Vehicle control device

Abstract

To suppress the abrupt heat generation of a clutch.SOLUTION: A control device of a vehicle is arranged in a power transmission path between a drive source and drive wheels, and comprises a connection / disconnection clutch for releasing the connection between the drive source and the drive wheels by bringing friction fastening to a release state. The control device comprises: a traveling information acquisition part for acquiring the traveling information of the vehicle; a clutch temperature rise speed estimation part for estimating a temperature rise speed of the connection / disconnection clutch on the basis of the traveling information which is acquired by the traveling information acquisition part; and a clutch heat protection part for performing heat protection control to the connection / disconnection clutch when a temperature rise speed estimated by the clutch temperature rise speed estimation part is higher than a preset threshold.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a vehicle control device. [Background technology]

[0002] Conventionally, there is known a vehicle control device equipped with a clutch heat protection means that prevents overheating by controlling the fastening force of a clutch that connects and disconnects transmission between a drive source and drive wheels of a vehicle by frictional fastening (see, for example, Patent Document 1). The vehicle control device disclosed in Patent Document 1 calculates the clutch heat generation amount by multiplying the clutch transmission torque by the clutch rotation speed difference, and transitions to a differential rotation suppression mode when the integrated heat generation amount value exceeds a set value. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2010-190254 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, the vehicle's driving conditions change from moment to moment, and depending on the driving conditions, the calculation of the heat generation integrated value may not keep up, causing a delay in the transition to the differential rotation suppression mode and causing the clutch to heat up suddenly.

[0005] Therefore, an object of the vehicle control device disclosed in this specification is to suppress the sudden heat generation of the clutch. [Means for solving the problem]

[0006] The above object can be achieved by a control device for a vehicle equipped with a disconnecting clutch that is provided in a power transmission path between a drive source and a drive wheel and that disconnects the connection between the drive source and the drive wheel by releasing the frictional engagement, the control device including a driving information acquisition unit that acquires driving information of the vehicle, a clutch temperature rise rate estimation unit that estimates a temperature rise rate of the disconnecting clutch based on the driving information acquired by the driving information acquisition unit, and a clutch thermal protection unit that executes thermal protection control on the disconnecting clutch when the temperature rise rate estimated by the clutch temperature rise rate estimation unit is faster than a predetermined threshold value. Effect of the Invention

[0007] According to the present invention, it is possible to suppress sudden heat generation in the clutch. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram of a hybrid vehicle equipped with a vehicle control device (ECU) according to an embodiment. [Diagram 2] FIG. 2 is a flowchart showing an example of clutch control executed by the ECU. [Diagram 3] FIG. 3 is an example of a map for obtaining an estimated value of the clutch temperature rise rate in the embodiment. [Figure 4] FIG. 4 is an example of a map for obtaining an estimated value of the vehicle weight in the embodiment. [Diagram 5] Figure 5(A) is a graph showing the threshold (21 downline) for shifting down from first to second gear during normal control, and Figure 5(B) is a graph showing the threshold (21 downline) for shifting down from first to second gear during clutch protection control. [Figure 6] FIG. 6 is an example of a map for acquiring the clutch heat generation amount in the embodiment. [Figure 7] FIG. 7 is an example of a map for acquiring the clutch temperature in the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. However, in the drawings, the dimensions, ratios, and the like of each part may not be illustrated to be completely consistent with the actual ones. In addition, some details may be omitted in some drawings. Furthermore, the scale of each element depicted in each drawing may differ from one another.

[0010] [General configuration of hybrid vehicle] FIG. 1 is a schematic diagram of a hybrid vehicle 1. The hybrid vehicle 1 is a four-wheel drive vehicle equipped with front drive wheels 13 and rear drive wheels 32. In the hybrid vehicle 1, a first clutch 14, a first motor generator 15, a second clutch 18, and a transmission 19 are provided in this order in a power transmission path from an engine 10 to the front drive wheels 13. The hybrid vehicle 1 also includes a second motor generator 30 for driving the rear drive wheels 32. Both the engine 10 and the first motor generator 15 are mounted as drive sources for driving the hybrid vehicle 1. The engine 10 is an example of an internal combustion engine. The fuel, number of cylinders, and cylinder arrangement type of the engine 10 are not limited. The engine 10 can use conventionally known fuels such as gasoline, diesel, and alcohol. The engine 10 can use an in-line three-cylinder, in-line four-cylinder, or even a V-type six-cylinder, number of cylinders, and cylinder arrangement type as appropriate.

[0011] The first clutch 14, the first motor generator 15, the second clutch 18, and the transmission 19 are provided inside the transmission unit 11. The transmission unit 11 and the left and right front drive wheels 13 are drivingly connected to each other.

[0012] The first clutch 14 is sometimes referred to as a K0 clutch, and is provided between the engine 10 and the first motor generator 15 on the power transmission path. The first clutch 14 receives a supply of hydraulic pressure from a released state and enters an engaged state, connecting the power transmission between the engine 10 and the first motor generator 15. The first clutch 14 enters a released state in response to a stop in the supply of hydraulic pressure and interrupts the power transmission between the engine 10 and the first motor generator 15. The engaged state is a state in which both engagement elements of the first clutch 14 are connected and the engine 10 and the first motor generator 15 have the same rotation speed. The released state is a state in which both engagement elements of the first clutch 14 are separated.

[0013] The first motor generator 15 is connected to the battery 16 via a first inverter 17. The first motor generator 15 functions as a first motor generator that generates driving force for the vehicle in response to power supply from the battery 16, and also functions as a generator that generates electric power to charge the battery 16 in response to power transmission from the engine 10 and the front drive wheels 13. The electric power exchanged between the first motor generator 15 and the battery 16 is adjusted by the first inverter 17.

[0014] The first inverter 17 is controlled by the ECU 100 described later, and converts the DC voltage from the battery 16 into an AC voltage, or converts the AC voltage from the first motor generator 15 into a DC voltage. In the case of powering operation in which the first motor generator 15 outputs torque, the first inverter 17 converts the DC voltage of the battery 16 into an AC voltage and adjusts the power supplied to the first motor generator 15. In the case of regenerative operation in which the first motor generator 15 generates power, the first inverter 17 converts the AC voltage from the first motor generator 15 into a DC voltage and adjusts the power supplied to the battery 16.

[0015] The second clutch 18 is a wet type multi-plate clutch that is in a released state when no hydraulic pressure is applied. The second clutch 18 is provided in a power transmission path between the engine 10 and the first motor generator 15, which are the drive sources, and the front drive wheels 13. The second clutch 18 corresponds to a disconnecting clutch that disconnects the engine 10 and the first motor generator 15 from the front drive wheels 13 by releasing the frictional engagement. The engaged state of the second clutch 18 is a state in which both engagement elements of the second clutch 18 are connected and the rotation speeds of both the front and rear engagement elements of the second clutch 18 are synchronized. The released state is a state in which both engagement elements of the second clutch 18 are separated.

[0016] The transmission 19 is a stepped automatic transmission that changes the gear ratio in multiple stages by changing the gear stage, but is not limited to this and may be a continuously variable automatic transmission. The transmission 19 is provided between the second clutch 18 and the front drive wheels 13 on the power transmission path.

[0017] The transmission unit 11 is further provided with an oil pump 21 and a hydraulic control mechanism 22. The hydraulic pressure generated by the oil pump 21 is supplied to each of the first clutch 14, the second clutch 18, and the transmission 19 via the hydraulic control mechanism 22. The hydraulic control mechanism 22 is provided with hydraulic circuits for each of the first clutch 14, the second clutch 18, and the transmission 19, and various hydraulic control valves for controlling their operating hydraulic pressures. Note that the oil pump 21 is an electric oil pump, but the hybrid vehicle 1 is provided with a mechanical oil pump (not shown) that is rotationally driven by the output shaft of the engine 10 or the first motor generator 15. The mechanical oil pump supplies hydraulic pressure together with the oil pump 21 or instead of the oil pump 21.

[0018] The second motor generator 30 is an auxiliary drive source for the engine 10 and the first motor generator 15, and drives rear drive wheels 32. The second motor generator 30 is connected to the battery 16 via a second inverter 31. The second motor generator 30 functions as a second motor generator that generates drive force for the vehicle in response to power supplied from the battery 16, and also functions as a generator that generates electric power to charge the battery 16 in response to power transmission from the rear drive wheels 32. The electric power exchanged between the second motor generator 30 and the battery 16 is adjusted by the second inverter 31.

[0019] The second inverter 31 is controlled by an ECU 100, which will be described later, and converts the DC voltage from the battery 16 into an AC voltage, or converts the AC voltage from the second motor generator 30 into a DC voltage. In the case of powering operation in which the second motor generator 30 outputs torque, the second inverter 31 converts the DC voltage of the battery 16 into an AC voltage and adjusts the power supplied to the second motor generator 30. In the case of regenerative operation in which the second motor generator 30 generates power, the second inverter 31 converts the AC voltage from the second motor generator 30 into a DC voltage and adjusts the power supplied to the battery 16.

[0020] The hybrid vehicle 1 is provided with an ECU (Electronic Control Unit) 100 as a control device for the vehicle. The ECU 100 is an electronic control unit including a calculation processing circuit that performs various calculation processes related to the driving control of the vehicle, and a memory that stores control programs and data.

[0021] The ECU 100 controls the operation of the engine 10 and the first motor generator 15. Specifically, the ECU 100 controls the torque and rotation speed of the engine 10 by controlling the throttle opening, ignition timing, and fuel injection amount of the engine 10. The ECU 100 controls the torque and rotation speed of the first motor generator 15 by controlling the first inverter 17 to adjust the amount of electric power exchanged between the first motor generator 15 and the battery 16. The ECU 100 also controls the torque and rotation speed of the second motor generator 30 by controlling the second inverter 31 to adjust the amount of electric power exchanged between the second motor generator 30 and the battery 16. Furthermore, the ECU 100 controls the operation of the first clutch 14, the second clutch 18, and the transmission 19 through the control of the hydraulic control mechanism 22.

[0022] Signals are input to the ECU 100 from a vehicle speed sensor 71, an oil temperature sensor 72, a gradient sensor 73, and an accelerator opening sensor 74. The vehicle speed sensor 71 detects the traveling speed of the hybrid vehicle 1. The acceleration of the hybrid vehicle 1 can be obtained by calculating the change over time in the detected value of the vehicle speed sensor 71. The oil temperature sensor 72 detects the temperature of hydraulic oil supplied to hydraulic control mechanism 22, first clutch 14, second clutch 18, and other parts that are operated by hydraulic pressure. The gradient sensor 73 detects the inclination of the hybrid vehicle 1. The accelerator opening sensor 74 detects the amount of depression of an accelerator (not shown). The detected value of the accelerator opening sensor 74 is used for shift-down control in the transmission 19.

[0023] The ECU 100 also receives signals from a first rotation speed sensor 75 that measures the rotation speed of the input side of the second clutch 18 and a second rotation speed sensor 76 that measures the rotation speed of the output side of the second clutch 18. The difference between the rotation speed measured by the first rotation speed sensor 75 and the rotation speed measured by the second rotation speed sensor 76 is calculated as the differential rotation in the second clutch 18.

[0024] The ECU 100 includes a driving information acquisition unit 101 , a clutch temperature rise rate estimation unit 102 , a clutch heat protection unit 103 , and a clutch temperature calculation unit 104 .

[0025] The travel information acquisition unit 101 acquires information on the travel state of the hybrid vehicle 1, for example, whether the hybrid vehicle 1 is traveling on a flat ground or on a slope. The travel information acquisition unit 101 also acquires information on the weight of the hybrid vehicle 1 traveling. These pieces of information are acquired as factors that may affect the amount of heat generated by the second clutch 18. For example, when the hybrid vehicle 1 travels on a slope and enters an uphill state, the amount of heat generated by the second clutch 18 increases. The detection value of the gradient sensor 73 is included in the travel information and is used to calculate the amount of heat generated by the second clutch 18. Also, when the hybrid vehicle 1 is traveling with luggage loaded or traveling with many passengers, the amount of heat generated by the second clutch 18 increases. For this reason, the weight of the hybrid vehicle 1 is included in the travel information and is used to calculate the amount of heat generated by the second clutch 18. The travel information acquisition unit 101 may be linked to a navigation system provided in the hybrid vehicle 1 to acquire information on the slope of the hybrid vehicle 1. The calculation of the amount of heat generated by the second clutch 18 will be described in detail later.

[0026] The clutch temperature rise rate estimation unit 102 estimates the temperature rise rate of the second clutch 18 based on the driving information acquired by the driving information acquisition unit 101.

[0027] The clutch heat protection unit 103 executes heat protection control for the second clutch when the temperature rise rate estimated by the clutch temperature rise rate estimation unit 102 is faster than a preset threshold value. The contents of the heat protection control will be described in detail later.

[0028] The clutch temperature calculation unit 104 calculates the amount of heat generated by the second clutch 18 by integrating the amount of heat generated by the differential rotation in the second clutch 18 and the driving torque obtained by combining the torque of the engine 10 and the torque of the first motor generator 15.

[0029] Next, an example of control executed by the ECU 100 as a vehicle control device will be described with reference to Figures 2 to 7. Figure 2 is a flowchart showing an example of clutch control executed by the ECU 100. The ECU 100 repeatedly executes the process shown in Figure 2 at regular intervals (e.g., every 10 msec) while the hybrid vehicle 1 is running.

[0030] First, in step S1 , the travel information acquisition unit 101 acquires the vehicle speed measured by the vehicle speed sensor 71 , the oil temperature measured by the oil temperature sensor 72 , and the gradient measured by the gradient sensor 73 .

[0031] In step S2, which is executed following step S1, the clutch heating rate estimation unit 102 acquires a clutch heating rate estimate. The clutch heating rate estimation unit 102 acquires an estimate of the clutch heating rate using a map shown in Fig. 3. Referring to Fig. 3, the greater the gradient of the hybrid vehicle 1, the faster the clutch heating rate. Also, the heavier the hybrid vehicle 1, the faster the clutch heating rate. This is because the heavier the hybrid vehicle 1 is and the greater the gradient of the hybrid vehicle 1, the greater the driving torque transmitted by the second clutch 18, and the more likely the temperature of the second clutch 18 will become high.

[0032] Here, the gradient is a value detected by the gradient sensor 73. The weight of the hybrid vehicle 1 is estimated in the following manner using a map exemplified in FIG. 4. First, the traveling information acquisition unit 101 determines whether the hybrid vehicle 1 is traveling on flat ground from the detection value of the gradient sensor 73, and estimates the weight of the hybrid vehicle 1 when the hybrid vehicle 1 is traveling on flat ground. The traveling information acquisition unit 101 finds a weight that matches the combination of the driving torque when the hybrid vehicle 1 is traveling on flat ground and the acceleration of the hybrid vehicle 1. If the driving torque of the hybrid vehicle 1 is the same, the heavier the weight of the hybrid vehicle 1, the smaller the acceleration. By utilizing this relationship, the weight of the hybrid vehicle 1 can be estimated. The acceleration of the hybrid vehicle 1 can be acquired by calculating the time change of the detection value of the vehicle speed sensor 71.

[0033] In step S3, which is executed following step S2, the clutch heat protection unit 103 determines whether the clutch temperature rise rate estimated in step S2 is slower than a preset threshold value. Here, the threshold value is set as a value at which the temperature of the second clutch 18 has not yet reached a temperature at which protective measures are required, but is predicted to rise rapidly to a temperature at which protective measures are required. This threshold value can be set by simulation or experimentation to match the actual machine. When estimating the clutch temperature rise rate, the detection value of the oil temperature sensor 72 can be taken into consideration. Specifically, when the oil temperature is low, the clutch temperature rise rate can be estimated to be low. This is because when the oil temperature is low, the temperature rise rate of the second clutch 18 becomes slow due to the cooling effect of the hydraulic oil.

[0034] If the clutch heat protection unit 103 determines in step S3 that the temperature rise rate is faster than a preset threshold, the clutch heat protection unit 103 proceeds to step S4. In step S4, the clutch heat protection unit 103 transitions to a clutch protection control mode. Then, the clutch heat protection unit 103 implements a clutch protection measure in step S5. In other words, the clutch heat protection unit 103 implements a preventive protection measure regardless of the temperature of the second clutch 18.

[0035] As a first clutch protection measure, clutch heat protection unit 103 reduces the rotation speeds of engine 10 and first motor generator 15 so as to reduce the differential rotation in second clutch 18. This reduces the differential rotation in second clutch 18, and as a result, the amount of heat generated in second clutch 18 is reduced, thereby protecting second clutch 18.

[0036] As a second clutch protection measure, the clutch heat protection unit 103 shifts the transmission 19 to a lower gear. The transmission 19 is connected to the output shaft of the second clutch 18, and by shifting the transmission 19 to a lower gear, the rotation speed of the output side of the second clutch 18 increases. This reduces the difference between the rotation speed of the input side and the rotation speed of the output side of the second clutch 18, and the differential rotation becomes smaller. As a result, the amount of heat generated in the second clutch 18 decreases, and the second clutch 18 is protected.

[0037] As a third measure of the clutch protection measures, the clutch heat protection unit 103 can change the shift line in the transmission 19. Referring to FIG. 5(A), a shift line (21 down line) from second gear (2nd gear) to first gear (1st gear) when normal control is being executed, that is, when clutch protection control is not being executed, is drawn. The shift line is a threshold for performing so-called kickdown, and is set to shift to a lower gear when the accelerator depression amount becomes equal to or greater than a predetermined amount. During normal control, this shift line is constant regardless of the vehicle speed. In contrast, as shown in FIG. 5(B), during clutch protection control, the shift line is changed so as to make it easier to shift to a lower gear at low speeds. By changing the transmission 19 to a lower gear, the rotation speed of the output side of the second clutch 18 increases. As a result, the differential rotation in the second clutch 18 becomes smaller, the amount of heat generated in the second clutch 18 decreases, and the second clutch 18 is protected.

[0038] As a fourth clutch protection measure, the clutch heat protection unit 103 can change the distribution ratio of the drive torque between the front drive wheels 13 and the rear drive wheels 32. The hybrid vehicle 1 of this embodiment is a four-wheel drive vehicle. Therefore, the drive torque of the second motor generator 30 serving as the auxiliary drive source is increased, and the drive torque of the engine 10 and the first motor generator 15 input to the second clutch 18 is reduced. As a result, the drive torque input to the second clutch 18 is reduced, so the amount of heat generated in the second clutch 18 is reduced, and the second clutch 18 is protected.

[0039] The clutch heat protection unit 103 can appropriately select and adopt these clutch protection measures. That is, the clutch heat protection unit 103 can adopt all the measures, or can adopt a combination of some of the measures. Also, the clutch heat protection unit 103 can adopt one of these clutch protection measures.

[0040] Returning to FIG. 2, when the clutch heat protection unit 103 makes an affirmative determination (Yes determination) in step S3, the process proceeds to step S6. In step S6, the clutch temperature calculation unit 104 acquires a clutch state determination value. Here, the clutch state determination value is the temperature of the second clutch 18 based on the amount of heat generated accumulated during the traveling process of the hybrid vehicle 1. The clutch state determination value is acquired based on the maps illustrated in FIGS. 6 and 7.

[0041] The clutch state determination value is obtained by fitting the differential rotation of second clutch 18 and the driving torque input to second clutch 18 into the map shown in Figure 6 to determine the clutch heat generation amount at that time. The larger the differential rotation and the larger the driving torque, the larger the clutch heat generation amount. The clutch heat generation amount obtained in this manner is accumulated while hybrid vehicle 1 is traveling. Note that the process contents shown in Figure 2 are repeatedly executed at regular intervals as described above, but when second clutch 18 is repeatedly in a disengaged state for multiple times, second clutch 18 is considered to be dissipating heat during that period, and the clutch heat generation amount is subtracted.

[0042] The clutch temperature calculation unit 104 calculates the clutch temperature by applying the calculated clutch heat generation amount to the map shown in Fig. 7. At this time, the clutch temperature calculation unit 104 uses the detection value of the oil temperature acquired by the oil temperature sensor 72. This is because if the oil temperature is low, the temperature of the second clutch 18 will decrease due to the cooling effect of the hydraulic oil.

[0043] In step S7, which is executed following step S6, the clutch heat protection unit 103 determines whether the clutch state determination value (clutch temperature) is lower than a preset threshold value. Here, the threshold value is a value at which it is determined that protection of the second clutch 18 is necessary, and can be set by actual machine adaptation through simulation or experiment. If the clutch heat protection unit 103 makes a negative determination in step S7, it proceeds to steps S4 and S5. The processes of steps S4 and S5 are as described above, so detailed description thereof will be omitted here. On the other hand, if the clutch heat protection unit 103 makes a positive determination in step S7, it proceeds to step S8 and continues normal control.

[0044] According to this embodiment, the clutch temperature rise rate of second clutch 18 is estimated based on the traveling information of hybrid vehicle 1, and based on this estimated value, heat protection control is performed on second clutch 18. This makes it possible to avoid sudden heat generation in second clutch 18.

[0045] In the above embodiment, the hybrid vehicle 1 is controlled by a single ECU 100. However, the present invention is not limited to this. For example, the above-described control may be performed by a plurality of ECUs, such as an engine ECU that controls the engine 10, a motor generator ECU that controls the first motor generator 15 and the second motor generator 30, and a clutch ECU that controls the first clutch 14 and the second clutch 18.

[0046] Furthermore, in the above embodiment, a hybrid vehicle has been described, but the same control as in the above embodiment can also be executed for a vehicle equipped with either an engine or a motor generator.

[0047] Furthermore, in the above embodiment, a four-wheel drive vehicle was described, but even in the case of a front-wheel drive vehicle or a rear-wheel drive vehicle, if the vehicle is equipped with a disconnect clutch between the drive source and the drive wheels, the same control as above can be executed, except for the measure to change the torque distribution between the front and rear drive wheels.

[0048] In other words, a vehicle equipped with a disconnecting clutch between the drive source and the drive wheels can be subject to the same control as in the above embodiment.

[0049] Although the embodiments of the present invention have been described in detail above, the present invention is not limited to such specific embodiments, and various modifications and variations are possible within the scope of the gist of the present invention described in the claims. [Explanation of symbols]

[0050] 1 Hybrid vehicles 10 Engine 11. Gear unit 12 Differential 13 Front drive wheels 14 First clutch 15 First motor generator 16 Battery 17 First inverter 18 Second clutch 21 Oil pump 30 Second motor generator 31 Second inverter 32 Rear drive wheel 71 Vehicle speed sensor 72 Oil temperature sensor 73 Gradient Sensor 74 Accelerator opening sensor 100 ECU 101 Driving information acquisition unit 102 Clutch temperature rise rate estimation unit 103 Clutch heat protection unit 104 Clutch temperature calculation unit

Claims

[Claim 1] A control device for a vehicle including a disconnecting clutch that is provided in a power transmission path between a drive source and a drive wheel and that disconnects a connection between the drive source and the drive wheel by releasing a frictional engagement, The control device includes: A driving information acquisition unit that acquires driving information of the vehicle; A clutch temperature rise rate estimation unit that estimates a temperature rise rate of the disconnecting clutch based on the traveling information acquired by the traveling information acquisition unit; a clutch heat protection unit that executes heat protection control for the disconnecting clutch when the temperature rise rate estimated by the clutch temperature rise rate estimation unit is faster than a preset threshold value; A vehicle control device equipped with the vehicle control device.

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