JP2000343963A - Start-assisting device for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce shock at the time of starting start-assisting, and to restrain the rush current of an electric motor to a low level, in a device constituted to drive the driven wheel of a vehicle by the electric motor to assist the start. SOLUTION: A hydraulic clutch 8 is interposed in a power transmission route between an electric motor 6 and driven wheels 4L, 4R to supply oil to the clutch 8 by a hydraulic pump 10 driven by the motor 6. Oil supplying pressure from the pump 10 is low in a low rotational-speed region of the motor 6 to generate slide of the clutch 8. Driving torques of the driven wheels 4L, 4R are thereby led moderately.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a start assist device mounted on a vehicle having one of a front wheel and a rear wheel as a drive wheel driven by an engine and the other as a driven wheel.

[0002]

2. Description of the Related Art Conventionally, there has been known a start assist device in which an electric motor for a driven wheel is provided, and when the vehicle is started on a slippery road such as a snowy road, the driven wheel is driven by the electric motor to assist starting. I have.

In this motor, an inexpensive DC brush motor used for a cell motor or the like is used as an electric motor.
A dog clutch is interposed in the power transmission path between the electric motor and the driven wheels so that the durability of the brush is not impaired by the over-rotation of the motor due to the reverse drive from the driven wheels after the start. Disengages the dog clutch to disconnect the electric motor from the driven wheel.

[0004]

In the above-mentioned prior art, a sudden rise of the driving torque of the driven wheel occurs at the start of the start assist, so that a shock is likely to occur, and a large inrush current occurs at the beginning of the start of the electric motor. The electric motor that is about to rotate forward may be forced to reverse by the reverse drive from the driven wheel side, and the electric motor may be overloaded. The power supply system for the motor becomes large and the cost increases.

SUMMARY OF THE INVENTION In view of the above, the present invention is capable of reducing the shock at the start of the start assist, further suppressing the inrush current and preventing the overload from acting on the electric motor. It is an object of the present invention to provide a start assist device capable of reducing the cost of a system.

[0006]

In order to solve the above problems,
The present invention is a start assist device mounted on a vehicle in which one of a front wheel and a rear wheel is a drive wheel driven by an engine and the other is a driven wheel, wherein the driven wheel is driven by an electric motor when the vehicle starts. A hydraulic pump driven by the electric motor is provided, and a power transmission path between the electric motor and the driven wheel is provided through a hydraulic clutch connected to the hydraulic pump via a hydraulic circuit. Has been established.

The hydraulic pressure supplied from the hydraulic pump to the hydraulic clutch increases as the rotation speed of the electric motor, which is the drive source of the hydraulic pump, increases. Therefore, when the electric motor is started, slippage occurs in the hydraulic clutch, so that no load is applied to the electric motor to the left, and the rush current is suppressed to a low level. Thereafter, as the rotation speed of the electric motor increases, the engagement force of the hydraulic clutch increases, and torque is transmitted to the driven wheels. As a result, the drive torque of the driven wheels rises gradually, and the shock at the start of the start assist is increased. Is reduced. Also, even if the vehicle moves backwards on a slope, in this case, the hydraulic pressure supplied from the hydraulic pump becomes low and the hydraulic clutch slips, so that the electric motor cannot be forcibly rotated reversely by the reverse drive from the driven wheel side. Therefore, it is possible to prevent an overload from acting on the electric motor.

After the start, the power supply to the electric motor is stopped. However, even after the power supply is stopped, the electric motor and the hydraulic pump are rotated by the reverse drive from the driven wheel side, and the hydraulic clutch remains engaged. The electric motor is over-rotated and its durability is deteriorated.

In this case, the hydraulic circuit includes a forward state in which the hydraulic oil is supplied to the hydraulic clutch only when the electric motor is normally rotated, and a state in which the hydraulic pump is driven only when the electric motor is rotated in the reverse direction. By providing a switching means for switching the oil path connection between a state in which the hydraulic oil is supplied to the hydraulic clutch and a state in which the hydraulic oil is supplied to the hydraulic clutch, it is possible to prevent the electric motor from rotating excessively due to reverse driving from the driven wheel after starting. That is, after the oil passage connection is switched to the forward state by the switching means and the electric motor is driven in the forward direction to assist the start in the forward direction, if the oil path connection is switched to the reverse state, Even if the electric motor is rotated forward by the reverse drive from the driving wheel side, the hydraulic clutch is not supplied with oil, so the hydraulic clutch is released, the connection between the electric motor and the driven wheel is released, and the electric motor is driven in the reverse direction in the forward direction. Is prevented. Similarly, after the oil passage connection is switched to the reverse state and the electric motor is driven in the reverse direction to assist in starting in the reverse direction, if the oil passage connection is switched to the forward state, the hydraulic clutch is released. Thus, reverse driving of the electric motor in the reverse rotation direction is prevented.

[0010] Further, between the electric motor and the hydraulic clutch, an over-rotation of the output member on the hydraulic clutch side in the normal rotation direction is allowed when the input member on the electric motor rotates forward, and when the input member rotates reversely. By providing a two-way clutch that allows the output member to rotate in the reverse direction in the reverse direction, reverse driving of the electric motor after starting can be prevented without providing the switching means. That is, when the electric motor is driven in the forward rotation direction or the reverse rotation direction to assist the start in the forward direction or the reverse direction, the output torque of the electric motor is transmitted to the driven wheels via the two-way clutch and the hydraulic clutch. On the other hand, when the electric motor is not driven, the output member of the two-way clutch can freely rotate in both forward and reverse directions, thereby preventing reverse driving of the electric motor after starting.

[0011]

FIG. 1 shows a front wheel drive vehicle in which right and left front wheels 3L, 3R are driven by an engine 1 via a transmission 2, and the vehicle is started between right and left rear wheels 4L, 4R as driven wheels. An assist device 5 is provided.

The start assist device 5 is, as shown in FIG.
The left and right rear wheels 4L, 4R are driven by an electric motor 6 composed of a DC brush motor via a differential gear 7. A hydraulic clutch 8 is provided in a power transmission path between the electric motor 6 and the differential gear 7. A hydraulic pump 10 composed of a gear pump is provided on a shaft 9 connecting the electric motor 6 and the hydraulic clutch 8, and the oil discharged from the hydraulic pump 10 is supplied to the hydraulic clutch 8 via a hydraulic circuit 11.

As shown in FIG. 3, the hydraulic circuit 11 is provided with an electromagnetic switching valve 12 as switching means. The switching valve 12 discharges oil when the electric motor 6 rotates in the forward direction and sucks oil when rotating in the reverse direction. The oil passage L1 communicates with one port of the hydraulic pump 10 and discharges oil when the electric motor 6 rotates in the reverse direction. An oil passage L2 communicating with the other port of the hydraulic pump 10 that sucks oil during rotation, and an oil passage L3 communicating with the hydraulic clutch 8
When an oil passage L4 which is interposed a relief valve 15 for oil discharge parallel to the check valve 14 ₁ and suction strainer 13 ₁ is connected. Further, the oil passage L3 is an oil passage L5 which is interposed a check valve 14 ₁ and suction strainer 13 _2, an oil passage L6 which is interposed a regulator 16,
Oil passage L provided with check valve 17 for oil discharge and throttle 18
7 are branched and connected.

The switching valve 12 connects the oil passage L1 to the oil passage L3, connects the oil passage L2 to the oil passage L4, and connects the oil passage L1 to the oil passage L4. It can be switched to the reverse position connected to the oil passage L3. In the forward position, when the electric motor 6 is rotated forward, the hydraulic pump 1
0, oil is sucked up through the oil passage L4, and the oil discharged from the hydraulic pump 10 is supplied to the hydraulic clutch 8 through the oil passage L3. Oil is sucked up through road L5,
This oil is supplied from the hydraulic pump 10 to the relief valve 15 of the oil passage L4.
And is not supplied to the hydraulic clutch 8.
In the reverse position, when the electric motor 6 is rotated in the reverse direction, oil is sucked up by the hydraulic pump 10 via the oil passage L4, and oil discharged from the hydraulic pump 10 is supplied to the hydraulic clutch 8 via the oil passage L3. However, when the electric motor is rotated forward, oil is sucked up by the hydraulic pump 10 via the oil passage L5, and the oil is discharged from the hydraulic pump 10 via the relief valve 15 of the oil passage L4, and the hydraulic clutch 8 Is not refueled.

Thus, the switching valve 12 is switched to the forward position to drive the electric motor 6 in the forward direction, or
Is switched to the reverse position and the electric motor 6 is driven in the reverse direction, the output torque of the electric motor 6 is transmitted to the left and right rear wheels 4L and 4R via the hydraulic clutch 8, and the starting assist in the forward or reverse direction is provided. Done. In this case, part of the oil supplied from the hydraulic pump 10 to the oil passage L3
7, the oil pressure is gradually discharged from the hydraulic clutch 8 in response to an increase in the amount of oil discharged from the hydraulic pump 10 as the rotation speed of the electric motor 6 increases. When the pressure is increased to a predetermined pressure defined by the regulator 16, the oil pressure becomes constant. FIG. 4 shows the output torque of the electric motor 6 with respect to the rotation speed of the electric motor 6,
The torque transmission capacity of the hydraulic clutch 10 and the rear wheels 4L, 4R
Shows the relationship with the driving torque. Here, the torque transmission capacity of the hydraulic clutch 10 increases in proportion to the hydraulic pressure input to the hydraulic clutch 10. And the electric motor 6
Since the output torque of the electric motor 6 exceeds the torque that can be transmitted by the hydraulic clutch 10 until the rotation speed of the rear wheel 4 reaches the predetermined value Na, the hydraulic clutch 10 slips and the rear wheels 4
The drive torque of L, 4R rises slowly. In addition, the oil passage L7
Without increasing the pressure, the rise in the hydraulic pressure in the low rotation range of the electric motor 6 is regulated by the leak in the hydraulic pump 10 and the hydraulic clutch 8, so that the sudden rise of the driving torque of the rear wheels 4L and 4R can be prevented. However, if the oil passage L7 is provided as in the present embodiment so that the oil is drained through the throttle 18,
The drive torque of the rear wheels 4L, 4R can be raised more gradually.

The electric motor 6 is supplied with power from a battery 19 via a driver circuit 20. The controller 21 controls the electric motor 6 via the driver circuit 20 and controls switching of the switching valve 12. I'm trying to do it. The controller 21 includes the front wheel 3
Front wheel speed sensor 22 for detecting rotation speed VF of L, 3R
And signals from a rear wheel speed sensor 23 that detects the rotational speed VR of the rear wheels 4L and 4R, a brake switch 24, an accelerator switch 25, and a position sensor 26 of the transmission 2 are input. Start assist control is performed on the basis of.

Details of the start assist control are as shown in FIG. 5. The brake switch 24 is off (S1), the accelerator switch 25 is on (S2), the position of the transmission 2 is a non-neutral position (S3), Rear wheel speed V
R is a predetermined start determination reference value VS (for example, 10 km / h)
When the four conditions of less than (S4) are satisfied, it is determined that the vehicle is starting, and when it is determined that the vehicle is starting, it is determined whether or not the start assist flag F is set to “1” (S4).
5) If F = 0, it is determined whether or not the difference ΔV between the front wheel speed VF and the rear wheel speed VR is equal to or greater than a predetermined reference value ΔVS (S6). If ΔV ≧ △ VS, it is determined that the front wheels 3L and 3R are slipping, the start assist flag F is set to “1” (S7), and then the position of the transmission 2 is set to the forward position. It is determined whether the current position is for the reverse position (S8). If it is in the forward position, the switching valve 12 is switched to the forward position (S9), and the electric motor 6 is driven in the forward direction (S1).
0) If it is in the reverse position, the switching valve 12 is switched to the reverse position (S11), and the electric motor 6 is driven in the reverse direction (S12).

According to this, the output torque of the electric motor 6 is transmitted to the rear wheels 4L and 4R via the hydraulic clutch 10 to assist in starting in the forward or reverse direction.
In this case, since the driving torque of the rear wheels 4L and 4R rises gently as described above, the shock at the start of the start assist is reduced, and the rush current of the electric motor 6 is suppressed low. When the load on the electric motor 6 increases, the hydraulic pressure of the hydraulic clutch 10 decreases due to the decrease in the rotation speed of the electric motor 6, and the hydraulic clutch 10 slips. Therefore, even if the vehicle moves backward when starting on a hill, the electric motor 6 is driven by the rear wheel 4.
It is possible to prevent the electric motor 6 from being overloaded by the reverse drive from the L and 4R sides without forcibly reverse rotation. As described above, the rush current can be suppressed low and the overload can be prevented.
The capacity of b can be small, and the cost of the power supply system for the electric motor 6 can be reduced.

After the start, if VR ≧ VS, the start assist flag F is reset to “0” (S13), and then the position of the transmission 2 is set to the neutral position, the forward position, and the reverse position. The position is determined (S14). When it is in the forward position, the switching valve 12 is switched to the reverse position (S1).
5) If it is in the reverse position, the switching valve 12 is switched to the forward position (S16), and then the driving of the electric motor 6 is stopped (S17). When the switch is in the neutral position, the drive of the electric motor 6 is stopped without switching the switching valve 12.

When the switching valve 12 is switched as described above, no oil is supplied to the hydraulic clutch 8, the hydraulic clutch 8 is released, and the connection between the electric motor 6 and the rear wheels 4L and 4R is released. Thus, the electric motor 6 is prevented from being over-rotated by the reverse drive from the rear wheels 4L and 4R after the start.

FIG. 6 shows a second embodiment of the start assist device 5, and the same members as those in the first embodiment are denoted by the same reference numerals. The main difference between the second embodiment and the first embodiment is that a two-way clutch 27 is provided between the electric motor 6 and the hydraulic clutch 8.

In the embodiment shown in FIG.
Although the two-way clutch 27 is provided between the hydraulic pump 10 and the hydraulic pump 10, a two-way clutch 27 may be provided between the hydraulic pump 10 and the electric motor 6.

As shown in FIG. 7, the two-way clutch 27 includes an outer member 270 as an input member having a gear 270a meshing with a gear 6a connected to the electric motor 6, and an inner member 271 as an output member connected to the hydraulic clutch 8. When,
As shown in FIG. 8, a plurality of sprags 27 arranged at intervals in the circumferential direction between outer 270 and inner 271.
2, an outer retainer 273 press-fitted and fixed to the inner periphery of the outer 270, and a regulating pin 27 on the inner periphery of the outer retainer 273.
The inner retainer 274 is disposed so as to be rotatable relative to the outer retainer 273 by a predetermined angle regulated by 4a. The gear 275b meshes with the gear 6a.

In FIG. 8, when the clockwise direction is the forward direction, the inner retainer 274 is rotationally displaced in the reverse direction with respect to the outer retainer 273. In the state of FIG. 8B in which the inner retainer 274 is rotationally displaced in the normal rotation direction with respect to the outer retainer 273, the inner rotation of the inner 271 in the reverse rotation direction with respect to the outer 270 is permitted. You.

The number of teeth of the gear 275b is larger than the number of teeth of the gear 270a by a predetermined number (for example, one tooth), and the gear 27 shown by a solid line in FIG.
When the gear 270a is rotated in the forward direction, the gear 275b indicated by a dotted line in FIG. The inner retainer 274 frictionally engaged with the switching plate 275 integral with the gear 275b is rotationally displaced in the reverse direction to switch to the state shown in FIG. 8A, and the inner 271 is allowed to rotate in the forward direction. . When the electric motor 6 rotates the gear 270a in the reverse direction via the gear 6a, the gear 2
The gear 275b is relatively rotated in the normal rotation direction with respect to 70a, and is switched to the state shown in FIG. 8B, so that the inner 271 is allowed to rotate in the reverse rotation direction. When the inner motor 271 rotates in the reverse direction in the state shown in FIG. 8A when the driving of the electric motor 6 is stopped, the outer 270 also temporarily rotates in the reverse direction in the state shown in FIG. The rotation of the gear 6a causes the gear 275b to rotate relative to the gear 270a in the normal rotation direction to switch to the state shown in FIG. 8B, and thereafter the inner 271 freely rotates in the reverse rotation direction. When the inner motor 271 rotates in the normal rotation direction in the state of FIG. 8B when the driving of the electric motor 6 is stopped, the gear 270a and the gear 6a rotate through the gear 270a and the gear 6a due to the temporary rotation of the outer 270 in the normal rotation direction. 275b rotates relative to the gear 270a in the reverse direction to switch to the state shown in FIG. 8A, and thereafter the inner 271 freely rotates in the normal direction.

Thus, when the drive of the electric motor 6 is stopped after the start, the inner 271 can rotate freely in both the forward and reverse directions, and the transmission of the reverse drive force from the rear wheels 4L, 4R to the electric motor 6 is performed. Will be blocked. Therefore, even if the switching valve 12 of the first embodiment is not provided, the rear wheels 4L,
Excessive rotation of the electric motor 6 due to reverse driving from the 4R side is prevented.

The hydraulic circuit 11 for connecting the hydraulic pump 10 and the hydraulic clutch 8 is provided with a bridge circuit 28 incorporating four check valves 14 as shown in FIG. The hydraulic circuit 10 is connected to an oil passage L3 connected to the hydraulic clutch 8 on the discharge side of the bridge circuit 30 so as to supply oil from the hydraulic pump 10 to the hydraulic clutch 8 by either forward or reverse rotation of the electric motor 6. I am trying to be. In addition, oil passage L3
The oil passage L6 interposed with the regulator 16 and the throttle 18
And the oil passage L7 for draining is branched and connected so that the drive torque of the rear wheels 4L and 4R rises gently as in the first embodiment.

In the second embodiment, since the switching valve 12 is not required, the start assist control is performed in steps S9, S11,
This is performed according to a program in which steps S14, S15, and S16 are deleted.

Although the start assist device for a front wheel drive vehicle has been described above, the present invention can be similarly applied to a start assist device for a rear wheel drive vehicle.

[0030]

As is apparent from the above description, according to the present invention, the sudden rise of the driving torque of the driven wheel at the start of the start assist can be prevented, the shock can be reduced, and the rush current can be reduced. It is possible to reduce the cost of the power supply system by suppressing the overload from acting on the electric motor while suppressing the electric motor.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of use of the apparatus of the present invention.

FIG. 2 is a skeleton diagram showing a first embodiment of the device of the present invention.

FIG. 3 is a circuit diagram showing a hydraulic circuit according to the first embodiment.

FIG. 4 is a graph showing changes in the output torque of the electric motor, the torque transmission capacity of the hydraulic clutch, and the rear wheel drive torque with respect to the rotation speed of the electric motor.

FIG. 5 is a flowchart showing a start assist control program.

FIG. 6 is a skeleton diagram showing a second embodiment of the device of the present invention.

FIG. 7 is a sectional view of a two-way clutch.

8A is a diagram illustrating a state of a two-way clutch during forward rotation, and FIG. 8B is a diagram illustrating a state of a two-way clutch during reverse rotation.

FIG. 9 is a diagram showing a meshing state of a switching plate gear of the two-way clutch.

FIG. 10 is a circuit diagram showing a hydraulic circuit according to a second embodiment.

[Explanation of symbols]

Reference Signs List 1 engine 3L, 3R front wheel (drive wheel) 4L, 4R rear wheel (follower wheel) 5 start assist device 6 electric motor 8 hydraulic clutch 10 hydraulic pump 11 hydraulic circuit 12 switching valve (switching means) 27 two-way clutch

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Shigeru Tajima 1-4-1 Chuo, Wako-shi, Saitama F-term in Honda R & D Co., Ltd. (Reference) 3D039 AA01 AA02 AA05 AA07 AB27 AC03 AC54 AC88 AD01 AD43 AD44 3D043 AA05 AA08 AB17 EA02 EA05 EA11 EA41 EA45 EB03 EB06 EB12 EE02 EE03 EE07 EE09 EF02 EF06 EF09 EF12 EF16 EF24 5H115 PG04 PI13 PI29 PU11 PU25 QE01 QE15 QH02 RB08 SE03 TB02 TR04 TU02

Claims (3)

[Claims] 1. A starting assist device mounted on a vehicle having one of a front wheel and a rear wheel as a driving wheel driven by an engine and the other as a driven wheel, wherein the driven wheel is driven by an electric motor when the vehicle starts moving. In the above configuration, a hydraulic pump driven by the electric motor is provided, and a power transmission path between the electric motor and the driven wheel is provided.
A starting assist device for a vehicle, comprising a hydraulic clutch connected to the hydraulic pump via a hydraulic circuit. 2. A hydraulic circuit according to claim 1, wherein said hydraulic circuit includes a forward movement state in which oil discharged from said hydraulic pump is supplied to said hydraulic clutch only when said electric motor is normally rotating, and a hydraulic pump circuit which receives said hydraulic oil only when said electric motor is rotating in reverse. 2. The vehicle start assist device according to claim 1, further comprising switching means for switching an oil path connection between a reverse state in which discharge oil is supplied to the hydraulic clutch. 3. An over-rotation of the output member on the hydraulic clutch side in the forward direction between the electric motor and the hydraulic clutch during forward rotation of the input member on the electric motor side, and when the input member reversely rotates. 2. The vehicle start assist device according to claim 1, further comprising a two-way clutch that allows over-rotation of the output member in the reverse direction.