JP2012121447A - Drive system for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a drive system for a vehicle capable of properly securing controllability of a motor at the occurrence of a slip.SOLUTION: The drive system 1 for the vehicle can achieve hybrid traveling with an engine 2 and a motor 6 as a power source. Further, the drive system 1 for the vehicle includes a clutch 3 disposed between the engine 2 and the motor 6 and capable of controlling clutch torque, and a control device 8 for controlling the clutch torque of the clutch 3, and the control device 8 increases the clutch torque of the clutch 3 when slips occur for wheels 11R, 11L during motor traveling with the motor 6 as the power source.

Description

  The present invention relates to a vehicle drive system, and more particularly to a vehicle drive system that can appropriately ensure the controllability of a motor when a slip occurs.

  In a conventional vehicle drive system, when a slip occurs on a drive wheel during running of the motor, the drive of the motor is controlled to suppress the slip of the drive wheel. As such a conventional vehicle drive system, a technique described in Patent Document 1 is known.

JP 2010-203593 A

  However, since the conventional vehicle drive system controls the motor rotation speed by driving the motor, there is a problem that the controllability deteriorates when the motor rotation speed increases.

  Therefore, the present invention has been made in view of the above, and an object of the present invention is to provide a vehicle drive system that can appropriately ensure the controllability of a motor when a slip occurs.

  In order to achieve the above object, a vehicle drive system according to the present invention is a vehicle drive system capable of realizing hybrid travel using an engine and a motor as power sources, and is disposed between the engine and the motor. A clutch capable of controlling the clutch torque, and a control device for controlling the clutch torque of the clutch, and the control device is used when the motor is driven with the motor as a power source and slipping occurs on the wheels. The clutch torque of the clutch is increased.

  In the vehicle drive system according to the present invention, it is preferable that the control device determines that a slip has occurred in the wheel when the rate of change of the motor rotation speed of the motor becomes a predetermined threshold value or more. .

  In the vehicle drive system according to the present invention, the control device increases the clutch torque of the clutch and when the rate of change of the motor rotation speed of the motor becomes a predetermined threshold value or less. It is preferable to reduce the clutch torque of the clutch.

  In the vehicle drive system according to the present invention, excess rotational energy of the motor generated by the slip is transmitted to the engine via the clutch and absorbed as rotational energy of the engine. Then, an increase in the motor rotation speed is suppressed, and the motor torque is held in a region with good controllability. Thereby, there is an advantage that the controllability of the motor can be appropriately ensured even when slipping occurs.

FIG. 1 is a configuration diagram showing a vehicle drive system according to an embodiment of the present invention. FIG. 2 is a flowchart showing the operation of the vehicle drive system shown in FIG. FIG. 3 is a time chart showing the operation of the vehicle drive system shown in FIG. FIG. 4 is an explanatory diagram showing the operation of the vehicle drive system shown in FIG.

  Hereinafter, the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments. Further, the constituent elements of this embodiment include those that can be replaced while maintaining the identity of the invention and that are obvious for replacement. In addition, a plurality of modifications described in this embodiment can be arbitrarily combined within a range obvious to those skilled in the art.

[Vehicle drive system]
FIG. 1 is a configuration diagram showing a vehicle drive system according to an embodiment of the present invention.

  The vehicle drive system 1 includes an engine 2, a clutch 3, a transmission 4, a deceleration differential device 5, a motor 6, a sensor unit 7, and a control device 8 (see FIG. 1). The vehicle drive system 1 is applied to, for example, a hybrid vehicle capable of realizing hybrid travel that switches between engine travel using the engine 2 as a power source and motor travel using the motor 6 as a power source.

  The engine 2 is a first power source, generates drive torque and outputs it from the output shaft 21. The engine 2 is an internal combustion engine or an external combustion engine. For example, in this embodiment, a reciprocating engine using gasoline as fuel is employed.

  The clutch 3 is a mechanical element that switches between permitting and shutting off transmission of driving torque. Further, the clutch 3 can change its clutch torque (transmission torque capacity). The clutch 3 includes an input-side rotating unit 31 and an output-side rotating unit 32, and is connected to the output shaft 21 of the engine 2 at the input-side rotating unit 31 and is arranged at the rear stage of the engine 2. The clutch 3 permits torque transmission in the engaged state of the input side rotating unit 31 and the output side rotating unit 32, and interrupts torque transmission in the released state. The clutch 3 includes a hydraulic mechanism (not shown), and adjusts the engagement force between the input-side rotating unit 31 and the output-side rotating unit 32 by the hydraulic mechanism to change the clutch torque. For example, a friction clutch can be adopted as the clutch 3.

  The transmission 4 is an automatic transmission that can automatically change the gear position (or gear ratio). Further, the transmission 4 has an input shaft 41 and an output shaft 42, and is connected to the output-side rotating portion 32 of the clutch 3 by the input shaft 41 and is arranged at the rear stage of the clutch 3. Further, the transmission 4 can change its gear ratio = (the number of revolutions of the output shaft 42) / (the number of revolutions of the input shaft 41) by switching the gear stage. As the transmission 4, a stepped transmission, a belt type or a toroidal type continuously variable transmission can be adopted. For example, in this embodiment, the transmission 4 has a gear type that can switch between a neutral (N range), four forward stages 43 to 46 (D range), and one reverse stage 47 (R range). The stepped automatic transmission is adopted.

  The deceleration differential device 5 is a mechanical element that decelerates the drive torque and distributes it to the left and right wheels 11R and 11L of the vehicle. The deceleration differential device 5 includes an input shaft 51, a deceleration mechanism 52 that decelerates the drive torque, and a differential mechanism 53 that adjusts the distribution of the drive torque to the left and right wheels of the vehicle. The reduction differential 5 is connected to the output shaft 42 of the transmission 4 by the input shaft 51 and is connected to the axles 12 of the wheels 11R and 11L by the differential mechanism 53.

  The motor 6 is a second power source, generates drive torque and outputs it from the output shaft 61. The motor 6 is connected to the output shaft 42 of the transmission 4 by an output shaft 61. For example, in this embodiment, an AC synchronous motor generator having a motor function and a generator function is employed as the motor 6.

  In this embodiment, the motor 6 is always connected to the output shaft 42 of the transmission 4 (see FIG. 1). However, the present invention is not limited thereto, and the motor 6 and the output shaft 42 of the transmission 4 may be configured to be connected and disconnected via a motor clutch (not shown). Further, the motor 6 and the input shaft 41 of the transmission 4 may be configured to be connected and disconnected via a motor clutch (not shown). Further, the connection between the motor 6 and the input shaft 41 and the output shaft 42 of the transmission 4 may be switched between each other (not shown).

  The sensor unit 7 is, for example, a sensor group for acquiring information related to the vehicle state quantity and the travel path. The sensor unit 7 includes an accelerator opening sensor 71 that detects an accelerator opening θ, a shift position sensor 72 that detects a shift position of the transmission 4, and a clutch position (a position for engagement and disengagement) of the clutch 3 or A clutch sensor 73 that detects the clutch torque, a wheel speed sensor 74 that detects the wheel speed of each of the wheels 11R and 11L, and an engine speed sensor 75 that detects the rotation speed (engine speed) Ne of the output shaft 21 of the engine 2. And a motor rotation speed sensor 76 for detecting the rotation speed (motor rotation speed) Nm of the output shaft 61 of the motor 6.

  The control device 8 is a device that controls the operation of the vehicle drive system 1, and includes, for example, an ECU (Electrical Control Unit). The control device 8 outputs a predetermined output signal based on the output signal of the sensor unit 7. The control device 8 includes a motor rotation number increase suppression control unit 81 that performs motor rotation number maintenance control at the time of occurrence of slip, which will be described later, a slip determination unit 82 that determines occurrence of slip, and an engine control unit that controls driving of the engine 2. 83, a clutch control unit 84 for driving and controlling the clutch 3, a transmission control unit 85 for driving and controlling the transmission 4, a motor control unit 86 for driving and controlling the motor 6, and predetermined information (for example, various controls) A storage unit 87 for storing a program, control data such as a control map and a threshold). The control device 8 drives and controls the engine 2, the clutch 3, the transmission 4 and the motor 6 based on the output signal of the sensor unit 7. Thereby, various controls are realized.

  In the vehicle drive system 1, when the vehicle engine is running, the control device 8 drives the engine 2 with the clutch 3 engaged. Then, the engine 2 generates drive torque, and this drive torque is transmitted to the transmission 4 via the clutch 3. Then, this drive torque is shifted by the transmission 4, decelerated by the deceleration differential 5, and distributed to the left and right wheels 11 </ b> R and 11 </ b> L of the vehicle. Thereby, the vehicle travels using the engine 2 as a power source.

  On the other hand, when the vehicle runs on the motor, the control device 8 opens the clutch 3 to separate the engine 2 from the drive system on the axle side and drives the motor 6. Then, the motor 6 generates a driving torque, and this driving torque is distributed to the left and right wheels 11R and 11L of the vehicle via the deceleration differential device 5. As a result, the vehicle travels using the motor 6 as a power source.

  In addition, the vehicle drive system 1 can realize hybrid travel using both engine travel and motor travel. For example, when the vehicle starts or travels at a low speed, the control device 8 stops the engine 2 and drives the motor 6 to drive the motor 6, and during a medium or high speed travel, the control device 8 stops the motor 6 and the engine. The engine travels by driving 2. Further, switching between engine running and motor running is performed according to the vehicle speed and the state of charge of a battery (not shown). Thereby, efficient driving | running | working is implement | achieved and a fuel consumption improves.

[Control of motor speed increase when slip occurs]
FIG. 2 is a flowchart showing the operation of the vehicle drive system shown in FIG. This figure shows a flowchart of the motor rotation speed increase suppression control when a slip occurs.

  In general, when slipping occurs in a tire during running of the motor, the motor speed increases due to idling of the drive wheels. Then, the operating state of the motor shifts from the sine wave control region A with good controllability to the variable length control region B or the rectangular wave control region C (see the broken line in FIG. 4). Then, controllability of the motor torque is deteriorated and control delay or the like may occur, which is not preferable.

  Therefore, in the vehicle drive system 1, when a slip occurs in the tire while the motor is running, control is performed to suppress an increase in the motor rotation speed caused by the occurrence of the slip. Hereinafter, the motor rotation speed increase suppression control will be described (see FIG. 2).

  In step ST1, it is determined whether or not the motor is running. Motor running refers to a running state using the motor 6 as a power source. When the motor travels, the motor 6 is energized to generate drive torque, which is transmitted to the axle 12 and the vehicle travels. In addition, the clutch 3 is set to an open state, and transmission of driving torque from the engine 2 to the axle 12 is cut off. At this time, the gear position of the transmission 4 may be set to any one of the forward gears. In this embodiment, the clutch sensor 73 detects the clutch position or the clutch torque and outputs a detection signal to the control device 8 when the vehicle is traveling. Then, the control device 8 makes an affirmative determination when the clutch 3 is in an open state and the motor 6 is energized to generate drive torque. If an affirmative determination is made in step ST1, the process proceeds to step ST2, and if a negative determination is made, the process ends.

  In step ST2, it is determined whether or not a slip has occurred. For example, in this embodiment, the motor rotation speed sensor 76 detects the motor rotation speed Nm and outputs it to the control device 8 when the vehicle is traveling. Then, the control device 8 calculates the rate of change ΔNm / Δt of the motor rotational speed Nm at the predetermined sampling time Δt, and the rate of change ΔNm / Δt and the predetermined threshold k1 read from the storage unit 87 are ΔNm / Δt ≧ When the relationship is k1, it is estimated that a slip has occurred, and an affirmative determination is made. If an affirmative determination is made in step ST2, the process proceeds to step ST3, and if a negative determination is made, the process ends.

  In this embodiment, as described above, the slip determination (step ST2) is performed based on the motor rotation speed Nm. However, the present invention is not limited to this, and the slip determination may be determined based on the wheel speed Vw and the vehicle body speed Vv. For example, when the vehicle travels, the wheel speed sensor 74 detects the wheel speed Vw of the drive wheels 11R and 11L and outputs it to the control device 8. Then, the control device 8 calculates the vehicle body speed Vv based on these wheel speeds Vw, and calculates the slip rate S (= (Vv−Vw) / Vv) based on these. Then, when the slip ratio S is equal to or greater than a predetermined threshold, an affirmative determination is made.

  In step ST3, the clutch torque Tc is increased by a predetermined increase amount ΔTc. At this time, when the clutch 3 is in the disengaged state, control for bringing the clutch 3 into an engaged state is performed. When the clutch torque Tc increases, excess rotational energy of the motor 6 generated by slipping (idling of the drive wheels 11R and 11L) is absorbed as rotational energy of the engine 2, and an increase in the motor rotational speed Nm is suppressed. In this embodiment, the control device 8 drives and controls the hydraulic mechanism (not shown) of the clutch 3 to increase the clutch torque. Further, the increase amount ΔTc of the clutch torque Tc is set to be constant. After this step ST3, the process proceeds to step ST4.

  In step ST4, it is determined whether or not the rate of change ΔNm / Δt of the motor rotation speed Nm during a predetermined sampling time Δt is equal to or less than a predetermined threshold value k2. That is, in the case of ΔNm / Δt ≦ k2, it can be said that the clutch torque Tc is appropriate and the increase in the motor rotation speed Nm is suppressed. On the other hand, when ΔNm / Δt> k2, it can be said that the clutch torque Tc needs to be further increased because the clutch torque is insufficient. In this embodiment, the control device 8 makes this determination based on the output signal of the motor rotation number sensor 76 and the predetermined threshold value k2 read from the storage unit 87. If an affirmative determination is made in step ST4, the process proceeds to step ST5, and if a negative determination is made, the process returns to step ST3. That is, if the determination is negative (clutch torque Tc is insufficient), the process returns to step ST3 in order to further increase the clutch torque Tc.

  In step ST5, the clutch torque Tc is decreased by a predetermined decrease amount ΔTc ′. That is, control is performed to decrease and return the clutch torque Tc increased by the clutch torque increase control (step ST3 and step ST4). In this embodiment, the control device 8 controls the hydraulic mechanism of the clutch 3 to reduce the clutch torque. Further, the reduction amount ΔTc ′ of the clutch torque Tc is set to be constant. After this step ST5, the process proceeds to step ST6.

  In step ST6, it is determined whether or not the motor rotational speed Nm has returned to the rotational speed before the occurrence of slip. That is, it is determined by the clutch torque reduction control (step ST5) whether or not the motor rotational speed Nm has converged to an appropriate rotational speed corresponding to the motor torque Tm. In this embodiment, the control device 8 makes this determination. If an affirmative determination is made in step ST6, the process proceeds to step ST7, and if a negative determination is made, the process returns to step ST5. That is, if the determination is negative (the motor rotation speed Nm has not returned to the rotation speed before the occurrence of slip), the process returns to step ST5 in order to further reduce the clutch torque Tc.

  Note that the return determination (step ST6) of the motor rotation speed Nm can be performed as follows. For example, (1) the controller 8 stores the motor rotation speed Nm immediately before the occurrence of slip (sampling time immediately before the positive determination in step ST2) in the storage unit 87, and the motor rotation speed immediately before the occurrence of slip An affirmative determination is made when the difference between Nm and the current motor rotation speed Nm is equal to or less than a predetermined threshold value. Alternatively, (2) the control device 8 calculates the vehicle body speed Vv based on the wheel speed Vw of each of the wheels 11R and 11L, and the difference between the wheel speed Vw applied to the slip determination (step ST2) and the vehicle body speed Vv is predetermined. An affirmative determination is made when the threshold value is reached.

  In step ST7, the clutch 3 is released. As a result, the engine 2 is separated from the drive system and returns to the motor running state before the occurrence of slip. After this step ST7, the process is terminated.

[Specific example of motor speed increase control]
FIG. 3 is a time chart (FIG. 3) and an explanatory diagram (FIG. 4) showing the operation of the vehicle drive system shown in FIG. These drawings respectively show a time chart and an explanatory diagram of an embodiment of the motor rotation speed increase suppression control when slip occurs. Hereinafter, this embodiment will be described with reference to FIGS.

  At t = t0, the vehicle is running on a motor (affirmative determination in step ST1) (see FIGS. 2 and 3). Further, no slip has occurred in each of the wheels 11R and 11L (see FIG. 3A). Further, the accelerator opening degree θ is maintained constant, and the vehicle is traveling at a constant speed (see FIG. 3B). For this reason, the wheel speed Vw of each wheel 11R, 11L is constant (refer FIG.3 (c)). Further, the motor 6 outputs a constant motor torque Tm (see FIG. 3D). Further, the clutch 3 is in the released state, and the clutch torque Tc is Tc = 0 [rpm] (see FIG. 3E). Further, the engine 2 is stopped and the engine torque Te (output torque) is Te = 0 [rpm] (see FIG. 3F). Further, the motor rotation speed Nm is constant (see FIG. 3G), and the engine rotation speed Ne is Ne = 0 [rpm] (see FIG. 3H).

  From t = t1 to t2, tire idling occurs due to changes in the road surface gap and road surface friction coefficient of the traveling road. Then, the wheel speed Vw and the slip ratio S are increased, the load on the wheels 11R and 11L is decreased, and the motor rotation speed Nm is increased (see FIGS. 3A, 3C, and 3G). When the rate of change ΔNm / Δt of the motor rotation speed Nm in the predetermined sampling time Δt becomes equal to or greater than a predetermined threshold k1 (ΔNm / Δt ≧ k1), the control device 8 detects the occurrence of slip (affirmative determination in step ST2). ).

  At t = t2 to t3, the control device 8 starts clutch torque increase control (step ST3 and step ST4). At this time, when the clutch 3 is in the released state, the control device 8 drives the hydraulic mechanism (not shown) of the clutch 3 to bring the clutch 3 into the engaged state. Further, the gear position of the transmission 4 is set to one of the forward gears (not shown). In this clutch torque increase control, the control device 8 drives and controls the hydraulic mechanism of the clutch 3 to increase the clutch torque Tc by a predetermined increase amount ΔTc (see FIG. 3E). Then, excess rotational energy of the motor 6 generated by slip (wheel idling) is absorbed as rotational energy of the engine 2, and an increase in the motor rotational speed Nm is suppressed (see FIG. 3G). Along with this, the engine speed Ne increases (see FIG. 3 (h)).

  When the increase in the motor rotation speed Nm is suppressed, the motor torque Tm is held in a region with good controllability (particularly, the sine wave control region A) (see FIG. 4). Thereby, the controllability of the motor 6 is ensured appropriately even when slipping occurs.

  At t = t3 to t4, the clutch torque increase control (steps ST3 and ST4) or the wheel speed Vw and the slip rate S are reduced by returning the tire contact state (see FIGS. 3A and 3C). The motor rotation speed Nm begins to decrease. When the change rate ΔNm / Δt of the motor rotation speed Nm becomes equal to or less than the predetermined threshold k2 (ΔNm / Δt ≦ k2), the control device 8 ends the clutch torque increase control (Yes determination in step ST4).

  From t = t4 to t5, the control device 8 performs clutch torque reduction control (step ST5 and step ST6). In this clutch torque reduction control, the controller 8 controls the hydraulic mechanism of the clutch 3 to reduce the clutch torque Tc by a predetermined reduction amount ΔTc ′ (see FIG. 3E).

  At t = t5, the motor rotational speed Nm returns to the rotational speed before the occurrence of slip (see FIG. 3G). Then, control device 8 releases clutch 3 and separates motor 6 and engine 2 (affirmative determination in step ST6 and step ST7). As a result, the motor travels before the occurrence of slip.

[effect]
As described above, the vehicle drive system 1 is disposed between the engine 2 and the motor 6 and can control the clutch torque (transmission torque capacity) Tc and the clutch torque Tc of the clutch 3. And a control device 8 (see FIG. 1). Then, when the motor 8 is running with the motor 6 as a power source and slip occurs in the wheels 11R and 11L (affirmative determination in step ST1 and affirmative determination in step ST2), the control device 8 determines the clutch torque of the clutch 3. Tc is increased (step ST3) (see FIG. 2).

  In such a configuration, excess rotational energy of the motor 6 generated by the slip is transmitted to the engine 2 via the clutch 3 and absorbed as rotational energy of the engine 2. Then, the increase in the motor rotation speed Nm is suppressed, and the motor torque Tm is held in a region with good controllability (particularly, the sine wave control region A) (see FIGS. 3G, 3D, and 4). . Thereby, there is an advantage that the controllability of the motor 6 can be appropriately ensured even when slipping occurs. In addition, such a configuration has an advantage that a control delay hardly occurs as compared with a configuration (not shown) in which the motor is driven and controlled to control the motor rotation speed.

  Further, in this vehicle drive system 1, the control device 8 indicates that slip has occurred in the wheels 11R and 11L when the rate of change ΔNm / Δt of the motor rotation speed Nm of the motor 6 is equal to or greater than a predetermined threshold k1. Determine (affirmative determination in step ST2) (see FIG. 2). In such a configuration, control for increasing the clutch torque Tc is performed based on the motor rotation speed Nm to be controlled (step ST3). Thereby, there exists an advantage by which the raise suppression control of motor rotation speed Nm is performed appropriately.

  Further, in this vehicle drive system 1, the controller 8 increases the clutch torque Tc of the clutch 3 (step ST3), and the rate of change ΔNm / Δt of the motor rotation speed Nm of the motor 6 is a predetermined threshold value. When k2 or less, the clutch torque Tc of the clutch 3 is decreased (step ST5) (see FIG. 2). Accordingly, there is an advantage that it is possible to prevent a situation in which the increase in the clutch torque Tc becomes excessive.

  As described above, the vehicle drive system according to the present invention is useful in that the controllability of the motor can be appropriately ensured when a slip occurs.

DESCRIPTION OF SYMBOLS 1 Vehicle drive system, 2 Engine, 21 Output shaft, 3 Clutch, 31 Input side rotation part, 32 Output side rotation part, 4 Transmission, 41 Input shaft, 42 Output shaft, 43-46 Forward speed, 47 Reverse speed, 5 speed differential device, 51 input shaft, 52 speed reduction mechanism, 53 differential mechanism, 6 motor, 61 output shaft, 7 sensor unit, 71 accelerator opening sensor, 72 shift position sensor, 73 clutch sensor, 74 wheel speed sensor, 75 engine speed sensor, 76 motor speed sensor, 8 control device, 81 motor speed maintenance control section, 82 slip determination section, 83 engine control section, 84 clutch control section, 85 transmission control section, 86 motor control section, 87 storage, 11R, 11L wheels, 12 axles

Claims (3)

A drive system for a vehicle capable of realizing hybrid travel using an engine and a motor as a power source,
A clutch disposed between the engine and the motor and capable of controlling a clutch torque; and a control device for controlling the clutch torque of the clutch; and
The control device increases the clutch torque of the clutch when the motor travels using the motor as a power source and slipping occurs on a wheel.   2. The vehicle drive system according to claim 1, wherein the control device determines that a slip has occurred in the wheel when a rate of change of the motor rotation speed of the motor becomes equal to or greater than a predetermined threshold value.   2. The control device according to claim 1, wherein the control device decreases the clutch torque of the clutch after increasing the clutch torque of the clutch and when the rate of change in the motor rotation number of the motor becomes a predetermined threshold value or less. 3. The vehicle drive system according to 2.

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