control device 10 acquires the joining ratio based on the first fan rotation speed ENG_R1 and the second fan rotation speed Fan_R2.

[0023] More specifically, as shown in the following equation (1), the control device 10 obtains the joining ratio by calculating the ratio of the difference between the actual fan rotation speed Fan_Rr and the second fan rotation speed Fan_R2 to the difference between the first fan rotation speed Fan_R1 and the second fan rotation speed Fan_R2 at the actual engine rotation speed ENG_Rr. CON_R=(Fan_Rr―Fan_R2) / (Fan_R1―Fan_R2) ...(Formula 1) For example, when the actual engine speed ENG_Rr is 1000 rpm, the first fan speed ENG_R1 is 2000 rpm, the second fan speed Fan_R2 is 500 rpm, and the actual fan speed Fan_Rr is 1500 rpm, the joining ratio CON_R is approximately 67%.

[0024] When the control device 10 acquires the joining ratio CON_R, it acquires the friction torque. As shown in FIG. 4, in this embodiment, the control device 10 stores a map in which friction torque corresponding to the joining ratio CON_R and the actual engine speed ENG_Rr is recorded. The control device 10 acquires the friction torque from the map. When the control device 10 acquires the friction torque, it executes torque correction control for adding a torque equivalent to the friction torque to the output of the engine 2. Specifically, the control device 10 calculates a correction torque obtained by adding the friction torque to the engine required torque calculated from the depression amount of the accelerator (not shown) of the vehicle, and the like. The control device 10 acquires values ​​such as the fuel injection amount of the engine 2 corresponding to the correction torque, and controls the output of the engine 2.

[0025] The outside air temperature sensor 12 is a sensor that acquires the outside air temperature Tout in the engine compartment 14 .

[0026] Next, the control procedure executed by the control device 10 will be described with reference to the flowchart of FIG.

[0027] In step S1, the control device 10 determines whether the engine 2 is in a start mode. The start mode is a state in which the engine 2 is started by cranking, for example. In the start mode, the fan speed Fan_R of the fan 4 (or the actual fan speed Fan_Rr) is not stable. For this reason, the control device 10 takes time to calculate the joining ratio CON_R. Therefore, when the control device 10 determines that the engine 2 is in the start mode (YES in step S1), the control device 10 advances the process to step S6 and prohibits torque correction control. When the control device 10 determines that the engine 2 is not in the start mode (NO in step S1), the control device 10 advances the process to step S2.

[0028] In step S2, the control device 10 determines whether the engine 2 is idling. If torque correction control according to the rotation speed of the fan 4 is executed while the engine 2 is idling, the correction torque constantly changes according to the change in the rotation speed of the fan 4. This may cause the engine speed ENG_R (or the actual engine speed ENG_Rr) to hunt, and the combustion of the engine 2 while idling may become unstable. For this reason, if the control device 10 determines that the engine 2 is idling (YES in step S2), the control device 10 advances the process to step S6 and prohibits the torque correction control. If the control device 10 determines that the engine 2 is not idling (NO in step S2), the control device 10 advances the process to step S3.

[0029] In step S3, the control device 10 judges whether the engine 2 is operating in a transient region (transient operation). If torque correction control according to the rotation speed of the fan 4 is executed during transient operation, the calculation for the torque correction control increases the amount of calculation for the fuel injection amount, etc., and the control response deteriorates. In particular, at a predetermined output or more (for example, the accelerator opening is 70% or more), there is a risk that the control response deteriorates due to such an increase in the calculation load. This may lead to, for example, a deterioration in the response of the engine 2 to the accelerator. For this reason, if the control device 10 judges that the engine 2 is operating in a transient region (step S3 YES), the control device 10 proceeds to the process of step S6 and prohibits the torque correction control. If the control device 10 judges that the engine 2 is not operating in a transient region (step S3 NO), the control device 10 proceeds to the process of step S4.

[0030] In step S4, the control device 10 judges whether the outside air temperature Tout of the engine room 14 is equal to or higher than a predetermined temperature Tt. The predetermined temperature Tt is, for example, about 26°C. Below the predetermined temperature Tt, the engine 2 operates in a cold state. For this reason, the engine 2 has a much larger output loss due to stirring resistance of the oil used in the engine 2 than the output loss due to the mechanical clutch 6. If the outside air temperature Tout of the engine room 14 is equal to or higher than the predetermined temperature Tt (YES in step S4), the control device 10 determines that the engine 2 is not in a cold state and proceeds to step S5.

[0031] In step S5, the control device 10 obtains the friction torque as described above, and proceeds to the process of step S1.

[0032] When the control device 10 determines in step S4 that the outside air temperature Tout of the engine room 14 is lower than a predetermined temperature Tt (step S4: NO), the control device 10 proceeds to step S7. In step S7, the control device 10 determines whether the water temperature TW of the cooling water that cools the engine 2 is equal to or higher than a predetermined water temperature TWt. The predetermined water temperature TWt is, for example, 40° C. or higher. When the engine 2 reaches the predetermined water temperature TWt or higher, the power loss due to the oil of the engine 2 is reduced. This makes it impossible to ignore the power loss due to the mechanical clutch 6. For this reason, when the control device 10 determines that the water temperature TW of the cooling water that cools the engine 2 is equal to or higher than the predetermined water temperature TWt (step S7: YES), the control device 10 proceeds to step S5 and executes torque correction control.

[0033] On the other hand, when the control device 10 determines that the temperature TW of the cooling water that cools the engine 2 is lower than the predetermined water temperature TWt (NO in step S7), the control device 10 advances the process to step S6 and prohibits the torque correction control.

[0034] As described above, according to the present disclosure, it is possible to provide an engine control system 1 capable of suppressing variations in output.

[0035] <Other embodiments> Although the embodiment of the present disclosure has been described above, the present disclosure is not limited to the above embodiment, and various modifications are possible without departing from the gist of the invention. In particular, the multiple modifications described in this specification can be arbitrarily combined as necessary.

[0036] For example, in the above embodiment, the engine 2 is described as a diesel engine, but the present disclosure is not limited thereto. The engine 2 may be a gasoline engine. In this case, the amount of air taken into the engine 2 may be changed according to the correction torque in the torque correction control.

[0037] In the above embodiment, the control device 10 acquires the outside air temperature Tout using the outside air temperature sensor 12 disposed in the engine compartment 14, but the present disclosure is not limited to this. The outside air temperature Tout may be acquired using, for example, an intake air temperature sensor capable of acquiring the temperature of intake air, or may be estimated from the water temperature TW. [Explanation of symbols]

[0038] 1: control system, 2: engine, 2a: rotating shaft 4: Fan, 6: Mechanical clutch, 10: Control device, 14: Engine room CON_R: Joint ratio Fan_R: Fan speed Fan_R1: First fan speed Fan_R2: Second fan speed Fan_Rr: Actual fan speed Tout: Outside temperature, Tt: Predetermined temperature

Claims

1. A fan that receives power from the rotating shaft of the engine; a mechanical clutch disposed between the engine and the fan; A control device for controlling the output of the engine; Equipped with the control device acquires a rotation speed of the fan, acquires an engagement ratio of the mechanical clutch from the rotation speed of the fan, acquires a power loss caused by the mechanical clutch according to the engagement ratio, and executes an output correction control to correct an output of the engine according to the power loss. Engine control system.

2. The control device includes: a first fan rotation speed, which is the rotation speed of the fan when the mechanical clutch is in an engaged state, and a second fan rotation speed, which is the rotation speed of the fan when the mechanical clutch is in a disengaged state, are stored; acquiring an actual fan rotation speed, which is an actual rotation speed of the fan, and acquiring the joining ratio based on the actual fan rotation speed, the first fan rotation speed, and the second fan rotation speed; 2. The engine control system of claim 1.

3. The control device prohibits the output correction control while the engine is idling.

2. The engine control system of claim 1.

4. The control device prohibits the output correction control when the engine is in a transient operation.

2. The engine control system of claim 1.

5. The control device prohibits the output correction control during a start mode of the engine.

2. The engine control system of claim 1.

6. The control device acquires an outside air temperature in an engine room in which the engine is housed, and prohibits the output correction control when the outside air temperature is equal to or lower than a predetermined temperature.

6. An engine control system according to any one of claims 1 to 5.

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