JP6291170B2 - Vehicle control device - Google Patents

Description

  The present invention relates to a vehicle control device including an oil pump.

  In recent years, idling stop vehicles have been developed in which the engine is automatically stopped and started according to the driving situation. In such an idling stop vehicle, it is necessary to supply hydraulic oil to a hydraulic system such as a transmission mechanism and a friction engagement mechanism even when the engine is stopped. Therefore, many idling stop vehicles are equipped with an electric oil pump driven by an electric motor in addition to an oil pump driven by an engine.

  In recent years, hybrid vehicles including an engine and a traveling motor have been developed. Also in such a hybrid vehicle, the engine is automatically stopped and started according to the driving situation, and it is necessary to supply hydraulic oil to a hydraulic system such as a transmission mechanism and a friction engagement mechanism even when the engine is stopped. Therefore, many hybrid vehicles are equipped with an electric oil pump driven by an electric motor in addition to an oil pump driven by an engine, as in the idling stop vehicle.

  In the idling stop vehicle and the hybrid vehicle as described above, the electric oil pump is driven when the engine is stopped, and the line pressure that is the basic hydraulic pressure of the hydraulic control system is secured (see Patent Document 1).

JP 2011-117333 A

  However, the rotational speed (discharge pressure) of the electric oil pump described in Patent Document 1 is such that the line pressure that decreases with the decrease in the rotational speed (discharge pressure) of the oil pump driven by the engine becomes the predetermined line pressure. Even after returning, the same rotation speed is maintained. Thus, maintaining the rotation speed of the electric oil pump constant leads to an increase in power consumption.

  An object of the present invention is to reliably secure a line pressure while reducing power consumption of an electric oil pump.

  The vehicle control device of the present invention includes a power transmission path that connects an engine and driving wheels, a first oil pump that is driven by a drive system coupled to the power transmission path, and a second that is driven by an electric motor. An oil pump, and a pump control unit that controls the second oil pump. The pump control unit drives the second oil pump when the rotation speed of the first oil pump decreases to a predetermined rotation speed, and decreases the rotation speed of the second oil pump when the rotation speed of the engine becomes zero. .

  In the present invention, the second oil pump is driven when the rotational speed of the first oil pump decreases to a predetermined rotational speed, and the rotational speed of the second oil pump is decreased when the rotational speed of the engine becomes zero. Therefore, it is possible to reliably secure the line pressure while reducing the power consumption of the electric pump.

It is the schematic which shows an example of the power unit mounted in a vehicle. It is the schematic which shows the structure of the control apparatus for vehicles which is one embodiment of this invention. It is a flowchart which shows the procedure of the control mode setting process performed by the control unit. It is explanatory drawing which shows an example of the change state of the engine speed at the time of a control mode setting process being performed, the drive state of an electric pump, and the control mode of an electric pump. It is explanatory drawing which shows another example of the engine speed at the time of execution of a control mode setting process, the drive state of an electric pump, and the change condition of the control mode of an electric pump.

  Hereinafter, an example of an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic diagram showing an example of a power unit 10 mounted on a vehicle. As shown in FIG. 1, the power unit 10 includes an engine 11 and a traveling motor 12 as power sources. The power unit 10 is provided with a continuously variable transmission (transmission mechanism) 13, and the continuously variable transmission 13 is provided with a primary pulley 14 and a secondary pulley 15. The engine 11 is connected to one side of the primary pulley 14 via a torque converter 16. On the other hand, a traveling motor 12 is connected to the other side of the primary pulley 14. A drive wheel output shaft 18 is coupled to the secondary pulley 15 via a fuse clutch 17. Drive wheels 21 are connected to the drive wheel output shaft 18 via a differential mechanism 19 and an axle shaft 20. A motor generator 24 is connected to the crankshaft 22 of the engine 11 via a drive belt 23. The motor generator 24 is a so-called ISG (Integrated Starter Generator) that functions as a generator and an electric motor. The motor generator 24 can be used to start and rotate the crankshaft 22.

  Between the torque converter 16 and the primary pulley 14, an input clutch 30 that is switched between a released state and an engaged state is provided. By switching the input clutch 30 to the released state, the primary pulley 14 and the engine 11 can be disconnected. As a result, the travel mode can be set to the motor travel mode, and the engine 11 can be stopped and only the power of the travel motor 12 can be transmitted to the drive wheels 21. On the other hand, the primary pulley 14 and the engine 11 can be connected by switching the input clutch 30 to the engaged state. As a result, the traveling mode can be set to the parallel traveling mode, and the power of the traveling motor 12 and the engine 11 can be transmitted to the drive wheels 21.

  The continuously variable transmission 13 provided between the traveling motor 12 and the drive wheel 21 has a primary shaft 32 connected to the rotor shaft 31 of the traveling motor 12 and a secondary shaft 33 parallel to the primary shaft 32. ing. A primary pulley 14 is provided on the primary shaft 32, and a primary chamber 34 is defined on the back side of the primary pulley 14. The secondary shaft 33 is provided with a secondary pulley 15, and a secondary chamber 35 is defined on the back side of the secondary pulley 15. Further, a drive chain 36 is wound around the primary pulley 14 and the secondary pulley 15. By adjusting the primary pressure supplied to the primary chamber 34 and the secondary pressure supplied to the secondary chamber 35, the pulley groove width can be changed to change the winding diameter of the drive chain 36. Thereby, continuously variable transmission from the primary shaft 32 to the secondary shaft 33 is possible. As described above, the fuse clutch 17 is provided between the continuously variable transmission 13 and the drive wheel 21. The fuse clutch 17 is a friction clutch that enters a slip state when a set torque is exceeded, and functions as a torque limiter for protecting the continuously variable transmission 13.

  In order to supply hydraulic oil to the hydraulic system such as the continuously variable transmission 13 and the torque converter 16 described above, the power unit 10 is provided with a first oil pump 41 such as a trochoid pump (hereinafter referred to as “mechanical pump 41”). Is provided. Further, the power unit 10 is provided with a valve unit 42 constituted by a plurality of electromagnetic valves and oil passages in order to control the supply destination and pressure of the hydraulic oil. The hydraulic oil discharged from the mechanical pump 41 is supplied to the continuously variable transmission 13, the torque converter 16, and the like through the valve unit 42.

  The mechanical pump 41 includes an outer rotor 43 and an inner rotor 44 incorporated therein. A rotor shaft 45 and a driven sprocket 46 are attached to one end of the inner rotor 44. A drive sprocket 48 is attached to the primary shaft 32 parallel to the rotor shaft 45 via a one-way clutch 47. A chain 49 is wound around the drive sprocket 48 and the driven sprocket 46, and the primary shaft 32 and the inner rotor 44 are connected via a chain mechanism 50. As described above, the mechanical pump 41 is connected to the primary shaft 32 constituting the first power transmission path via the first drive system 51 including the chain mechanism 50. The first power transmission path is a power transmission path that connects the traveling motor 12 and the drive wheels 21, and includes a rotor shaft 31, a primary shaft 32, a secondary shaft 33, a fuse clutch 17, a drive wheel output shaft 18, A differential mechanism 19 and an axle shaft 20 are included.

  A rotor shaft 61 and a driven sprocket 62 are attached to the other end of the inner rotor 44 of the mechanical pump 41. A drive sprocket 66 is attached to a hollow shaft 64 fixed to the pump shell 63 of the torque converter 16 and parallel to the rotor shaft 61 via a one-way clutch 65. A chain 67 is wound around the drive sprocket 66 and the driven sprocket 62, and the hollow shaft 64 and the inner rotor 44 are connected via a chain mechanism 68. As described above, the mechanical pump 41 is connected to the hollow shaft 64 constituting the second power transmission path through the second drive system 69 including the chain mechanism 68. The second power transmission path is a power transmission path that connects the engine 11 and the drive wheel 21, and includes a hollow shaft 64, an input clutch 30, a primary shaft 32, a secondary shaft 33, a fuse clutch 17, and a drive wheel output shaft. 18, a differential mechanism 19, an axle shaft 20, and the like.

  The one-way clutch 47 included in the first drive system 51 transmits power from the primary shaft 32 rotating in the forward rotation direction to the inner rotor 44, while blocking power transmission in the opposite direction. Similarly, the one-way clutch 65 included in the second drive system 69 transmits power to the inner rotor 44 from the hollow shaft 64 rotating in the forward rotation direction, while blocking power transmission in the opposite direction. That is, when the primary shaft 32 rotates faster than the hollow shaft 64, the mechanical pump 41 is driven by the primary shaft 32 on the traveling motor 12 side, while the hollow shaft 64 rotates faster than the primary shaft 32. The mechanical pump 41 is driven by the hollow shaft 64 on the engine 11 side. The forward rotation direction of the primary shaft 32 is the rotation direction of the primary shaft 32 during forward travel. The forward rotation direction of the hollow shaft 64 is the rotation direction of the crankshaft 22 when the engine is operating.

  As described above, the primary shaft 32 and the hollow shaft 64 are connected to the inner rotor 44 of the mechanical pump 41. Thereby, in the parallel traveling mode in which the engine 11 is driven, the mechanical pump 41 can be driven by the engine 11, and the continuously variable transmission 13 and the like can be hydraulically controlled by the hydraulic oil from the mechanical pump 41. Even in the motor travel mode in which the engine 11 is stopped, the mechanical pump 41 can be driven by the primary shaft 32 when the vehicle travels with the primary shaft 32 rotating. Thus, the mechanical pump 41 is an oil pump that is rotationally driven by at least one of the two drive systems coupled to the power transmission path.

  Here, when the vehicle speed falls below a predetermined speed during traveling in the parallel traveling mode, the traveling mode is switched to the motor traveling mode. That is, the input clutch 30 is switched to the released state and the engine 11 is stopped. Thereafter, when the rotational speed of the primary shaft 32 decreases with a decrease in the vehicle speed, the rotational speed (discharge pressure) of the mechanical pump 41 also decreases. When the vehicle stops, the primary shaft 32 also stops and the mechanical pump 41 also stops. However, it is necessary to continue supplying hydraulic oil to the hydraulic system such as the continuously variable transmission 13 even at low vehicle speeds or when stopped.

  Therefore, the vehicle control device 70 should ensure the line pressure that is the basic hydraulic pressure of the hydraulic system even when the vehicle speed decreases or the vehicle stops when the motor travel mode is set. A second oil pump 72 (hereinafter referred to as “electric pump 72”) that is driven to rotate by the electric motor 71 is provided. For example, when the motor travel mode in which the engine 11 is stopped is set, if the rotation speed of the primary shaft 32 decreases with a decrease in the vehicle speed, the rotation speed (discharge pressure) of the mechanical pump 41 also decreases. Therefore, the electric pump 72 is driven so as to supplement the mechanical pump 41. Thereafter, when the rotational speed of the primary shaft 32 exceeds a predetermined value as the vehicle speed increases, the discharge pressure of the mechanical pump 41 is recovered and the electric pump 72 is stopped.

  By the way, a target vehicle state (hereinafter referred to as “target vehicle state”) is set based on various conditions, and various controls are executed to realize the set target vehicle state. For example, when the stop condition and start condition of the engine 11 are satisfied, various controls for stopping or starting the engine 11 are executed. For example, when the stop condition of the engine 11 is satisfied, control such as shutting off the fuel supply to the engine 11 is executed. However, even if the control for stopping the engine 11 is started, the engine speed [rpm] does not immediately become 0 (zero), and the engine speed gradually decreases. However, when the engine speed decreases, the speed [rpm] of the mechanical pump 41 decreases and the line pressure [MPa] may be insufficient. Therefore, the vehicle control device 70 determines whether or not the electric pump 72 needs to be driven when the engine stop condition is satisfied, and when it is determined that the electric pump 72 needs to be driven, The drive of the pump 72 is started. That is, the electric pump 72 is activated. However, always driving the electric pump 72 at a constant rotational speed causes an increase in power consumption.

  Therefore, the vehicle control device 70 executes control mode setting processing for setting the control mode of the electric pump 72 based on the target vehicle state, the current vehicle state, and the like, and drives the electric pump 72 according to the set control mode. . In the present embodiment, three control modes are prepared as control modes for the electric pump 72. Specifically, a first control mode in which the first target rotational speed is set, a second control mode in which the second target rotational speed is set, and a third control mode in which the third target rotational speed is set are prepared. Yes. Here, the first target rotational speed is higher than the second target rotational speed. That is, the target rotational speed in the first control mode is higher than the target rotational speed in the second control mode. Therefore, in the following description, the first control mode is referred to as “HIGH mode”, and the second control mode is referred to as “LOW mode”. Further, the third target rotational speed that is the target rotational speed in the third control mode is 0 (zero). Therefore, in the following description, the third control mode is referred to as “stop mode”.

  Hereinafter, the control mode setting process executed by the vehicle control device 70 will be described. FIG. 2 is a schematic diagram showing a configuration of a vehicle control device 70 according to an embodiment of the present invention. In FIG. 2, the same members as those shown in FIG. 1 are denoted by the same reference numerals and description thereof is omitted. As shown in FIG. 2, the vehicle control device 70 is provided with a control unit 73 that functions as at least a pump control unit and a travel motor control unit. The control unit 73 includes a wheel speed sensor 74 that detects the rotation speed of the drive wheel 21, a motor rotation sensor 76 that detects the rotation speed of the rotor 75 included in the traveling motor 12, and an engine speed that detects the rotation speed of the engine 11. A sensor 77 or the like is connected. The engine speed sensor 77 detects the speed of the crankshaft 22 of the engine 11 and outputs a signal indicating the detection result to the control unit 73. An inverter 79 is connected to the stator 78 of the traveling motor 12, and the control unit 73 controls the traveling motor 12 through the inverter 79. The control unit 73 includes a CPU that calculates control signals and the like, a ROM that stores control programs, arithmetic expressions and map data, and a RAM that temporarily stores data.

  Next, the procedure of the control mode setting process executed by the control unit 73 will be described with reference to FIGS. For ease of understanding, FIG. 3 does not affect the vehicle speed, that is, when the vehicle speed is 0 (zero) or very close to it, or when the vehicle speed changes in synchronization with the engine speed change. The operation of is shown.

  In the control unit 73, steps S1 to S7 shown in FIG. 4 are always executed. In steps S1 to S3, a determination is made regarding the conditions for setting the control mode of the electric pump 72 shown in FIG. In steps S4 to S6, the control mode of the electric pump 72 shown in FIG. 2 is set based on the determination results in steps S1 to S3. In step S7, the electric pump 72 shown in FIG. 2 is driven according to the control mode set in steps S4 to S6. Hereinafter, each step shown in FIG. 4 will be described in detail.

  In step S1 shown in FIG. 4, it is determined whether or not the stop condition of the engine 11 shown in FIG. 2 is satisfied. For example, the accelerator opening is one of the engine stop conditions, and when the accelerator opening is 0 (zero), at least one of the engine stop conditions is satisfied. If it is determined in step S1 shown in FIG. 4 that the engine stop condition is not satisfied, it is determined that the driving of the electric pump 72 is unnecessary, and the process proceeds to step S4. If “mode” is set and it is determined that all the engine stop conditions including the accelerator opening are satisfied, the process proceeds to step S2 shown in FIG.

  In step S2 shown in FIG. 4, it is determined whether or not driving of the electric pump 72 shown in FIG. 2 is necessary. When the vehicle speed is 0 (zero) or very close to 0 (zero), or the vehicle speed changes in synchronization with the change of the engine speed, the line pressure is reduced when the speed of the mechanical pump 41 is reduced as the engine speed is reduced. descend. Therefore, it is necessary to drive the electric pump 72 in order to ensure the line pressure. In other words, when the vehicle speed is sufficiently high or the engine speed is high and the speed of the mechanical pump 41 exceeds a predetermined value, the discharge pressure of the mechanical pump 41 is sufficiently high, and the line pressure required only by the mechanical pump 41 is obtained. It is secured. Therefore, in step S <b> 2 shown in FIG. 4, it is determined whether the electric pump 72 needs to be driven based on the rotational speed of the mechanical pump 41. Specifically, when the rotational speed of the mechanical pump 41 exceeds a predetermined rotational speed, it is determined that the driving of the electric pump 72 is unnecessary, and the process proceeds to step S4, where “stop mode” is set as the control mode of the electric pump 72. Is done. On the other hand, when the rotational speed of the mechanical pump 41 is equal to or lower than the predetermined rotational speed, it is determined that the electric pump 72 needs to be driven, and the process proceeds to step S3. However, the necessity of driving the electric pump 72 may be determined based on the engine speed.

  In step S3 shown in FIG. 4, it is determined whether or not the engine speed is 0 (zero). If the engine speed is not 0 (zero), the engine speed may increase immediately thereafter. For example, the accelerator pedal may be depressed by the driver, and the accelerator opening may increase. That is, the engine stop condition may become unsatisfactory. In other words, there is a possibility that the engine start condition and the driving motor driving condition are satisfied, and the mode is shifted to the parallel driving mode or the motor driving mode. In this case, it is necessary to transmit the power of the engine 11 and the traveling motor 12 shown in FIG. 2 to the drive wheels 21, and it is necessary to supply hydraulic pressure to the continuously variable transmission 13, the fuse clutch 17, and the like. Therefore, when it is determined in step S3 shown in FIG. 4 that the engine speed is not 0 (zero), the process proceeds to step S5 shown in FIG. 4 and “HIGH mode” is set as the control mode of the electric pump 72. The

  On the other hand, when the engine speed is 0 (zero), it is sufficient to secure only a supplementary pressure for preparing for the next travel. Therefore, if it is determined in step S3 shown in FIG. 4 that the engine speed is 0 (zero), the process proceeds to step S6 shown in FIG. 4 and “LOW mode” is set as the control mode of the electric pump 72. The

  As described above, when the control mode of the electric pump 72 is set in step S4, S5 or S6 shown in FIG. 4, the process proceeds to step S7 shown in FIG. 4, and the electric pump 72 is driven in the set control mode. Is done.

  Refer to FIG. 3 again. When the engine speed decreases to the predetermined speed (r1), the rotational speed of the mechanical pump 41 decreases accordingly, and the control mode of the electric pump 72 is set as described above, and the electric pump 72 is set in the set control mode. Is driven. Here, the engine speed that has decreased to the predetermined speed (r1) does not immediately become 0 (zero), but gradually decreases thereafter. Therefore, it is determined that the engine speed is not 0 (zero) in step S3 shown in FIG. 4 until the engine speed decreases from the predetermined speed (r1) to 0 (zero). The Therefore, the HIGH mode is set in step S5. Then, in step S7, the electric pump 72 is driven in the HIGH mode. That is, the electric pump 72 continues to be driven in the HIGH mode until the engine speed decreases to the predetermined speed (r1) and becomes 0 (zero).

  Thereafter, as shown in FIG. 3, when the engine speed becomes 0 (zero), it is determined in step S3 shown in FIG. 4 that the engine speed is 0 (zero). Therefore, the LOW mode is set in step S6. Then, in step S7, the electric pump 72 is driven in the LOW mode. That is, when the engine speed becomes 0 (zero), the electric pump 72 is driven in the LOW mode. In other words, the control mode of the electric pump 72 is switched from the HIGH mode to the LOW mode.

  That is, the control unit 73 which is a pump control unit drives the electric pump 72 in the HIGH mode when the engine speed decreases to a predetermined speed (r1) and the mechanical pump 41 decreases accordingly. The electric pump 72 driven in the HIGH mode rotates at the first target rotation speed that is the target rotation speed in the HIGH mode. Next, when the engine speed becomes 0 (zero), the control unit 73 switches the control mode of the electric pump 72 from the HIGH mode to the LOW mode, and drives the electric pump 72 in the LOW mode. The electric pump 72 driven in the LOW mode rotates at the second target rotation speed that is the target rotation speed in the LOW mode. Here, as described above, the first target rotational speed is higher than the second target rotational speed. That is, the control unit 73 which is a pump control unit drives the electric pump 72 when the rotational speed of the mechanical pump 41 decreases to a predetermined rotational speed, and decreases the rotational speed of the electric pump 72 when the engine rotational speed becomes 0 (zero). Let

  Further, as shown in FIG. 3, while the engine speed is 0 (zero), the control mode of the electric pump 72 is maintained in the LOW mode, and when the engine speed is no longer 0 (zero), HIGH again. Switch to mode. Furthermore, when the engine speed increases to a second predetermined speed (r2) higher than the predetermined speed (r1), and the rotational speed of the mechanical pump 41 increases to the predetermined speed, the electric pump 72 stops. Is done.

  FIG. 5 shows the same preconditions as in FIG. 3, but changes in the drive state of the electric pump 72 and the control modes of the electric pump 72 when the change state of the engine speed is different from the change state shown in FIG. . As shown in FIG. 5, when the engine speed decreases to a predetermined speed (r1), the electric pump 72 is driven in the HIGH mode. The change situation so far is the same as the change situation shown in FIG. However, in the case shown in FIG. 5, the engine speed that has decreased to the predetermined speed (r1) then increases without becoming 0 (zero). In a situation where the engine speed changes as shown in FIG. 5, it is not determined that the engine speed is 0 (zero) in step S3 shown in FIG. 4, and thus the process does not proceed to step S6. . In other words, the control mode of the electric pump 72 is not switched from the HIGH mode to the LOW mode, and the electric pump 72 continues to be driven in the HIGH mode.

  As described above, in vehicle control apparatus 70 according to the present embodiment, electric pump 72 is driven when the engine speed decreases to a predetermined speed (r1). Therefore, even if the rotational speed of the mechanical pump 41 decreases with a decrease in the engine rotational speed, the line pressure is ensured. Further, when the engine speed becomes 0 (zero), the speed of the electric pump 72 is decreased. Therefore, the power consumption of the electric pump 72 is reduced. On the other hand, the rotational speed of the electric pump 72 cannot be decreased until the engine rotational speed becomes 0 (zero). Therefore, even if the engine speed that has decreased below the predetermined speed (r1) starts to increase before it reaches 0 (zero), the line pressure does not become insufficient. In general, according to the vehicle control device 70 according to the present embodiment, it is possible to reliably ensure the line pressure while reducing the power consumption of the electric pump 72.

  It goes without saying that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the invention. For example, in the embodiment, three modes are prepared as the control mode of the electric pump, but the number of control modes may be four or more.

  In the above embodiment, the chain drive type continuously variable transmission is used as the speed change mechanism. However, the present invention is not limited to this, and a belt drive type or traction drive type continuously variable transmission may be used. It may be a planetary gear type or parallel shaft type automatic transmission. Further, the mechanical pump and the electric pump may be an inscribed gear pump or an outer gear pump.

11 Engine 12 Traveling motor 13 Continuously variable transmission (transmission mechanism)
21 Drive wheel 41 Mechanical pump (first oil pump)
51 First Drive System 69 Second Drive System 70 Vehicle Control Device 71 Electric Motor 72 Electric Pump (Second Oil Pump)
73 Control unit (pump control unit, travel motor control unit)

Claims (2)

A power transmission path connecting the engine and the drive wheels;
A first oil pump driven by a drive system connected to the power transmission path;
A second oil pump driven by an electric motor;
A pump control unit for controlling the second oil pump;
Have
As a control mode of the second oil pump, a first control mode in which a first target rotational speed is set and a second control mode in which a second target rotational speed lower than the first target rotational speed is set. Prepared,
The pump control unit drives the second oil pump in the first control mode and drives the second oil pump in the first control mode when the rotation speed of the first oil pump decreases to a predetermined rotation speed. After that, when the engine speed becomes zero, the second oil pump is driven in the second control mode, and the engine speed is increased after the second oil pump is driven in the first control mode. A vehicle control device that continues to drive the second oil pump in the first control mode when it turns . The vehicle control device according to claim 1,
The pump control unit maintains the control mode of the second oil pump in the second control mode while the engine speed is zero.
Vehicle control device.

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