Starting assistance device

Abstract

Provided is a setting-off assistance device that can reduce the consumption of power during a stop, and reduce any discomfort when setting off. This setting-off assistance device comprises: a first gear mechanism (20) that transmits, to an output shaft, the torque of a first shaft (14) to which the torque of a first drive device (12) is transmitted; a second gear mechanism (30) that transmits, to the output shaft, at a lower reduction ratio than the reduction ratio of the first gear mechanism, the torque of a second shaft (15) positioned coaxially with respect to the first shaft, the torque of a second drive device (13) being transmitted to the second shaft; a first clutch (40) that transmits / interrupts driving power between the first shaft and the second shaft; a second clutch (23) comprising a one-way clutch that transmits, to the output shaft, the rotation of the first gear mechanism when the vehicle is moving forward; and a control device (50) that operates the first clutch. At least one of the first drive device and the second drive device is a motor, and the control device engages the first clutch when the vehicle is at or below a prescribed speed and is on an uphill slope.

Description

Technical Field

[0001] The present invention relates to a starting assist device that prevents a vehicle from moving backward when starting on a slope.

Background Art

[0002] Vehicles equipped with a function to prevent the vehicle from moving backward when starting on a slope (so-called hill start assist) are known. In the technology disclosed in Patent Document 1, the braking force of the vehicle's braking device (hydraulic brake) is used to stop the vehicle.

[0003] In the technology disclosed in Patent Document 2, in a vehicle equipped with a motor that outputs the driving force of the vehicle, the driving force of the motor is used to stop the vehicle. However, since the rotation angle of the motor does not change while the vehicle is stopped, there is a risk that current continues to flow through a specific circuit of the motor and the motor overheats. Therefore, the temperature of the motor and the time during which the vehicle is stopped using the driving force of the motor are monitored, and when they satisfy predetermined conditions, the output of the motor is stopped, and the braking force of the vehicle's braking device is used instead of the driving force of the motor to stop the vehicle.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the technologies disclosed in Patent Documents 1 and 2, since the braking device is used to stop the vehicle on a slope, it takes some time from the start operation until the braking force of the braking device disappears. If the braking force of the braking device is large, there is a risk of feeling a sense of being dragged by the braking force during starting. If the braking force of the braking device is small, or if the braking force disappears before the driving force is generated, the vehicle may reverse. In particular, since the motor disclosed in Patent Document 2 has a large starting torque, the speed at which the braking force of the braking device decreases tends to be slower than the speed at which the driving force of the motor increases, and it is easy to feel a sense of being dragged by the braking force during starting. There is a problem that the electricity cost deteriorates because power is consumed while the vehicle is stopped using the driving force of the motor.

[0006] The present invention has been made to solve this problem, and an object thereof is to provide a starting assist device that can reduce power consumption during stopping and reduce discomfort during starting.

Means for Solving the Problems

[0007] To achieve this object, the starting assist device of the present invention includes a first gear mechanism that transmits the torque of a first shaft to which the torque of a first drive device is transmitted to an output shaft, and a second shaft disposed coaxially with the first shaft, and transmits the torque of the second shaft to which the torque of the second drive device is transmitted to the output shaft at a reduction ratio smaller than the reduction ratio of the first gear mechanism. A second gear mechanism, a first clutch that transmits and cuts off power between the first shaft and the second shaft, a second clutch that includes a one-way clutch that transmits the rotation of the first gear mechanism when the vehicle moves forward to the output shaft, and a control device that operates the first clutch. At least one of the first drive device and the second drive device is a motor, and the control device engages the first clutch when the vehicle is at a speed equal to or lower than a predetermined speed and on an uphill slope.

Effects of the Invention

[0008] According to the starting assist device described in claim 1, the control device engages the first clutch when the vehicle is at a speed equal to or lower than a predetermined speed (including the speed of 0 when the vehicle stops) and the vehicle is on an uphill slope. When the vehicle with the first clutch engaged attempts to reverse on the uphill slope, the wheels rotate in the reverse direction and the output shaft rotates in the reverse direction. The rotation of the output shaft is transmitted to the second shaft via the second gear mechanism and is transmitted to the first shaft and the first gear mechanism via the first clutch. Since the reduction ratio of the second gear mechanism is smaller than the reduction ratio of the first gear mechanism, the second clutch composed of a one-way clutch engages. Here, double meshing occurs, so the reverse rotation of the output shaft can be mechanically prevented without consuming power. As a result, the vehicle does not reverse.

[0009] When starting, when at least one of the motors of the first drive device and the second drive device is started, the output shaft rotates forward and the vehicle starts. In addition to the fact that no braking force acts during starting in the starting assist device, the motor has a large starting torque, so the discomfort during starting can be reduced.

[0010] When the control device disengages the first clutch, which is an engagement clutch, it rotates the first shaft so that the first gear mechanism rotates in the normal direction. This makes it easier to disengage the engaged first clutch, and Since the output shaft can rotate via the first gear mechanism, the acceleration during starting can be improved.

[0012] Claim 2 According to the starting assist device described in, the vehicle can be set to at least a forward mode in which the vehicle moves forward by the forward rotation of the output shaft and a reverse mode in which the vehicle moves backward by the reverse rotation of the output shaft. When the control device is set to a mode other than the forward mode, the first clutch is disengaged. Therefore, in addition to the effect, the function of the mode other than the forward mode can be prevented from being inhibited. 1's In addition to the effect, the function of the mode other than the forward mode can be prevented from being inhibited.

Brief Description of the Drawings

[0014]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

[0015] Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a functional block diagram of a vehicle 10 in one embodiment. The vehicle 10 is equipped with a start assist device 11, a first drive device 12, and a second drive device 13. The vehicle 10 is an automobile.

[0016] The start assist device 11 has a function (hill start assist) to prevent the vehicle 10 from reversing when starting on a slope. The start assist device 11 includes a first shaft 14 connected to the first drive device 12, a second shaft 15 connected to the second drive device 13, an output shaft 16, a first gear mechanism 20 that transmits the torque of the first shaft 14 to the output shaft 16, a second clutch 23, a second gear mechanism 30 that transmits the torque of the second shaft 15 to the output shaft 16, a first clutch 40, and a control device 50.

[0017] The first drive device 12 and the second drive device 13 are devices that output the driving force of the vehicle 10. In this embodiment, the first drive device 12 and the second drive device 13 are motors. The motor is an AC motor such as a wound motor or a cage motor, for example. The first drive device 12 and the second drive device 13 have the same torque characteristics.

[0018] The first shaft 14 and the second shaft 15 are arranged coaxially. The output shaft 16 is arranged parallel to the first shaft 14 and the second shaft 15. In this embodiment, the first shaft 14 is arranged coaxially with the output shaft of the first drive device 12 and is coupled to the output shaft of the first drive device 12. The second shaft 15 is arranged coaxially with the output shaft of the second drive device 13 and is coupled to the output shaft of the second drive device 13. The first shaft 14 and the second shaft 15 are arranged so as to be relatively rotatable with respect to each other via a pilot bearing (not shown).

[0019] The mechanical output of the output shaft 16 is transmitted to a differential device 18 disposed at the center of the axle 17. The axle 17 is arranged parallel to the output shaft 16. The differential device 18 distributes the driving force to the left and right axles 17. It is of course possible to provide a limiting device for limiting the operation of the differential device 18. Wheels 19 are respectively arranged at both ends of the axle 17. In addition to the wheels 19, the vehicle 10 is provided with a plurality of wheels (not shown), and travels by the rotational drive of the axle 17 and the wheels 19.

[0020] The first gear mechanism 20 is a mechanism that decelerates the rotation of the first shaft 14 and transmits it to the output shaft 16. The first gear mechanism 20 includes a first gear 21 coupled to the first shaft 14, and a second gear 22 that is coupled to the output shaft 16 or idles the output shaft 16 by a second clutch 23. The second gear 22 meshes with the first gear 21. The first gear mechanism 20 is set to a reduction ratio by the meshing of the first gear 21 and the second gear 22.

[0021] The second clutch 23 is a one-way clutch that transmits the forward rotation of the first gear mechanism 20 to the output shaft 16. In the present embodiment, the second clutch 23 is disposed on the output shaft 16 and is interposed between the output shaft 16 and the second gear 22. Forward rotation refers to the direction in which mechanical elements such as gears rotate when the vehicle 10 moves forward, and reverse rotation refers to the rotation direction of mechanical elements when the vehicle 10 moves backward.

[0022] In the relative rotation between the output shaft 16 and the second gear 22, the second clutch 23 transmits the forward rotation of the second gear 22 to the output shaft 16, while blocking the transmission of the forward rotation from the output shaft 16 to the second gear 22. Also, in the relative rotation between the output shaft 16 and the second gear 22, the second clutch 23 blocks the transmission of the reverse rotation of the second gear 22 to the output shaft 16, while transmitting the reverse rotation of the output shaft 16 to the second gear 22.

[0023] The second gear mechanism 30 is a mechanism that decelerates the rotation of the second shaft 15 and transmits it to the output shaft 16. The second gear mechanism 30 includes a third gear 31 coupled to the second shaft 15 and a fourth gear 32 coupled to the output shaft 16 and meshing with the third gear 31. The second drive device 13 can always transmit power to the output shaft 16 via the second gear mechanism 30. The second gear mechanism 30 is set to a reduction ratio smaller than the reduction ratio of the first gear mechanism 20 by the meshing of the third gear 31 and the fourth gear 32. The first gear mechanism 20 is a transmission path for low speed, and the second gear mechanism 30 is a transmission path for high speed.

[0024] A fifth gear 33 coupled to the output shaft 16 meshes with a sixth gear 34 coupled to the differential device 18. The fifth gear 33 and the sixth gear 34 transmit the power of the output shaft 16 to the axle 17 via the differential device 18.

[0025] The first clutch 40 transmits and cuts off the power between the first shaft 14 and the second shaft 15. In the present embodiment, the first clutch 40 is an engagement clutch. Examples of the engagement clutch include a gear clutch, a two-tooth clutch, and a jaw clutch. However, the first clutch 40 is not limited to this, and it is of course possible to adopt other clutches such as friction clutches other than the engagement clutch or to incorporate a synchromesh.

[0026] The control device 50 is a device for controlling the first drive device 12, the second drive device 13, and the first clutch 40. The control device 50 includes a CPU which is an arithmetic processing device, a ROM which stores programs, arithmetic parameters, etc. used by the CPU, and a RAM (none of which are shown in the figure) which temporarily stores parameters that change appropriately during the execution of the CPU.

[0027] The control device 50 disconnects and connects the first clutch 40 using the actuator 41. The actuator 41 axially moves the sleeve 43 via the spring 42. The axial restoring force of the spring 42 is applied to the sleeve 43 in conjunction with the operation of the actuator 41.

[0028] An inverter 61 and an inverter 62 are connected to a control device 50 via a CAN communication line 60. The inverter 61 is connected to a first drive device 12, and the inverter 62 is connected to a second drive device 13. The control device 50 controls the first drive device 12 and the second drive device 13 using the inverters 61 and 62.

[0029] A first rotation sensor 63, a second rotation sensor 64, a vehicle speed sensor 65, an acceleration sensor 66, an accelerator pedal sensor 67, a brake pedal sensor 68, a sleeve position sensor 69, a shift lever 70, other input / output devices 71, and a power storage device 72 are connected to the control device 50.

[0030] The first rotation sensor 63 is a device for detecting the rotation speed of the first drive device 12. The first rotation sensor 63 includes an output circuit (not shown) that detects the rotation speed of the first shaft 14, processes the detection result, and outputs it to the control device 50. The second rotation sensor 64 is a device for detecting the rotation speed of the second drive device 13. The second rotation sensor 64 includes an output circuit (not shown) that detects the rotation speed of the second shaft 15, processes the detection result, and outputs it to the control device 50.

[0031] The control device 50 controls the torque of the first drive device 12 by detecting and feeding back the current flowing through the inverter 61, and controls the torque of the second drive device 13 by detecting and feeding back the current flowing through the inverter 62. The control device 50 also controls the rotation speed of the first drive device 12 by detecting and feeding back the rotation speed of the first shaft 14 by the first rotation sensor 63, and controls the rotation speed of the second drive device 13 by detecting and feeding back the rotation speed of the second shaft 15 by the second rotation sensor 64.

[0032] The vehicle speed sensor 65 is a device for detecting the speed of the vehicle 10 (hereinafter referred to as "vehicle speed"). The vehicle speed sensor 65 detects the rotational speed of the output shaft 16, calculates the vehicle speed in consideration of the reduction ratios of the fifth gear 33, the sixth gear 34, and the differential device 18, the size of the wheels 19, etc., and includes an output circuit (not shown) that outputs to the control device 50. This is not limited thereto, and the vehicle speed sensor 65 may detect the rotational speed of the axle 17 and calculate the vehicle speed in consideration of the size of the wheels 19, etc.

[0033] The acceleration sensor 66 detects the acceleration generated in the vehicle 10 and includes an output circuit (not shown) that processes the detection result and outputs it to the control device 50. Examples of the acceleration sensor 66 include a sensor that detects three-axis acceleration and a gyro sensor.

[0034] The accelerator pedal sensor 67 detects the depression amount of the accelerator pedal (not shown) by the driver, and includes an output circuit (not shown) that processes the detection result and outputs it to the control device 50. The output of the accelerator pedal sensor 67 is proportional to the driving force (torque / radius of the wheel 19) required by the driver.

[0035] The total torque required by the driver, that is, the torque required by the output shaft 16 (hereinafter referred to as "target torque") is determined by the detection result of the accelerator pedal sensor 67 (operation amount of the accelerator pedal) and the detection result of the vehicle speed sensor 65 (vehicle speed). In the present embodiment, the target torque is expressed as the torque of the output shaft 16 in consideration of the reduction ratios of the fifth gear 33, the sixth gear 34, and the differential device 18 and the radius of the wheels 19.

[0036] The brake pedal sensor 68 detects the depression amount of the brake pedal (not shown) by the driver, and includes an output circuit (not shown) that processes the detection result and outputs it to the control device 50. The braking device of the vehicle 10 operates based on the brake pedal force. Examples of the braking device include those that utilize the braking torque of a motor (such as reverse-phase braking or single-phase braking), hydraulic brakes, and electromagnetic brakes.

[0037] The sleeve position sensor 69 includes an output circuit (not shown) that detects the position of the sleeve 43 of the first clutch 40, processes the detection result, and outputs it to the control device 50. Based on the detection result of the sleeve position sensor 69, the control device 50 detects whether the first clutch 40 is engaged or disengaged.

[0038] The shift lever 70 is an input device for the driver to select a shift position. Examples of the shift positions selected by the shift lever 70 include a forward mode for moving the vehicle 10 forward, a reverse mode for moving the vehicle 10 backward, a neutral mode, and a stop mode. In the neutral mode, the inverters 61, 62 stop their outputs.

[0039] Examples of other input / output devices 71 include a notification device that notifies the driver by sound, light, etc. that the hill start assist is functioning, and a navigation device. The navigation device detects that the vehicle 10 is located on an uphill slope and outputs it to the control device 50.

[0040] The power storage device 72 is a battery, a capacitor, etc. that supplies power to the inverters 61, 62, the control device 50, etc. The power storage device 72 is supplied with external power, and is also supplied with and charged with the generated power when the first drive device 12 and the second drive device 13 are regeneratively braked.

[0041] Figure 2 is a functional block diagram of the control device 50. The control device 50 includes a determination unit 51 and a control unit 56. The determination unit 51 determines whether to exert the hill start assist function and outputs it to the control unit 56. The control unit 56 controls the first drive device 12 and the first clutch 40 based on the determination result of the determination unit 51.

[0042] The mode determination unit 52 determines whether the vehicle 10 is in the forward mode based on the input from the shift lever 70. The stop determination unit 53 determines whether the vehicle 10 is stopped (vehicle speed V = 0) based on the detection result of the vehicle speed sensor 65. The vehicle speed determination unit 54 determines whether the vehicle 10 is at a speed equal to or lower than a predetermined speed V0 (V0≠0) and whether the vehicle 10 is at a speed equal to or higher than a predetermined speed V1 (V1 > V0) based on the detection result of the vehicle speed sensor 65.

[0043] The gradient determination unit 55 calculates, based on the detection result of the acceleration sensor 66, the pitch angle, which is, for example, the angle of inclination of the vehicle 10 in the pitch direction, as the gradient of the road surface, and determines whether the vehicle 10 is located on an uphill slope based on the gradient. The gradient determination unit 55 may also determine whether the vehicle 10 is located on an uphill slope based on the detection result of the navigation device.

[0044] The drive control unit 57 controls the first drive device 12. The first clutch control unit 58 operates the actuator 41 to engage or disengage the first clutch 40. The brake control unit 59 controls a braking device (not shown) of the vehicle 10 based on the brake pedal force and other signals.

[0045] Figure 3 is a chart showing the combinations of operations of the first drive device 12, the second drive device 13, and the first clutch 40 in the forward mode and the reverse mode. In Figure 3, the first drive device 12, the second drive device 13, and the first clutch 40 that operate in each mode are indicated by ×.

[0046] The control device 50 performs control to set to any one of the first mode, the second A mode, the second B mode, the third mode, and the fourth mode according to the target torque in the forward mode based on a map stored in the ROM. The control device 50 performs control to operate the second drive device 13 in the reverse mode.

[0047] In the first mode, the control device 50 disengages the first clutch 40, de-energizes the second drive device 13, and performs power running control on the first drive device 12. The first mode is used during starting or low-speed driving. Since the torque of the first drive device 12 is output to the output shaft 16 via the first gear mechanism 20 having a larger reduction ratio than the second gear mechanism 30, it is possible to obtain a large driving torque from low speed and perform a powerful start and low-speed driving.

[0048] In the second mode (second A and second B modes), the control device 50 performs power running control on the second drive device 13. Since the torque of the second drive device 13 is output to the output shaft 16 via the second gear mechanism 30 having a smaller reduction ratio than the first gear mechanism 20, it is possible to perform fuel-efficient high-speed driving. The second clutch 23 composed of a one-way clutch does not transmit the forward rotation of the output shaft 16 to the second gear 22. Therefore, in the second A mode in which the first clutch 40 is disengaged, when the second drive device 13 drives the output shaft 16, the drag loss by the first gear mechanism 20 and the first drive device 12 can be suppressed.

[0049] In the second B mode, since the first clutch 40 is engaged, the first drive device 12 rotates with it. At this time, when there is a request to switch to the fourth mode in which the first drive device 12 and the second drive device 13 are driven by engaging the first clutch 40, it can be smoothly switched to the fourth mode. Also, by de-energizing the first drive device 12 in the second mode, the power consumption in the second mode can be reduced accordingly.

[0050] Note that the first drive device 12 may be energized in the second mode. Since the second clutch 23 is arranged on the output shaft 16, when the rotational speed of the second gear 22 driven by the first drive device 12 is smaller than the rotational speed of the fourth gear 32 (output shaft 16) driven by the second drive device 13, the second clutch 23 disengages and the driving force of the first drive device 12 is not transmitted to the output shaft 16.

[0051] In the second mode, when the first drive device 12 is energized to increase the rotational speed of the first drive device 12, the time required to match the rotational speeds of the first shaft 14 and the second shaft 15 can be shortened, so that the first clutch 40 can be easily engaged. Therefore, the switching time from the second mode to the fourth mode can be shortened.

[0052] In the third mode, the control device 50 refers to a map with the first clutch 40 disengaged and performs power running control on the first drive device 12 and the second drive device 13. When the rotational speed of the second gear 22 driven by the first drive device 12 is higher than the rotational speed of the fourth gear 32 (output shaft 16) driven by the second drive device 13, the second clutch 23 composed of a one-way clutch is engaged, so that the driving forces of the first drive device 12 and the second drive device 13 are transmitted to the output shaft 16.

[0053] On the other hand, when the rotational speed of the second gear 22 driven by the first drive device 12 is lower than the rotational speed of the fourth gear 32 (output shaft 16) driven by the second drive device 13, the second clutch 23 is disengaged, so that the driving force of the second drive device 13 is transmitted to the output shaft 16. As described above, since the second clutch 23 composed of a one-way clutch is arranged on the output shaft 16, the state where the first drive device 12 and the second drive device 13 drive the output shaft 16 and the state where the second drive device 13 drives the output shaft 16 can be switched smoothly.

[0054] In the fourth mode, the control device 50 performs power running control on the first drive device 12 and the second drive device 13 with the first clutch 40 engaged. In the fourth mode, since the output shaft 16 is always driven by the first drive device 12 and the second drive device 13, the torque output to the output shaft 16 can be increased. In particular, since both the first drive device 12 and the second drive device 13 drive the second gear mechanism 30 of the high-speed transmission path, sufficient driving torque can be obtained even at high speed, enabling acceleration.

[0055] In the reverse mode, the control device 50 performs torque control to rotate the second drive device 13 in the reverse direction with the first clutch 40 disengaged. Since the torque of the reverse rotation of the second drive device 13 is transmitted to the output shaft 16 via the second gear mechanism 30, the vehicle 10 can be reversed. The reverse rotation of the output shaft 16 is transmitted to the first gear mechanism 20 and the first shaft 14 via the second clutch 23, but since the first clutch 40 is disengaged, the second shaft 15 is not affected by the rotation of the first shaft 14.

[0056] Referring to FIGS. 4 and 5, the start assist process (hereinafter referred to as "assist process") will be described. FIG. 4 is a flowchart of the assist process in the first embodiment. The assist process is a process for preventing the vehicle 10 from reversing during a hill start. The assist process is repeatedly executed (for example, at intervals of 0.2 seconds) by the control device 50 while the power is on.

[0057] In the assist process shown in FIG. 4, the control device 50 determines whether it is in the forward mode (S1). When it is in the forward mode (S1: Yes), it determines whether the vehicle 10 is stopped (vehicle speed V = 0) (S2). When it is not in the forward mode (S1: No), the process of S6 is executed.

[0058] When the vehicle 10 is stopped in the process of S2 (S2: Yes), the control device 50 determines whether the vehicle 10 is located on an uphill slope (S3). When the vehicle 10 is not stopped (S2: No), the process of S6 is executed.

[0059] When the vehicle 10 is located on an uphill slope in the process of S3 (S3: Yes), the control device 50 operates the actuator 41 to engage the first clutch 40 (S4), turns off the brake by the brake control unit 59 (S5), and turns on the assist flag (S6). When the vehicle 10 is not on an uphill slope (S3: No), the process of S7 is executed. Since the first clutch 40 is a meshing clutch, after the first clutch 40 is engaged, the first clutch 40 can be connected without applying an operating force to the first clutch 40.

[0060] When the vehicle 10 stopped with the first clutch 40 engaged on the uphill slope, since the first drive device 12 and the second drive device 13 are not operating, when the driver releases the brake pedal, the vehicle 10 tries to reverse on the uphill slope. Then the wheels 19 rotate in the reverse direction, and the output shaft 16 rotates in the reverse direction. The rotation of the output shaft 16 is transmitted to the second shaft 15 via the second gear mechanism 30, and is transmitted to the first shaft 14 and the first gear mechanism 20 via the first clutch 40. Since the reduction ratio of the second gear mechanism 30 is smaller than the reduction ratio of the first gear mechanism 20, the second clutch 23 engages. Here, double meshing occurs, so the reverse rotation of the output shaft 16 can be mechanically prevented. Therefore, even if the braking device (not shown) is turned off or the driver releases the brake pedal, the vehicle 10 will not reverse.

[0061] When stopping the vehicle 10, since the first drive device 12 and the second drive device 13, which are motors, do not consume power, the power consumption by the first drive device 12 and the second drive device 13 can be reduced. Further, when stopping the vehicle 10, since there is no need to pass current through the first drive device 12 and the second drive device 13, overheating of a specific circuit of the motor can be prevented. Therefore, the performance degradation of the motor due to overheating when stopping the vehicle 10 can be reduced.

[0062] In the vehicle 10 stopped with the first clutch 40 engaged on the uphill slope, when a mode other than the forward mode is input by operating the shift lever 70 (S1: No), or when the accelerator pedal is depressed and a vehicle speed is generated (S2: No), the control device 50 determines whether the assist flag is ON (S7). When the assist flag is OFF (S7: No), since the first clutch 40 is disengaged, this assist process is terminated.

[0063] When the driver steps on the accelerator pedal (S2: No), at least one of the first drive device 12 and the second drive device 13 is driven and the vehicle 10 starts. Since the first clutch 40 is engaged at the start, both the first shaft 14 and the second shaft 15 rotate. When the assist flag is ON (S7: Yes), in the process of S5, the brake device (not shown) is turned off. Since the stop of the vehicle 10 is due to the engagement of the second clutch 23, the braking force of the brake device does not act on the starting assist device 11 during starting. Therefore, the discomfort of being dragged by the braking force of the brake device can be reduced during starting. Furthermore, since the first drive device 12 and the second drive device 13 which are motors have a large starting torque, the driving feeling during starting can be improved.

[0064] When the assist flag is ON (S7: Yes), the control device 50 determines whether the vehicle 10 is at a predetermined vehicle speed V1 (V1≠0) or higher (S8). When the vehicle 10 is at a predetermined vehicle speed V1 or higher (S8: Yes), the control device 50 drives the first drive device 12 to rotate the first shaft 14 in the forward direction (S9), operates the actuator 41 to disengage the first clutch 40 (S10), and turns off the assist flag (S11).

[0065] In the process of S9, the control device 50 rotates the first shaft 14 so that the first gear mechanism 20 rotates forward. Thereby, the differential rotation between the second shaft 15 and the first shaft 14 can be reduced via the first clutch 40. Therefore, it is easier to disengage the first clutch 40 in the process of S10. Furthermore, if the first drive device 12 is continuously driven after the first clutch 40 is disengaged, torque is transmitted to the output shaft 16 via the first gear mechanism 20, so that the acceleration during starting can be improved.

[0066] When the speed of the vehicle 10 starting on the uphill is V1 (V1≠0) or higher (S8: Yes), the control device 50 disengages the first clutch 40 (S10), so that when the vehicle speed is less than V1 after the vehicle 10 starts, the operation switching of the first clutch 40 can be prevented. After the first clutch 40 is disengaged, the output shaft 16 can be rotated via the first gear mechanism 20 whose reduction ratio is larger than that of the second gear mechanism 30. Therefore, the acceleration of the vehicle 10 can be improved.

[0067] When the vehicle 10 stopped with the first clutch 40 engaged on an uphill slope is set to a mode other than the forward mode (S1: No), the control device 50 disengages the first clutch 40 when the vehicle speed V1 is reached or higher, so that the functions of modes other than the forward mode can be prevented from being inhibited.

[0068] With reference to FIG. 5, the assist process in the second embodiment will be described. The same parts as those in the assist process in the first embodiment are denoted by the same reference numerals, and the following description thereof will be omitted. FIG. 5 is a flowchart of the assist process in the second embodiment.

[0069] In the assist process shown in FIG. 5, the control device 50 determines whether or not it is in the forward mode (S12). When it is in the forward mode (S12: Yes), it determines whether or not the accelerator pedal is depressed (S13). When it is not in the forward mode (S12: No), the process of S7 is executed.

[0070] When the accelerator pedal is not depressed in the process of S13 (S13: No), the control device 50 determines whether or not the vehicle 10 is at a predetermined vehicle speed V0 (V0≠0, V0<V1) or lower (S14). When the accelerator pedal is depressed (S13: Yes), the process of S7 is executed.

[0071] When the accelerator pedal is depressed (S13: Yes), since the brake pedal force is zero, the brake control unit 59 disengages the brake device (not shown) based on the brake pedal force. When the assist flag is ON (S7: Yes), the first clutch 40 is engaged (S4), and the reverse rotation of the output shaft 16 is mechanically prevented. Therefore, even when the driving force of the motor is small or the motor is not driving with the brake device disengaged, the vehicle 10 can be prevented from moving backward on the uphill slope.

[0072] In the process of S14, when the vehicle speed is equal to or lower than a predetermined vehicle speed V0 (S14: Yes), the control device 50 determines whether the vehicle 10 is located on an uphill slope (S3). When the vehicle speed exceeds the predetermined value V0 (S14: No), the process of S7 is executed.

[0073] In the process of S3, when the vehicle 10 is located on an uphill slope (S3: Yes), the control device 50 operates the actuator 41 to engage the first clutch 40 (S4) and turns on the assist flag (S6). When the vehicle 10 is not on an uphill slope (S3: No), the process of S7 is executed.

[0074] When the vehicle 10 decelerates to a speed equal to or lower than a predetermined speed V0 (V0≠0) (S14: Yes), the control device 50 engages the first clutch 40 when the conditions of S3 are met (S4). Therefore, when the vehicle 10 is traveling on an uphill slope exceeding the predetermined value V0, the first clutch 40 can be prevented from being engaged while ignoring the total torque (target torque) required by the driver. Therefore, the driving feeling when the vehicle 10 is traveling on an uphill slope can be optimized. Furthermore, the first clutch 40 can be made to operate immediately when the vehicle 10 stops.

[0075] As described above, the present invention has been described based on the embodiments. However, it is easily inferred that the present invention is not limited to the above embodiments at all, and various improvements and modifications can be made without departing from the spirit of the present invention.

[0076] In the embodiment, the case where motors with the same torque characteristics are used for the first drive device 12 and the second drive device 13 has been described. However, it is not necessarily limited to this. It is naturally possible to use motors with different torque characteristics. For example, a motor having torque characteristics for low speed is used as the first drive device 12, and a motor having torque characteristics for high speed is used as the second drive device 13.

[0077] In the embodiment, the case where both the first drive device 12 and the second drive device 13 are motors has been described, but it is not necessarily limited to this. It is of course possible to use an engine for either the first drive device 12 or the second drive device 13.

[0078] In the embodiment, in the process of S8 of the assist process, the case where the first drive device 12 is operated to rotate the first shaft 14 in the normal direction before disengaging the first clutch 40 has been described, but it is not necessarily limited to this. It is of course possible to omit the process of S8. This is because the actuator 41 axially moves the sleeve 43 of the first clutch 40 via the spring 42, and the axial restoring force of the spring 42 is applied to the sleeve 43 in conjunction with the operation of the actuator 41. Even if the process of S8 is omitted, when the torque transmitted by the first clutch 40 becomes small, the first clutch 40 is disengaged by the spring 42.

[0079] In the embodiment, the case where the control device 50 performs control to switch to any one of the first mode, the second A mode, the second B mode, the third mode, and the fourth mode based on a map according to information input from the vehicle speed sensor 65, the accelerator pedal sensor 67, etc. has been described, but it is not limited to this. Instead of the vehicle speed, it is of course possible to perform mode switching using the rotational speed or angular velocity of the output shaft 16 or the axle 17. This is because the rotational speed or angular velocity of the output shaft 16 or the axle 17 is proportional to the vehicle speed and is essentially the same. Also, as long as it is a factor proportional to the torque required by the driver, such as the speed of the accelerator pedal (the change speed of the accelerator pedal), it is of course possible to use other factors. It is of course possible to add the detection result of the brake pedal sensor to this factor.

[0080] In the embodiment, the case where no intermediate shaft is arranged between the first shaft 14 and the second shaft 15 and the output shaft 16 has been described, but it is not necessarily limited to this. It is of course possible to provide one or more intermediate shafts, arrange gears on the intermediate shafts respectively, and provide a part of the gear train constituting the first gear mechanism 20 and the second gear mechanism 30 on the intermediate shafts. It is of course possible to arrange the second clutch 23 on the intermediate shaft on which a part of the first gear mechanism 20 is arranged.

[0081] In the embodiment, the case where the first shaft 14 and the second shaft 15 are directly connected to the output shafts of the first driving device 12 and the second driving device 13 has been described, but it is not necessarily limited to this. It is of course possible to interpose a gear, a belt, or the like between the first driving device 12 and the first shaft 14 or between the second driving device 13 and the second shaft 15.

[0082] In the embodiment, the case where the first gear mechanism 20 is arranged separately from the first driving device 12 has been described, but it is of course possible to integrally assemble the first gear mechanism 20 to the first driving device 12 like a geared motor. Similarly, it is of course possible to integrally assemble the second gear mechanism 30 to the second driving device 13.

[0083] In the embodiment, the case where the wheel 19 is attached to the axle 17 arranged in parallel with the output shaft 16 has been described, but it is not necessarily limited to this. For example, it is of course possible to connect a pair of propeller shafts to the differential device 18 and connect the propeller shafts to the axles respectively. Thereby, a four-wheel drive vehicle can be obtained.

Explanation of Reference Numerals

[0084] 10 Vehicle 11 Starting Assist Device 12 First Driving Device 13 Second Driving Device 14 First Shaft 15 Second Shaft 19 Wheel 20 First Gear Mechanism 23 Second Clutch 30 Second Gear Mechanism 40 First clutch 50 Control device 51 Determination unit 56 Control unit

Claims

1. A starting assist device for a vehicle in which power of an output shaft is transmitted to a wheel, a first gear mechanism that transmits the torque of a first shaft to which the torque of a first drive device is transmitted to the output shaft, a second shaft disposed coaxially with the first shaft, and a second gear mechanism that transmits the torque of the second shaft to which the torque of a second drive device is transmitted to the output shaft at a reduction ratio smaller than the reduction ratio of the first gear mechanism, a first clutch that transmits and interrupts power between the first shaft and the second shaft, a second clutch including a one-way clutch that transmits the forward rotation of the first gear mechanism when the vehicle moves forward to the output shaft, and a control device that operates the first clutch, the second gear mechanism inseparably connects the output shaft to the second shaft, at least one of the first drive device and the second drive device is a motor, the first clutch is an engagement clutch, the control device includes a determination unit that determines whether the vehicle decelerates to a predetermined speed V0 or less and is on an uphill slope, and whether the vehicle is at a predetermined speed V1 or more greater than the speed V0, and a control unit that controls the first drive device and the first clutch based on the determination result of the determination unit, the control unit engages the first clutch when the vehicle decelerates to a speed V0 or less and is on an uphill slope, keeps the first clutch engaged when the vehicle stops, and mechanically prevents reverse rotation of the output shaft when the vehicle reverses on the uphill slope, a starting assist device that drives the first drive device to rotate the first shaft forward and disengages the first clutch when the vehicle reaches a speed V1 or more.

2. The vehicle can be set at least to a forward mode in which the vehicle moves forward by the forward rotation of the output shaft and a reverse mode in which the vehicle moves backward by the reverse rotation of the output shaft, The control device according to claim 1, wherein the first clutch is disengaged when the vehicle is set to a mode other than the forward mode.

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