JP4760757B2 - Vehicle drive device - Google Patents

Description

  The present invention belongs to the technical field of a vehicle drive device that drives wheels using two motors.

As a conventional vehicle drive device, one in which two motors are connected to an axle via reducers having different reduction ratios is known (for example, see Patent Document 1).
JP 2005-104215 A

  However, in the above-described prior art, the motor on the side where the reduction ratio (output rotation / input rotation) is large when running at a low speed in the acceleration region uses a motor having torque characteristics for high speeds. There was a problem that drive torque could not be obtained.

  The present invention has been made paying attention to the above problems, and an object of the present invention is to provide a vehicle drive device capable of obtaining a sufficient drive torque particularly in an acceleration range during low-speed traveling.

In order to achieve the above object, the present invention provides:
A first motor and a second motor;
A first reduction gear connected to the first motor by a first shaft;
An axle connected by a first shaft and a second shaft;
A second reducer;
Switchable between a first state in which the second motor and the second shaft are connected and a second state in which the second motor and the first shaft are connected via the second reducer Switching means,
Switching to the first state when the vehicle speed exceeds a predetermined value; switching to the second state when the vehicle speed is equal to or lower than the predetermined value; and drive control means for driving the first and second motors;
It is characterized by providing.

Therefore, in the present invention, the first and second motors are driven in the second state in a low vehicle speed range where the vehicle speed is a predetermined value or less. At this time, the output torque of the second motor is amplified by the second speed reducer and the first speed reducer and output to the axle.
As a result, a sufficient driving torque can be obtained particularly in the acceleration range during low-speed traveling.

  Hereinafter, the best mode for carrying out the present invention will be described based on the first embodiment.

First, the configuration will be described.
FIG. 1 is a schematic configuration diagram showing a rear wheel drive system to which the vehicle drive device of the first embodiment is applied. In the vehicle of the first embodiment, the front wheels (not shown) are driven by an engine, and the rear wheels 1RL, 1RR are shown. Is a hybrid four-wheel drive vehicle driven by two motors M1 and M2.

  The output shaft of the first motor M1 is connected to the first shaft 1. The first shaft 1 is connected to the second shaft 2 via the first speed reducer 3. The first reduction gear 3 is composed of a reduction gear that includes a small-diameter gear 3a provided on the first shaft 1 side and a large-diameter gear 3b provided on the second shaft 2 side.

  The second shaft 2 is connected to a differential gear 6 via a reduction gear 5 composed of a small diameter gear 5a and a large diameter gear 5b. The output side of the differential gear 6 is connected to an axle 7 to which the rear wheels 1RL and 1RR are connected.

  The output shaft 8 of the second motor M2 is provided with a small-diameter gear 4a of the second reduction gear 4 that is a reduction gear. The small diameter gear 4 a is connected to the large diameter gear 4 b of the second reduction gear 4 provided on the third shaft 9.

  Between the first shaft 1 and the third shaft 9, there is provided a first clutch CL1 that connects and disconnects the first shaft 1 and the third shaft. Further, a second clutch CL <b> 2 that connects and disconnects the second shaft 2 and the output shaft 8 is provided between the second shaft 2 and the output shaft 8.

The first clutch CL1 and the second clutch CL2 are connected to the “first state” in which the second motor M2 and the second shaft 2 are connected, and the second motor M2 and the first shaft 1 are connected to the second speed reducer 4. Switching means capable of switching between the “second state” connected via the network.
The 1st axis | shaft 1, the 2nd axis | shaft 2, and the axle shaft 7 are arrange | positioned in parallel, respectively. The third shaft 9 is disposed coaxially with the first shaft 1, and the output shaft 8 is disposed coaxially with the second shaft 2.

  In the first embodiment, a motor having low-speed torque characteristics is used as the first motor M1, and a motor having high-speed torque characteristics is used as the second motor M2. A motor having torque characteristics for low speed is a motor having a torque peak value on the low rotation side. A motor having high-speed torque characteristics is a motor having a torque peak value on the high rotation side.

  The hybrid controller (drive control means) 10 calculates a drive torque command or a regenerative torque command for each of the motors M1 and M2 in accordance with the driver's driving force request and braking force request. In the motor controller 11, the inverter 12 is driven so that the drive currents or regenerative currents of the motors M1 and M2 coincide with the command value, and power is supplied from or regenerated to the battery.

  Further, the hybrid controller 10 controls the engagement / release of both the clutches CL1, CL2 according to the vehicle speed. The hybrid controller 10 is in a “first state” in which the first clutch CL1 is released (OFF) and the second clutch CL2 is engaged (ON) when the vehicle speed is higher than a predetermined value. Further, when the vehicle is traveling at low and medium speeds where the vehicle speed is equal to or lower than a predetermined value, the first clutch CL1 is turned on and the second clutch CL2 is turned off to be in a “second state”.

  The “first state” and the “second state” can be selected by the driver himself by operating the switch 13, but the hybrid controller 10 has two motors M1, M2 and two driving states according to the driving state. Switch state.

  Hereinafter, for simplicity of explanation, the first motor M1 is the motor 1, the second motor M2 is the motor 2, the first shaft 1 is the shaft 1, the second shaft 2 is the shaft 2, the third shaft is the shaft 3, the first The clutch CL1 is the clutch 1, the second clutch CL2 is the clutch 2, the "first state" is the state 1, and the "second state" is the state 2.

[Status switch control processing]
FIG. 2 is a flowchart showing the flow of the state switching control process executed by the hybrid controller 10, and each step will be described below.

  In step S1, a driver requested drive torque is calculated based on the driver's accelerator operation amount and the like, and the process proceeds to step S2.

  In step S2, the driving torque of motor 1 and motor 2 is calculated based on the required driving torque calculated in step S1 and the torque upper limit value that can be output from motor 1 and motor 2, and the process proceeds to step S3.

  In step S3, referring to the map of FIG. 3 from the vehicle speed, the distribution ratio of the motor 1 that is a share ratio of the motor 1 to the motor driving torque is determined, and the process proceeds to step S4. FIG. 3 is a vehicle speed-motor distribution ratio map, and the distribution ratio of the motor 1 is set so as to decrease as the vehicle speed increases.

  In step S4, the distribution ratio of motor 2 is determined from the distribution ratio of motor 1 determined in step S3, and the process proceeds to step S5.

  In step S5, it is determined whether the rotation speed of the motor 2 is equal to or less than a threshold value close to the upper limit value. If YES, the process proceeds to step S6, and if NO, the process proceeds to step S9.

  In step S6, it is determined whether or not the required drive torque calculated in step S1 is equal to or less than a threshold value. If YES, the process proceeds to step S7. If NO, the process proceeds to step S10.

  In step S7, it is determined based on a signal from the switch 13 whether or not the driver has selected “state 2”. If YES, the process moves to step S10, and if NO, the process moves to step S8.

  In step S8, it is determined whether or not the vehicle speed is a predetermined value or less. If YES, the process proceeds to step S10. If NO, the process proceeds to step S9. Here, the “predetermined value” is a threshold value that can be determined as a high vehicle speed range when the vehicle speed exceeds this value, and is set to 60 km / h, for example.

  In step S9, “state 1” is selected. That is, as shown in FIG. 4, the clutch 1 is disengaged, the clutch 2 is engaged, and the process proceeds to return. Here, when transitioning from “state 2” to “state 1”, in order to synchronize the rotation, after releasing the clutch 1, the clutch 2 is slid so that the rotation of the motor 2 coincides with the rotation of the shaft 1. At this time, the clutch 2 is completely engaged.

  In step S10, “state 2” is selected. That is, as shown in FIG. 4, the clutch 1 is engaged, the clutch 2 is released, and the process proceeds to return. Here, when transitioning from “state 1” to “state 2”, in order to synchronize the rotation, after releasing the clutch 2, the clutch 1 is slid so that the rotation of the motor 2 coincides with the rotation of the shaft 2. At this time, the clutch 1 is completely engaged.

Next, the operation of the vehicle drive device according to the first embodiment will be described.
In the high vehicle speed range where the vehicle speed exceeds the predetermined value, the flow proceeds to step S1 → step S2 → step S3 → step S4 → step S5 → step S6 → step S7 → step S8 → step S9 in the flowchart of FIG. “State 1” in which 1 is turned off and clutch 2 is turned on is selected. At this time, the output torque of the motor 1 is transmitted to the axle 7 via the first reduction gear 3 and the reduction gear 5, and the output torque of the motor 2 is transmitted to the axle 7 via the reduction gear 5.

  Here, since the motor 1 has a low-speed torque characteristic and the motor 2 has a high-speed torque characteristic, a sufficient driving torque is applied to the motor 1 and the motor 2 in a high vehicle speed range where the axle 7 is at a high rotation speed. Obtainable.

  In the low and medium vehicle speed range where the vehicle speed is less than or equal to the predetermined value, the flow proceeds from step S1 → step S2 → step S3 → step S4 → step S5 → step S6 → step S7 → step S8 → step S10. “State 2” in which the clutch 2 is turned off is selected. At this time, the output torque of the motor 1 is transmitted to the axle 7 via the first reduction gear 3 and the reduction gear 5, and the output torque of the motor 2 is the second reduction gear 4, the first reduction gear 3, and the reduction gear. 5 is transmitted to the axle 7 via 5.

  That is, in the “state 2”, the output torque of the motor 2 is amplified by the reduction ratio of the second reduction gear 4 and the first reduction gear 3 and transmitted to the axle as compared with the case of the “state 1”. It becomes possible. Therefore, even in the low vehicle speed range, the output torque of the motor 2 having high-speed torque characteristics can be sufficiently increased, and the running performance in the acceleration range can be remarkably improved.

  Here, when “state 2” is selected, the rotational speed of the motor 2 connected to the axle 7 with a high reduction ratio reaches the upper limit of the rotational speed due to the characteristics of the bearing and the motor even in the low vehicle speed range. obtain. On the other hand, in the first embodiment, a rotation speed threshold value for limiting the control range of “state 2” is set to the vehicle speed until reaching the upper limit of rotation, and when exceeding this, the process proceeds from step S5 to step S9. , “State 1” is selected to protect the motor 2 (see FIG. 5).

  In the first embodiment, “state 1” and “state 2” can be selected by the driver's switch operation. When the driver selects “state 2”, the process proceeds from step S7 to step S10. Give priority to driver selection regardless of vehicle speed. On the other hand, even if the driver has selected “state 1”, if the required drive torque exceeds a predetermined value, the process proceeds from step S6 to step S10 to switch to “state 2”.

  That is, when the driver selects “State 2”, the driver requests high acceleration performance. In this case, by maintaining “State 2” regardless of the vehicle speed. Acceleration according to the driver's acceleration request can be obtained. Even when the driver selects “State 1” and travels, if the required driving torque exceeds a predetermined value, the state shifts to “State 2” to meet the acceleration request. Drive torque can be output without delay.

  FIG. 6 is a time chart showing the driving state switching effect of the first embodiment. The vehicle is traveling at a low speed, but “state 1” is selected by the driver's switch operation. Clutch 2 is ON.

  At time t1, since the driver has started to depress the accelerator, the command values of the drive torques of the motors 1 and 2 rise according to the driver request drive torque.

  At time t2, since the driver's required driving torque exceeds the threshold value, the clutch 2 is turned off and the clutch 1 is slid to reduce the rotational speed of the motor 2 in order to shift from “state 1” to “state 2”. Raise.

  At the time t3, since the rotational speeds of the motor 2 and the shaft 1 are synchronized, the clutch 1 is turned on (completely engaged) and the state shifts to “state 2”. As a result, the output torque of the motor 2 is amplified by the second speed reducer 4 and the first speed reducer 3, so that the motor 2 having a high-speed torque characteristic is compared with the case where “state 1” is maintained. The output torque is sufficiently increased, and the running performance in the acceleration range can be improved.

  At time t4, since the rotational speed of the motor 2 has reached the threshold value, the clutch 1 is turned OFF and the rotational speed of the motor 2 is decreased by sliding the clutch 2 in order to shift from “state 2” to “state 1”. Let

  At time t5, since the rotational speeds of the motor 2 and the shaft 2 are synchronized, the clutch 2 is turned on (completely engaged) and the state shifts to “state 1”. Thereby, the over rotation of the motor 2 can be avoided reliably.

Finally, effects of the vehicle drive device of the first embodiment are listed below.
(1) The first motor M1 and the second motor M2, the first speed reducer 3 connected by the first motor M1 and the first shaft 1, and the axle shaft 7 connected by the first speed reducer 3 and the second shaft 2. And the "first state" in which the second speed reducer 4, the second motor M2 and the second shaft 2 are connected, and the second motor M2 and the first shaft 1 are connected via the second speed reducer 4. Switching means (clutch CL1, CL2) capable of switching between the connected “second state” and when the vehicle speed exceeds a predetermined value, it switches to “first state”, and when the vehicle speed is equal to or lower than the predetermined value. Comprises a hybrid controller 10 that switches to the “second state” and drives the first and second motors M1, M2. As a result, a sufficient driving torque can be obtained particularly in the acceleration range during low-speed traveling.

  (2) Since the hybrid controller 10 drives the first and second motors M1 and M2 in the “second state” when the driving demand of the driver exceeds the threshold, the acceleration performance according to the acceleration demand of the driver Can be obtained.

  (3) Since the hybrid controller 10 drives the first and second motors M1, M2 in the “first state” when the rotational speed of the second motor M2 exceeds a threshold value close to the upper limit value, the second motor M2 Problems caused by the M2 rotation speed reaching the upper limit can be reliably avoided.

  (4) A switch 13 for selecting one of “first state” and “second state” is provided by the driver, and the hybrid controller 10 allows the driver to select “second state”. Is a case where the “second state” is maintained even when the vehicle speed exceeds the predetermined value, and the driver's drive request is a threshold value when the driver selects the “first state”. If exceeded, the mode is switched to the “second state”. Thereby, the driving torque according to the driver's acceleration request can be output without delay.

(Other examples)
The best mode for carrying out the present invention has been described based on the first embodiment. However, the specific configuration of the present invention is not limited to the first embodiment and does not depart from the gist of the present invention. Any change in the design of the range is included in the present invention.

  For example, in the first embodiment, a motor having a low speed torque characteristic is used as the first motor and a motor having a high speed torque characteristic is used as the second motor. Even if it is used, the acceleration performance in the acceleration region can be sufficiently enhanced.

It is a schematic block diagram which shows the drive system of the rear wheel to which the vehicle drive device of Example 1 is applied. 4 is a flowchart showing a flow of state switching control processing executed by the hybrid controller 10. It is a vehicle speed-motor distribution ratio map of the 1st motor. It is a clutch fastening table in the state 1 and the state 2. It is a motor torque characteristic figure according to a vehicle speed. 3 is a time chart illustrating a driving state switching effect of the first embodiment.

Explanation of symbols

M1 1st motor
M2 2nd motor
CL1 1st clutch
CL2 2nd clutch
1RL left rear wheel
1RR Right rear wheel 1 1st shaft 2 2nd shaft 3 1st speed reducer 4 2nd speed reducer 5 Reduction gear 6 Differential gear 7 Axle 8 Output shaft 9 3rd shaft 10 Hybrid controller 11 Motor controller 12 Inverter 13 Switch

Claims (4)

A first motor and a second motor;
A first reduction gear connected to the first motor by a first shaft;
An axle connected by a first shaft and a second shaft;
A second reducer;
Switchable between a first state in which the second motor and the second shaft are connected and a second state in which the second motor and the first shaft are connected via the second reducer Switching means,
Switching to the first state when the vehicle speed exceeds a predetermined value; switching to the second state when the vehicle speed is equal to or lower than the predetermined value; and drive control means for driving the first and second motors;
A vehicle drive device comprising: The vehicle drive device according to claim 1,
The vehicle drive device according to claim 1, wherein the drive control means drives the first and second motors in the second state when a driver's drive request exceeds a predetermined value. In the vehicle drive device according to claim 1 or 2,
The vehicle drive device according to claim 1, wherein the drive control means drives the first and second motors in the first state when the rotational speed of the second motor exceeds a threshold value close to an upper limit value. In the vehicle drive device according to any one of claims 1 to 3,
A switch for the driver to select one of the first state and the second state;
When the driver has selected the second state, the drive control means maintains the second state even when the vehicle speed exceeds the predetermined value. When the state is selected and the driver's drive request exceeds the predetermined value, the vehicle drive device is switched to the second state.

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