Vehicle control device

Abstract

Provided is a vehicle control device capable of suppressing the occurrence of sound and shock when engaging an engaged clutch. When switching from a driving state in which only one wheel is driven to an all-wheel driving state is determined, the rotational speed of the electric motor is increased so as to synchronize the rotational speeds of the opposing teeth of the clutch. When it is determined that the rotational speeds of the opposing meshing teeth are synchronized, switching to the engaged state of the clutch is started. The rotational speed of the meshing teeth on the other wheel side after a predetermined time from the synchronization determination time point to the meshing start time point is calculated on the basis of the acceleration / deceleration request. The rotational speed of the motor is changed such that the rotational speed of the motor-side meshing teeth becomes the rotational speed of the wheel-side meshing teeth after a predetermined time. In a transition from the synchronization determination time point to the engagement start time point, the rotational speed of the motor is corrected such that the opposing engagement teeth are engaged with each other in a state in which the rotational speeds are synchronized.

Description

Technical Field

[0001] The present invention relates to a vehicle control device in which, when only one of the front and rear wheels is driven, the engaging clutch located in the power transmission path between the other of the front and rear wheels and the electric motor is disengaged. Background Technology

[0002] Vehicle control devices are widely known, comprising a power source that drives only one of the front and rear wheels, an electric motor that drives only the other of the front and rear wheels, and an engaging clutch disposed in the power transmission path between the other wheel and the electric motor. For example, a front-and-rear-wheel drive vehicle described in Patent Document 1 corresponds to this. In Patent Document 1, the engaging clutch is engaged after controlling the electric motor in such a way that the rotational speed of the electric motor, inferred from the current and duty cycle of the electric motor, matches the rotational speed corresponding to the speed of the other wheel detected by a sensor.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2001-1779 Summary of the Invention

[0006] However, from the moment the rotational speeds of the opposing meshing teeth of the clutch are determined to be synchronized until the switch to the clutch engagement state begins and the opposing meshing teeth actually begin to engage, a certain amount of time is required. Therefore, with the increase in acceleration and deceleration, during the transition from a driving state that only drives one wheel to an all-wheel drive state where the clutch is engaged, the rotational speed of the other wheel-side meshing teeth of the clutch's opposing meshing teeth changes due to acceleration and deceleration. Consequently, the difference in rotational speed at the start of engagement of the opposing meshing teeth of the clutch is inconsistent with the synchronization determination time, and there is a possibility that the opposing meshing teeth will engage each other while their rotational speeds are not synchronized, resulting in increased noise and impact.

[0007] The present invention was made against the background of the above circumstances, and its object is to provide a vehicle control device that can suppress noise and impact when engaging a meshing clutch.

[0008] The essence of the first invention is that (a) a vehicle control device, the vehicle having a power source that drives only one of the front wheels and the rear wheels, an electric motor that drives only the other of the front wheels and the rear wheels, and an engaging clutch disposed in the power transmission path between the other wheel and the electric motor, wherein (b) when it is determined that a switch is being made from a driving state in which only one of the wheels is driven when the clutch is disengaged to an all-wheel drive state in which the front wheels and the rear wheels are driven when the clutch is engaged, the electric motor is synchronized with the rotational speed of the relative meshing teeth of the clutch. (c) When the rotational speed of the motor increases, if it is determined that the rotational speeds of the opposing meshing teeth are synchronized, a switch to the engagement state of the clutch is initiated, and, based on the acceleration and deceleration requirements of the vehicle, the rotational speed of the wheel-side meshing teeth of the other of the opposing meshing teeth is calculated after a predetermined time from the time point at which the synchronization is determined to be completed to the time point at which the engagement of the opposing meshing teeth begins, so that the rotational speed of the motor-side meshing teeth of the opposing meshing teeth becomes the rotational speed of the wheel-side meshing teeth after the predetermined time, thereby changing the rotational speed of the motor.

[0009] According to the first invention, when a switch from a drive state that drives only one wheel to an all-wheel drive state is determined, the rotational speed of the motor is increased to synchronize the rotational speeds of the opposing meshing teeth of the clutch. When the rotational speeds of the opposing meshing teeth are determined to be synchronized, a switch to clutch engagement begins. Furthermore, the rotational speed of the meshing teeth on the other wheel side is calculated based on acceleration and deceleration requirements, after a predetermined time from the synchronization determination time point to the engagement start time point. Then, the rotational speed of the motor is changed so that the rotational speed of the meshing teeth on the motor side becomes the rotational speed of the meshing teeth on the wheel side after the predetermined time. Thus, during the transition from the synchronization determination time point to the engagement start time point of the opposing meshing teeth, the rotational speed of the motor is corrected by engaging the opposing meshing teeth while maintaining synchronized rotational speeds. Therefore, when engaging the meshing clutch, noise and impact can be suppressed. Attached Figure Description

[0010] Figure 1 This is a diagram illustrating the general structure of a vehicle to which the present invention is applied.

[0011] Figure 2 It is a diagram illustrating the control functions and main components of the control system in a vehicle.

[0012] Figure 3This is a flowchart illustrating the main control actions of the electronic control device, and a flowchart illustrating the control actions used to suppress noise and impact when the claw clutch is engaged. Detailed Implementation

[0013] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0014]

Example

[0015] Figure 1 This is a diagram illustrating the schematic structure of the vehicle 10 to which the present invention is applied. Figure 1 In this vehicle 10, left and right front wheels 12, front drive units 20 driving the front wheels 12, left and right rear wheels 14, and rear drive units 30 driving the rear wheels 14 are spaced apart from each other. Additionally, the vehicle 10 includes a battery 40 as a rechargeable DC power source. Furthermore, the term "left and right" refers to left and right relative to the vehicle 10's direction of travel.

[0016] Vehicle 10 is an all-wheel drive vehicle with adjustable drive torque distribution ratio between the front wheels 12 and the rear wheels 14. All-wheel drive (AWD) and four-wheel drive (4WD) mean the same thing. In addition to driving under 4WD control (the same meaning applies to 4WD mode), vehicle 10 can also achieve two-wheel drive (2WD) control (the same meaning applies to 2WD mode), where drive torque is distributed only to either the front wheels 12 or the rear wheels 14.

[0017] The front drive unit 20 includes an MGF 22, a front power transmission unit 24, a front PCU (Power Control Unit) 26, and a front housing 28. The front housing 28 is a housing mounted on the vehicle body.

[0018] MGF22 is housed within the front housing 28. MGF22 is a known rotating electromechanical device, a so-called electric generator, connected to the battery 40 via the front PCU 26. MGF22 is a front electric motor that serves as the power source for driving only the front wheel 12, which is one of the front wheel 12 and the rear wheel 14.

[0019] The front PCU26 is, for example, a power control device that includes an inverter and controls the power exchanged between the battery 40 and the MGF22. The front PCU26 is controlled by the electronic control device 80 described later, which controls the MGF torque Tmgf, which is the torque of the MGF22.

[0020] The front power transmission device 24 includes a counter gear mechanism 50, a countershaft 52, an end-drive gear 54, and a front differential gear 56 within the front housing 28. Additionally, the front power transmission device 24 includes left and right front drive shafts 58 connected to the front differential gear 56. The counter gear mechanism 50 is a gear pair consisting of a drive gear 50a and a driven gear 50b meshing with the drive gear 50a. The drive gear 50a is connected to the MGF22, and the driven gear 50b is connected to the end-drive gear 54 via the countershaft 52. The end-drive gear 54 meshes with the differential gear 56r of the front differential gear 56. The front drive shafts 58 connect the front differential gear 56 and the front wheels 12. The front power transmission device 24 transmits power from the MGF22 to the front wheels 12.

[0021] The rear drive unit 30 includes an MGR 32, a rear power transmission unit 34, a rear PCU 36, and a rear housing 38. The rear housing 38 is a housing mounted on the vehicle body.

[0022] MGR32 is located within the rear housing 38. MGR32 is a known rotating electromechanical device, a so-called electric generator, connected to the battery 40 via the rear PCU 36. MGR32 is a rear electric motor that drives only the rear wheel 14, which is the other wheel among the front wheel 12 and the rear wheel 14.

[0023] The rear PCU36 has the same function as the front PCU26, and is controlled by the electronic control device 80 described later, which controls the MGR torque Tmgr, which is the torque of MGR32.

[0024] The rear power transmission device 34 includes a secondary gear mechanism 60, a secondary shaft 62, an end-drive gear 64, a rear differential gear 66, and left and right rear drive shafts 68. The rear power transmission device 34 has the same function as the front power transmission device 24, transmitting power from the MGR 32 to the rear wheels 14.

[0025] The rear power transmission device 34 includes a claw clutch 70 and an actuator 72. The claw clutch 70 is a known engaging clutch located in the power transmission path between the rear wheel 14 and the MGR32. The actuator 72 controls the switching between the engagement and disengagement states of the claw clutch 70 by means of an electronic control device 80 described later.

[0026] A claw clutch 70 is provided, for example, in the power transmission path between the rear differential gear 66 and the left rear wheel 14. The claw clutch 70 has a first claw tooth 70a and a second claw tooth 70b as opposing meshing teeth. The first claw tooth 70a is connected to the rear differential gear 66 and is the meshing tooth on the MGR32 side of the opposing meshing teeth. The second claw tooth 70b is connected to the left rear drive shaft 68 and is the meshing tooth on the rear wheel 14 side of the opposing meshing teeth. The claw clutch 70 is engaged by the mutual meshing of the first claw tooth 70a and the second claw tooth 70b, and disengaged by disengaging them.

[0027] In vehicle 10, the front wheels 12 are driven in both 2WD and 4WD modes, while the rear wheels 14 are driven only in 4WD mode. In 4WD mode, the front wheels 12 and rear wheels 14 are driven when the claw clutch 70 is engaged, and the power transmission path between the rear wheels 14 and the MGR 32 is connected. In 2WD mode, only the front wheels 12 are driven when the claw clutch 70 is disengaged, and the power transmission path between the rear wheels 14 and the MGR 32 is disconnected. By disengaging in 2WD control, the rotation of the rotating components of the rear power transmission device 34 (closer to the MGR 32 side than the claw clutch 70) and the rotation of the MGR 32 are stopped. This prevents or suppresses churning losses caused by the oil sealed in the rear housing 38 being stirred by the secondary gear mechanism 60, the end drive gear 64, the rear differential gear 66, etc. The claw clutch 70 is a disconnecting mechanism that can cut off the power transmission path between the rear wheels 14 and the MGR 32.

[0028] Figure 2 This diagram illustrates the control functions and main components of the control system in vehicle 10. Figure 2 In addition, vehicle 10 also includes an electronic control unit 80, which serves as a controller for the vehicle 10 (see reference). Figure 1 (The "ECU" in the text). The electronic control unit 80 is configured, for example, as a so-called microcomputer including a CPU, RAM, ROM, input / output interfaces, etc. The electronic control unit 80 includes, for example, MGECU82, BEVECU84, VSCECU86, DCSECU88, etc.

[0029] The electronic control unit 80 is supplied with various signals based on detection values ​​obtained from various sensors installed on the vehicle 10. These sensors include, for example, the MGR rotation sensor 90, wheel speed sensor 92, accelerator opening sensor 94, and brake sensor 96. The signals include, for example, the MGR rotation speed Nmgr (as the rotation speed of the MGR 32), the left rear wheel rotation speed Nwrl, the accelerator opening θacc, and the brake operation amount Bra.

[0030] The electronic control unit 80 outputs various command signals to various devices installed in the vehicle 10. These devices include, for example, the rear PCU 36 and the actuator 72. Examples of these command signals include, for instance, the MGR torque indication value used to control the MGR 32, and the actuator control indication value used to control the switching between the engagement and disengagement states of the claw clutch 70.

[0031] BEVECU84 calculates the required acceleration for vehicle 10 based on accelerator opening θacc, etc. BEVECU84 calculates the required deceleration for vehicle 10 based on accelerator opening θacc and / or brake operation amount Bra, etc.

[0032] The BEVECU84 determines the switching of drive states based on factors such as required acceleration, required deceleration, wheel slippage, and driving mode selection executed by the driver. For example, if the BEVECU84 requires increased acceleration or deceleration in 2WD control, it determines a switch to 4WD mode and outputs a command to synchronize the rotational speeds of the opposing meshing teeth of the claw clutch 70 to the MGECU82. The MGECU82, following the command to synchronize the rotational speeds of the opposing meshing teeth of the claw clutch 70, increases the MGR rotational speed Nmgr by making the rotational speed of the first claw tooth 70a equal to the rotational speed of the left rear wheel Nwrl, which is equivalent to the rotational speed of the second claw tooth 70b. Thus, when the electronic control unit 80 determines a switch from 2WD to 4WD mode, it increases the MGR rotational speed Nmgr by synchronizing the rotational speeds of the opposing meshing teeth of the claw clutch 70.

[0033] When the BEVECU84 determines that the rotational speeds of the opposing meshing teeth of the claw clutch 70 are synchronized, it outputs a command to switch the claw clutch 70 to the engaged state to the DCSECU88. The first claw tooth 70a is connected to the MGR32 via the secondary gear mechanism 60, the end drive gear 64, etc., so the rotational speed of the first claw tooth 70a and the MGR rotational speed Nmgr are interchangeable. The BEVECU84 determines whether the rotational speeds of the opposing meshing teeth of the claw clutch 70 are synchronized based on whether the absolute value of the difference between the left rear wheel rotational speed Nwrl and the MGR rotational speed Nmgr is less than a predetermined rotational difference. The predetermined rotational difference is, for example, a pre-determined threshold used to determine whether the rotational speeds of the opposing meshing teeth of the claw clutch 70 are synchronized. The DCSECU88 actuates the actuator 72 in a manner that makes the claw clutch 70 engaged, according to the command to switch the claw clutch 70 to the engaged state. In this way, when the electronic control device 80 determines that the rotational speeds of the relative meshing teeth of the claw clutch 70 are synchronized, it begins to switch to the engagement state of the claw clutch 70.

[0034] However, from the moment the rotational speeds of the relative meshing teeth of the claw clutch 70 are synchronized until the switching to the engaged state of the claw clutch 70 and the actual engagement of the first claw tooth 70a and the second claw tooth 70b, a certain amount of time is required. Therefore, there is a possibility that the noise and impact may increase due to a deviation from synchronization when the first claw tooth 70a and the second claw tooth 70b are actually engaged. This phenomenon is significant because of the rotational change of the rear wheel 14 when transitioning from 2WD to 4WD mode when large acceleration or deceleration is required in 2WD mode. Furthermore, while it is possible to suppress noise and impact by employing a mechanical synchronization mechanism in the claw clutch 70, this results in a larger system size and increased cost.

[0035] If reference Figure 2 The time required to switch the claw clutch 70 to the engaged state is, for example, the time from the input of the left rear wheel rotation speed Nwrl signal from the wheel speed sensor 92 (see [1]-1) to the speed calculated by the VSCECU 86 (see [2]). Additionally, it is the time from the input of the MGR rotation speed Nmgr signal from the MGR rotation sensor 90 (see [1]-2) to the speed calculated by the MGECU 82 (see [3]). Furthermore, it is the time to send the calculated speed result to the BEVECU 84 (see [4]-1, 2). Additionally, it is the synchronization determination time by the BEVECU 84 (see [5]). Furthermore, it is the time to send the switching command of the claw clutch 70 associated with the synchronization determination to the DCSECU 88 (see [6]). Furthermore, it is the time until the DCSECU 88 outputs the operation command of the actuator 72 (see [7]). Furthermore, it is the response delay time of the actuator 72 (see [8]). Furthermore, it is the operation time of the claw clutch 70 (the movement time of the claw teeth) (see [9]). Figure 2 The times [6]-[9] are equivalent to the corresponding time from the point of synchronization to the point of actual engagement. This corresponding time is not variable depending on driving conditions, but is determined uniformly to some extent. This corresponding time is a predetermined time TMf determined in advance from the point of synchronization to the point of engagement start of the opposing meshing teeth. Furthermore, if we consider that the actual left rear wheel rotation speed Nwrl at the point of engagement start, i.e., the rotation speed of the second claw tooth 70b, changes due to acceleration and deceleration, the above can also be considered. Figure 2 The time in [1]-[5] includes the predetermined time TMf.

[0036] Based on the required acceleration or deceleration, BEVECU84 calculates the rotational speed Nwrl of the left rear wheel, i.e., the rotational speed of the second pawl tooth 70b, which varies during a predetermined time TMf. Alternatively, BEVECU84 calculates a predicted value (expected value) of the rotational speed of the second pawl tooth 70b after the predetermined time TMf, based on the required acceleration or deceleration. Based on the rotational speed of the second pawl tooth 70b varying during the predetermined time TMf, or the predicted value of the rotational speed of the second pawl tooth 70b after the predetermined time TMf, BEVECU84 outputs a command to MGECU82 to synchronize the rotational speed of the first pawl tooth 70a with the rotational speed of the second pawl tooth 70b after the predetermined time TMf. MGECU82 corrects the MGR rotational speed Nmgr according to the command to synchronize with the rotational speed of the second pawl tooth 70b after the predetermined time TMf, so that the rotational speed of the first pawl tooth 70a becomes the rotational speed of the second pawl tooth 70b after the predetermined time TMf. In this way, the electronic control device 80 calculates the rotational speed of the second claw tooth 70b after a predetermined time TMf according to the acceleration and deceleration requirements of the vehicle 10, and makes the rotational speed of the first claw tooth 70a change in such a way that the rotational speed of the first claw tooth 70a becomes the rotational speed of the second claw tooth 70b after the predetermined time TMf.

[0037] Figure 3 It is a flowchart illustrating the main part of the control operation of the electronic control device 80, and a flowchart illustrating the control operation used to suppress the generation of sound and impact when the claw clutch 70 is engaged, for example, being repeatedly executed.

[0038] exist Figure 3First, in step S10 (steps omitted below) corresponding to the function of BEVECU84, it is determined whether there is a change during the transition from 2WD control to 4WD state. If the determination in S10 is affirmative, in step S20 (corresponding to the functions of MGECU82 and BEVECU84), the MGR rotational speed Nmgr is increased to begin switching from the disengaged state to the engaged state of the claw clutch 70. Next, in step S30 (corresponding to the function of BEVECU84), it is determined whether the absolute value of the difference between the left rear wheel rotational speed Nwrl and the MGR rotational speed Nmgr is less than a predetermined rotational difference. If the determination in S30 is negative, the process returns to step S20. If the determination in S30 is affirmative, in step S40 (corresponding to the functions of BEVECU84 and DCSECU88), it is determined that the rotational speeds of the relative meshing teeth of the claw clutch 70 are synchronized, and the actuator 72 is activated to engage the claw clutch 70. Next, in S50 corresponding to the function of BEVECU84, the predicted value of the left rear wheel rotation speed Nwrl (= the rotation speed of the second claw tooth 70b) at the engagement start time of the first claw tooth 70a and the second claw tooth 70b after a predetermined time TMf, is calculated according to the required acceleration or deceleration. Next, in S60 corresponding to the functions of MGECU82 and BEVECU84, the rotation speed of MGR Nmgr is changed in a manner that matches the predicted value of the left rear wheel rotation speed Nwrl by changing the rotation speed of the first claw tooth 70a. Next, in S70 corresponding to the function of DCSECU88, it is determined whether the claw clutch 70 has completed engagement. If the determination in S70 is negative, the process returns to S40 above. If the determination in S70 is positive, in S80 corresponding to the function of DCSECU88, it is identified that the claw clutch 70 has completed engagement. If the determination in S10 is negative, in S90, the current control state continues.

[0039] As described above, according to this embodiment, when a switch from 2WD to 4WD is detected, the rotational speed Nmgr of the MGR is increased to synchronize the rotational speeds of the opposing meshing teeth of the claw clutch 70. When the rotational speeds of the opposing meshing teeth are determined to be synchronized, the switch to the engagement state of the claw clutch 70 begins. Furthermore, based on acceleration / deceleration requirements, the rotational speed of the second claw tooth 70b after a predetermined time TMf is calculated. Then, the rotational speed Nmgr of the MGR is varied such that the rotational speed of the first claw tooth 70a becomes the rotational speed of the second claw tooth 70b after a predetermined time TMf. Thus, during the transition from the synchronization detection time point to the engagement start time point of the opposing meshing teeth, the MGR rotational speed Nmgr is corrected to allow the opposing meshing teeth to mesh while maintaining synchronized rotational speeds. Therefore, when the claw clutch 70 is engaged, noise and impact can be suppressed.

[0040] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the present invention can also be applied in other ways.

[0041] For example, in the above embodiments, the power source of the front drive unit 20 may be an engine in addition to the MGF22, or an engine may be used instead of the MGF22. Alternatively, one of the front wheels 12 and the rear wheels 14 may be the rear wheel 14, and the other wheel may be the front wheel 12. In this case, it includes a power source that drives only the rear wheels 14, an electric motor that drives only the front wheels 12, and an engaging clutch provided in the power transmission path between the front wheels 12 and the electric motor.

[0042] Furthermore, the above description is only one embodiment, and the present invention can be implemented in various ways with modifications and improvements based on the knowledge of those skilled in the art.

[0043] (Symbol Explanation)

[0044] 10: Vehicle; 12: Front wheel (one side's wheel); 14: Rear wheel (the other side's wheel); 22: MGF (power source); 32: MGR (electric motor); 70: Claw clutch (engaging clutch); 70a: First claw tooth (engaging tooth on the electric motor side); 70b: Second claw tooth (engaging tooth on the other side's wheel side); 80: Electronic control unit (control device).

Claims

1. A control device of a vehicle that is provided with a power source that drives only one of front wheels and rear wheels, a motor that drives only the other of the front wheels and the rear wheels, and an engagement type clutch that is provided in a power transmission path between the other of the wheels and the motor, characterized by, in a case where it is determined that a switch from a driving state in which only the one of the wheels is driven in a disengaged state of the clutch to an all-wheel drive state in which the front wheels and the rear wheels are driven in an engaged state of the clutch, increasing a rotational speed of the motor in a manner that synchronizes rotational speeds of opposite engagement teeth of the clutch, in a case where it is determined that the rotational speeds of the opposite engagement teeth are synchronized, starting a switch to the engaged state of the clutch, and in accordance with a request for acceleration or deceleration of the vehicle, calculating a rotational speed of an engagement tooth of the other of the wheels in the opposite engagement teeth after a predetermined time from a point in time at which it is determined that the synchronization to a point in time at which engagement of the opposite engagement teeth is started, in a manner that a rotational speed of an engagement tooth of the motor in the opposite engagement teeth becomes the rotational speed of the engagement tooth of the wheels after the predetermined time.

2. The control device according to claim 1, characterized in that, in a case where it is determined that the rotational speeds of the opposite engagement teeth are not synchronized, the rotational speed of the motor is changed in a manner that the rotational speed of the engagement tooth of the motor in the opposite engagement teeth becomes the rotational speed of the engagement tooth of the wheels after the predetermined time.

3. The control device according to claim 1 or 2, characterized in that, in a case where it is determined that the rotational speeds of the opposite engagement teeth are not synchronized, the rotational speed of the motor is changed in a manner that the rotational speed of the engagement tooth of the motor in the opposite engagement teeth becomes the rotational speed of the engagement tooth of the wheels after the predetermined time.

4. The control device according to any one of claims 1 to 3, characterized in that, in a case where it is determined that the rotational speeds of the opposite engagement teeth are not synchronized, the rotational speed of the motor is changed in a manner that the rotational speed of the engagement tooth of the motor in the opposite engagement teeth becomes the rotational speed of the engagement tooth of the wheels after the predetermined time.

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