Clutch control system

Abstract

To reduce useless operation of a clutch while preventing a clutch slip when returning from fuel cut.SOLUTION: A processor of a clutch control system is configured to execute steps of: acquiring engine torque ET; calculating basic transmission torque BT of a clutch on the basis of the engine torque ET; calculating first transmission torque FT of the clutch by restricting a variation amount of the basic transmission torque BT on the basis of a first restriction condition a1; controlling the clutch on the basis of the first transmission torque FT; calculating second transmission torque ST of the clutch by restricting the variation amount of the basic transmission torque BT on the basis of a second restriction condition a2 when returning from fuel cut, wherein the second restriction condition a2 further restricts the variation amount than the first restriction condition a1; and controlling the clutch on the basis of the second transmission torque ST when returning from the fuel cut.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a clutch control system.

Background Art

[0002] In an engine, for example, for the purpose of improving fuel efficiency, fuel injection may be intentionally stopped during driving. This is also referred to as "fuel cut". However, when returning from fuel cut, that is, when fuel injection is restarted after fuel cut, if the torque from the engine and the clutch torque are not balanced, the clutch may slip. Therefore, various techniques for preventing clutch slip when returning from fuel cut have been proposed (see, for example, Patent Documents 1 to 3).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0004] When returning from fuel cut as described above, it is desirable to reduce unnecessary operation of the clutch while preventing clutch slip.

[0005] An object of the present invention is to provide a clutch control system that can reduce unnecessary operation of the clutch while preventing clutch slip when returning from fuel cut.

Means for Solving the Problems

[0006] A clutch control system according to one aspect of the present invention is: A clutch is positioned in the torque transmission path between the engine and the wheels, A control device for controlling the clutch, Equipped with, The control device includes one or more processors and one or more storage media for storing instructions executed by the processors, The aforementioned processor, in accordance with the instruction, To obtain engine torque, The basic transmission torque of the clutch is calculated based on the engine torque. The basic transmission torque is calculated as the absolute value of the engine torque, and when the engine torque increases from a negative value to a positive value, the basic transmission torque is reduced to a predetermined positive torque, and furthermore, the basic transmission torque is maintained at the predetermined positive torque until the engine torque reaches the predetermined positive torque. and, The aforementioned basic transmission torque Based , to calculate the first transmission torque of the clutch. The first transmission torque is calculated by modifying the basic transmission torque such that the first transmission torque approaches the basic transmission torque, and the absolute value of the change in the first transmission torque with respect to time is less than or equal to the absolute value of a predetermined first limit value. and, The clutch is controlled based on the first transmission torque, When the clutch is engaged When the fuel cut-off is restored, the basic transmission torque Based , to calculate the second transmission torque of the clutch, The second transmission torque is calculated by modifying the basic transmission torque so that the second transmission torque approaches the basic transmission torque, and so that the absolute value of the change in the second transmission torque with respect to time is less than or equal to the absolute value of a predetermined second limit, and the absolute value of the second limit is smaller than the absolute value of the first limit. , and When the clutch is engaged When the fuel cut-off is restored, the clutch is controlled based on the second transmission torque, It is configured to execute. [Effects of the Invention]

[0007] According to the present invention, when the system returns from fuel cut-off, it is possible to prevent clutch slippage while reducing unnecessary clutch operation. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a schematic diagram showing a clutch control system according to an embodiment. [Figure 2] Figure 2 is a functional block diagram of the ECU. [Figure 3]FIG. 3 is a graph showing the transition of various parameters when returning from fuel cut by turning on the accelerator. [Figure 4] FIG. 4 is a graph showing the transition of various parameters when returning from fuel cut without turning on the accelerator. [Figure 5] FIG. 5 is a flowchart showing the operation of the clutch control system according to the embodiment.

MODE FOR CARRYING OUT THE INVENTION

[0009] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. Specific dimensions, materials, numerical values, etc. shown in such embodiments are merely examples for easy understanding and do not limit the present invention unless otherwise specified. In the specification and drawings, elements having substantially the same functions and configurations are denoted by the same reference numerals to omit redundant description. Also, elements not directly related to the present invention are not shown.

[0010] FIG. 1 is a schematic diagram showing a clutch control system 100 according to an embodiment of the present invention. The clutch control system 100 may also be simply referred to as a "system" in the present disclosure. The system 100 is applied to a vehicle 500 such as, for example, a HEV (Hybrid Electric Vehicle), a gasoline vehicle, or a diesel vehicle. In the present embodiment, the vehicle 500 is a gasoline vehicle. For example, the vehicle 500 includes an engine 10, a transmission 20, a differential device 30, a plurality of wheels 40, and an ECU (control device) 50. The vehicle 500 may further include various other components.

[0011] In the engine 10, the rotational speed of the crankshaft CS, that is, the rotational speed of the engine 10, is measured by the crank angle sensor Se. The crank angle sensor Se is communicably connected to the ECU 50 and transmits measurement data to the ECU 50.

[0012] Engine 10 includes a fuel injector IN. For example, the injector IN may be provided in the combustion chamber and inject fuel into the combustion chamber (so-called direct injection). In other embodiments, engine 10 may be a premixed engine. The injector IN is communicably connected to the ECU 50. The ECU 50 controls the fuel injection amount from the injector IN.

[0013] Vehicle 500 includes a throttle valve V in an intake pipe 2 connected to engine 10. The throttle valve V adjusts the intake air amount flowing through the intake pipe 2. The throttle valve V is communicably connected to the ECU 50. The ECU 50 adjusts the intake air amount by controlling the opening degree of the throttle valve V.

[0014] Vehicle 500 includes an accelerator pedal AP. The accelerator pedal AP is communicably connected to the ECU 50. For example, the ECU 50 controls the opening degree of the throttle valve V and the fuel injection amount from the injector IN based on the depression amount of the accelerator pedal AP, that is, the accelerator opening degree.

[0015] The engine torque generated in engine 10 is transmitted to wheels 40 through components such as transmission 20 and differential 30.

[0016] Transmission 20 includes a clutch CL. The clutch CL transmits or interrupts the torque from engine 10 to wheels 40. For example, the clutch torque of the clutch CL is adjusted by a hydraulic pressure adjusting device 21. For example, the hydraulic pressure adjusting device 21 includes components such as a pump and a valve. The hydraulic pressure adjusting device 21 is communicably connected to the ECU. The ECU 50 adjusts the clutch torque by controlling the hydraulic pressure adjusting device 21.

[0017] For example, the ECU 50 includes one or more processors 51 such as a CPU, one or more storage media 52 such as ROM and RAM, and one or more connectors 53. The ECU 50 may further have other components. The components of the ECU 50 are communicated with one another by a bus. The storage media 52 store one or more programs executed by the processors 51. The programs include instructions for the processors 51. The operation of the ECU 50 as shown in this disclosure is achieved by the processors 51 executing the instructions stored in the storage media 52. The ECU 50 is communicated with components of the system 100 via the connectors 53.

[0018] In the system 100 described above, fuel injection may be intentionally stopped while driving. This is also referred to as "fuel cut" in this disclosure. Fuel cut may be performed for various purposes. For example, fuel cut may be performed to improve fuel efficiency. For example, fuel efficiency can be improved by stopping fuel injection during deceleration. The purpose of fuel cut is not limited to this and may be for other purposes. However, when returning from fuel cut, that is, when fuel injection is resumed after fuel cut, if the engine torque and clutch torque are not balanced, the clutch CL may slip. In this embodiment, system 100 prevents clutch slip by adjusting the clutch torque when returning from fuel cut.

[0019] Figure 2 is a functional block diagram of the ECU 50. The processor 51 functions as an engine torque acquisition unit 54, a first calculation unit 55, a second calculation unit 56, a third calculation unit 57, and a clutch control unit 58, according to instructions stored in the storage medium 52.

[0020] When functioning as an engine torque acquisition unit 54, the processor 51 estimates the torque transmitted from the crankshaft CS to the multiple wheels 40, i.e., the engine torque ET, based on one or more parameters of the engine 10. For example, the processor 51 may estimate the engine torque ET based on at least one of the engine speed of the engine 10 received from the crank angle sensor Se, the opening of the throttle valve V, the amount of fuel injected from the injector IN, and combinations thereof. The estimation of the engine torque ET may be carried out based on known methods.

[0021] When functioning as the first calculation unit 55, the processor 51 calculates the basic transmission torque BT of the clutch CL based on the engine torque ET obtained in the engine torque acquisition unit 54. The calculation of the basic transmission torque BT will be described in detail below.

[0022] When functioning as a second calculation unit 56, the processor 51 calculates a first transmission torque FT based on the basic transmission torque BT obtained in the first calculation unit 55 in order to modify it to suit actual use. The calculation of the first transmission torque FT will also be described in detail below.

[0023] When functioning as a third calculation unit 57, the processor 51 calculates a second transmission torque ST based on the basic transmission torque BT obtained in the first calculation unit 55 in order to modify it to suit use when recovering from fuel cut-off. The calculation of the second transmission torque ST will also be described in detail below.

[0024] When functioning as a clutch control unit 58, the processor 51 controls the clutch CL during the operation of the vehicle 500, basically based on a first transmission torque FT calculated by a second calculation unit 56. Also, when the fuel cut is restored, the processor 51 controls the clutch CL based on a second transmission torque ST calculated by a third calculation unit 57.

[0025] Figure 3 is a graph showing the changes in various parameters when the fuel cut-off is restored by pressing the accelerator. Figure 4 is a graph showing the changes in various parameters when the fuel cut-off is restored without pressing the accelerator. In all graphs in Figures 3 and 4, the horizontal axis represents time.

[0026] In the graphs (a) of Figures 3 and 4, the vertical axis represents the accelerator pedal opening, i.e., the amount the accelerator pedal AP is pressed.

[0027] In the graphs (b) of Figures 3 and 4, the vertical axis represents the fuel cut flag. When the fuel cut flag is zero, fuel is injected from the injector 17. When the fuel cut flag is 1, fuel cut is performed, meaning that fuel injection from the injector 17 is stopped.

[0028] In graph (c) of Figures 3 and 4, the vertical axis represents torque. In graph (c), the dashed line represents engine torque ET, and the solid line represents basic transmission torque BT.

[0029] In graph (d) of Figures 3 and 4, the vertical axis represents torque. In graph (d), the dashed line represents the first transmission torque FT, and the solid line represents the second transmission torque ST.

[0030] Referring to graph (a) in Figure 3, in this example, the accelerator opening is zero before time t1, and increases at time t1. In this case, for example, vehicle 500 decelerates until time t1 and then accelerates from time t1 onwards.

[0031] Referring to graph (b), before time t1, the fuel cut flag is 1, meaning that fuel cut is being performed. Therefore, no fuel is injected from injector 17. In this case, engine 10 is rotated not by the combustion of fuel, but by the torque from wheels 40. Therefore, as shown in graph (c), the engine torque ET is negative before time t1.

[0032] The basic transmission torque BT of the clutch CL is determined to balance the engine torque ET in order to prevent clutch slippage. For example, the basic transmission torque BT is calculated as the absolute value of the engine torque ET, i.e., a positive value. This ensures that the engine torque ET and the clutch torque are balanced.

[0033] Referring to graph (d), the first transmission torque FT is calculated based on the basic transmission torque BT to match the actual use of the clutch CL during the operation of the vehicle 500. Specifically, as detailed below, the first transmission torque FT is calculated by limiting the amount of change in the basic transmission torque BT based on a predetermined first limiting condition in order to suppress abrupt changes in clutch torque. However, before time t1, the basic transmission torque BT in graph (c) is constant. Therefore, as shown in graph (d), before time t1, the first transmission torque FT may be the same as the basic transmission torque BT.

[0034] Furthermore, before time t1, fuel cut is being performed, meaning the system is not recovering from fuel cut. For this reason, the second transmission torque ST does not need to be calculated before time t1. Before time t1, the processor 51 controls the clutch CL based on the first transmission torque FT.

[0035] Returning to graph (a), as the accelerator opening increases at time t1, i.e., when the accelerator pedal AP is pressed, the fuel cut flag switches to 0, as shown in graph (b). Therefore, fuel is injected from injector 17, and engine 10 begins to rotate due to the combustion of fuel. Thus, referring to graph (c), the engine torque ET increases towards a positive value from time t1. However, since the engine torque ET crosses zero, the absolute value of the engine torque ET decreases. In this case, if the basic transmission torque BT is directly calculated as the absolute value of the engine torque ET, the basic transmission torque BT will drop to zero despite the accelerator pedal AP being pressed. However, since the engine torque ET increases immediately, dropping the basic transmission torque BT to zero would require unnecessary operation of the clutch CL. Therefore, the basic transmission torque BT is maintained at torque Tr1 until the engine torque ET reaches a predetermined positive torque Tr1. In this example, the engine torque ET reaches torque Tr1 at time t2. Therefore, the basic transmission torque BT is maintained at torque Tr1 from time t1 to time t2. Torque Tr1 may be determined based on various factors, such as the specifications of vehicle 500. After the engine torque ET reaches torque Tr1 at time t2, the basic transmission torque BT is again calculated as the absolute value of the engine torque ET.

[0036] Referring to graph (d), as described above, the first transmission torque FT is calculated by limiting the change in the basic transmission torque BT based on a predetermined first limit condition in order to suppress abrupt changes in clutch torque. For example, referring to graph (c), the basic transmission torque BT decreases abruptly to torque Tr1 at time t1. If the basic transmission torque BT changes abruptly, and the basic transmission torque BT is used directly to control the clutch torque, the clutch CL may not be able to follow the basic transmission torque BT. Therefore, the first transmission torque FT is calculated by limiting the change in the basic transmission torque BT based on a predetermined first limit condition in order to suppress abrupt changes. For example, the first limit condition may be a1, which is the limit value of the slope a (i.e., a = ΔTr / Δt) in the graph of torque Tr with respect to time t, as shown in graph (d). In this case, the first transmission torque FT is calculated by modifying the basic transmission torque BT so that the absolute value of the slope a is less than or equal to the absolute value of the first limit value a1. Once the first transmission torque FT decreases to torque Tr1, it is maintained at torque Tr1. Furthermore, the first transmitted torque FT increases after the engine torque ET reaches torque Tr1 at time t2. Unlike the second limit value a2, which will be detailed below, the first limit value a1 is used throughout the operation of the vehicle 500. For example, the first limit value a1 may be determined based on various factors such as the specifications of the vehicle 500. Note that the first limit condition is not limited to the limit value a1 of slope a as described above, but may be any other limit condition.

[0037] The second transmission torque ST is calculated based on the basic transmission torque BT in graph (c) so that the basic transmission torque BT is suitable for use when recovering from fuel cut. As described above, when recovering from fuel cut, the engine torque ET crosses zero, so the absolute value of the engine torque ET decreases. However, the engine torque ET increases immediately. Therefore, increasing the clutch torque after reducing it to torque Tr1, as with the first transmission torque FT, can lead to unnecessary operation of the clutch CL. Thus, in this embodiment, the second transmission torque ST is calculated by further limiting the amount of change in the basic transmission torque BT based on a second limiting condition. The second limiting condition limits the amount of change in the basic transmission torque BT even more than the first limiting condition. In this embodiment, the second limiting condition is the limit value a2 of slope a. When the first and second limiting conditions are the limit values ​​a1 and a2 of slope a, the absolute value of the second limit value a2 is smaller than the absolute value of the first limit value a1. The second transmission torque ST is calculated by modifying the basic transmission torque BT so that the absolute value of the slope a is less than or equal to the absolute value of the second limit value a2. This configuration prevents clutch slip while eliminating unnecessary operation of the clutch CL. For example, the second limit value a2 may be determined based on various factors such as the specifications of the vehicle 500. Note that the second limit condition is not limited to the limit value a2 of the slope a as described above, but may be any other limit condition.

[0038] The processor 51 controls the clutch CL based on the second transmission torque ST during the period from time t1 until time t3 when the first transmission torque FT increases to or above the second transmission torque ST.

[0039] Next, when the first transmission torque FT increases to or above the second transmission torque ST at time t3, the processor 51 controls the clutch CL again based on the first transmission torque FT. After time t3, the second transmission torque ST does not need to be calculated.

[0040] Referring to graph (a) in Figure 4, in this example, the accelerator opening is maintained at zero. In this case, for example, vehicle 500 maintains deceleration. However, if the engine speed of 10 drops too low, the fuel cut flag is switched from 1 to 0, as shown in graph (b), to prevent stalling, and fuel injection is resumed without the accelerator being pressed.

[0041] Referring to graph (b), before time t4, the fuel cut flag is 1, meaning that fuel cut is performed. Therefore, no fuel is injected from injector 17. Thus, as shown in graph (c), the engine torque ET is a negative value before time t4, similar to the example in Figure 3. The basic transmission torque BT is calculated as the absolute value of the engine torque ET. As shown in graph (d), before time t4, the first transmission torque FT may be the same as the basic transmission torque BT. Also, before time t4, the second transmission torque ST does not need to be calculated. Before time t4, the processor 51 controls the clutch CL based on the first transmission torque FT.

[0042] Returning to graph (b), as shown above, the fuel cut flag switches from 1 to 0 at time t4. Therefore, fuel is injected from injector 17, and engine 10 starts to rotate due to fuel combustion. Thus, referring to graph (c), the engine torque ET increases towards a positive value from time t4. Similar to the example in Figure 3, the basic transmission torque BT is maintained at torque Tr1 until the engine torque ET reaches a predetermined positive torque Tr1 at time t5. After the engine torque ET reaches torque Tr1 at time t5, the basic transmission torque BT is calculated as the absolute value of the engine torque ET.

[0043] Referring to graph (d), the first transmission torque FT is calculated by modifying the basic transmission torque BT so that the absolute value of the slope a is less than or equal to the absolute value of the first limit a1, similar to the example in Figure 3. Once the first transmission torque FT decreases to torque Tr1, it is maintained at torque Tr1. Furthermore, the first transmission torque FT increases after the engine torque ET reaches torque Tr1 at time t5. The second transmission torque ST is calculated by modifying the basic transmission torque BT so that the absolute value of the slope a is less than or equal to the second limit a2, similar to the example in Figure 3.

[0044] In the example in Figure 4, fuel injection is restarted without pressing the accelerator, as described above. In this case, the increase in engine torque ET in graph (c) is slower than in the example in Figure 3. Consequently, the increase in the first transmission torque FT in graph (d) is also slower. In this embodiment, the processor 51 calculates the second transmission torque ST by limiting the change in the basic transmission torque BT based on the first limiting condition if the first transmission torque FT does not increase to or above the second transmission torque ST during a predetermined period TP from time t4 when fuel injection is restarted. That is, after the predetermined period TP has elapsed from time t4, the second transmission torque ST is calculated by modifying the basic transmission torque BT so that the absolute value of the slope a is less than or equal to the first limiting value a1. This configuration prevents unnecessary restriction of the change in clutch torque. For example, the predetermined period TP may be determined based on various factors such as the specifications of the vehicle 500.

[0045] The processor 51 controls the clutch CL based on the second transmission torque ST during the period from time t4 until time t6 when the first transmission torque FT increases to or above the second transmission torque ST.

[0046] Next, when the first transmission torque FT increases to or above the second transmission torque ST at time t6, the processor 51 controls the clutch CL again based on the first transmission torque FT. After time t6, the second transmission torque ST does not need to be calculated.

[0047] Next, we will explain the operation of system 100.

[0048] Figure 5 is a flowchart showing the operation of the clutch control system 100 according to the embodiment. For example, the operation shown in Figure 5 may start when the fuel cut flag is set to 1, that is, when fuel cut is initiated. In addition to the operation shown in Figure 5, the processor 51 acquires the engine torque ET throughout the driving of the vehicle 500, calculates the basic transmission torque BT and the first transmission torque FT, and controls the clutch CL based on the first transmission torque FT.

[0049] The processor 51 determines whether fuel injection has been restarted (step S100). For example, the processor 51 determines whether the fuel cut flag has been switched from 1 to 0. If it is determined in step S100 that fuel injection has not been restarted (NO), the processor 51 repeats step S100 at a predetermined interval.

[0050] In step S100, if it is determined that fuel injection has been restarted (YES), the processor 51 determines whether a predetermined period TP has elapsed since the restart of fuel injection (step S102).

[0051] In step S102, if it is determined that the period TP has not elapsed (NO), the processor 51 calculates the second transmission torque ST based on the second limit value a2 (step S104).

[0052] In step S102, if it is determined that the period TP has elapsed (YES), the processor 51 calculates the second transmission torque ST based on the first limit value a1 (step S106).

[0053] Next, the processor 51 determines whether the first transmission torque FT has increased to or greater than the second transmission torque ST (step S108). If it is determined in step S108 that the first transmission torque FT has increased to or greater than the second transmission torque ST (YES), the processor 51 controls the clutch CL based on the first transmission torque FT (step S110) and terminates the series of operations. From this point onward, the processor 51 controls the clutch CL based on the first transmission torque FT.

[0054] In step S108, if it is determined that the first transmission torque FT has not increased to or greater than the second transmission torque ST (NO), the processor 51 controls the clutch CL based on the second transmission torque ST (step S112), and steps S102 to S112 are repeated.

[0055] The system 100 described above includes a clutch CL positioned in the torque transmission path between the engine 10 and the wheels 40, and an ECU 50 that controls the clutch CL. The ECU 50 includes one or more processors 51 and one or more storage media 52 that store instructions executed by the processors 51. The processor 51 is configured to perform the following according to the instructions: acquire engine torque ET; calculate a basic transmission torque BT of the clutch CL based on the engine torque ET; calculate a first transmission torque FT of the clutch CL by limiting the amount of change of the basic transmission torque BT based on a first limiting condition a1; control the clutch CL based on the first transmission torque FT; and, upon recovery from fuel cut, calculate a second transmission torque ST of the clutch CL by limiting the amount of change of the basic transmission torque BT based on a second limiting condition a2, wherein the second limiting condition a2 further limits the amount of change than the first limiting condition a1; and control the clutch CL based on the second transmission torque ST upon recovery from fuel cut. With this configuration, as described above, when the fuel cut is restored, clutch slippage can be prevented while reducing unnecessary operation of the clutch CL.

[0056] Furthermore, in system 100, the processor 51 is further configured to, in accordance with instructions, control the clutch CL based on the first transmission torque FT when the first transmission torque FT increases to or greater than the second transmission torque ST upon recovery from fuel cut. Such a configuration prevents unnecessarily limiting the amount of change in clutch torque.

[0057] Furthermore, in system 100, the processor 51 is further configured to calculate the second transmission torque ST of the clutch CL by limiting the amount of change in the basic transmission torque BT based on a first limiting condition when a predetermined period TP has elapsed since the restart of fuel injection, in accordance with an instruction. With such a configuration, it is possible to prevent unnecessarily limiting the amount of change in the clutch torque.

[0058] Although embodiments have been described above with reference to the attached drawings, the present invention is not limited to these embodiments. It will be clear to those skilled in the art that various modifications or alterations can be conceived within the scope of the claims, and these will naturally also fall within the technical scope of the present invention. Furthermore, the steps of the ECU 50 in the above embodiments do not have to be performed in the order described above, and may be performed in a different order as long as no technical inconsistency arises.

[0059] For example, in the above embodiment, the system 100 controls the clutch CL in the transmission 20. In other embodiments, the system 100 may control any clutch located in the torque transmission path between the engine 10 and the wheels 40, for example, a clutch in a torque converter, in the same manner as above.

[0060] Furthermore, the above embodiment described an example of when the vehicle 500 recovers from a fuel cut-off during deceleration. However, the above control of the clutch CL can also be used in various other situations in which the vehicle 500 recovers from a fuel cut-off. For example, in another embodiment in which the vehicle 500 is an HEV, the vehicle 500 may also recover from a fuel cut-off when the power source is switched from the motor to the engine. In this case as well, the system 100 may control the clutch CL in the same manner as described above. [Explanation of Symbols]

[0061] 10 Engines 40 wheels 51 processors 52 Storage medium 100 Clutch Control System a1 First restriction a2 Second restriction BT Basic Transmission Torque CL Clutch ET Engine Torque FT 1st transmission torque ST 2nd transmission torque

Claims

1. A clutch is positioned in the torque transmission path between the engine and the wheels, A control device for controlling the clutch, Equipped with, The control device includes one or more processors and one or more storage media for storing instructions executed by the processors. The aforementioned processor, in accordance with the instruction, To obtain engine torque, The basic transmission torque of the clutch is calculated based on the engine torque, wherein the basic transmission torque is calculated as the absolute value of the engine torque, and when the engine torque increases from a negative value to a positive value, the basic transmission torque is reduced to a predetermined positive torque, and furthermore, the basic transmission torque is maintained at the predetermined positive torque until the engine torque reaches the predetermined positive torque. The first transmission torque of the clutch is calculated based on the basic transmission torque, wherein the first transmission torque is calculated by modifying the basic transmission torque so that the first transmission torque approaches the basic transmission torque, and the absolute value of the change in the first transmission torque with respect to time is less than or equal to the absolute value of a predetermined first limit value. The clutch is controlled based on the first transmission torque, When the clutch is engaged and the fuel cut-off is restored, the second transmission torque of the clutch is calculated based on the basic transmission torque, wherein the second transmission torque is calculated by modifying the basic transmission torque so that the second transmission torque approaches the basic transmission torque, and the absolute value of the change in the second transmission torque with respect to time is less than or equal to the absolute value of a predetermined second limit value, and the absolute value of the second limit value is smaller than the absolute value of the first limit value. When the clutch is engaged and the fuel cut-off is restored, the clutch is controlled based on the second transmission torque. Configured to perform, Clutch control system.

2. The aforementioned processor, in accordance with the instruction, When the clutch is controlled based on the second transmission torque, if the first transmission torque increases to or greater than the second transmission torque, the clutch is controlled based on the first transmission torque. Further configured to perform, The clutch control system according to claim 1.

3. The aforementioned processor, in accordance with the instruction, When a predetermined period has elapsed since the restart of fuel injection, the second transmission torque of the clutch is calculated by modifying the basic transmission torque so that the second transmission torque approaches the basic transmission torque, and the absolute value of the change in the second transmission torque with respect to time is less than or equal to the absolute value of the first limit value. Further configured to perform, The clutch control system according to claim 1.

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