JP2016175478A - Hybrid vehicle and method of controlling the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hybrid vehicle that can improve a regeneration efficiency at the time of a high speed travel, that can be easily converted from an existing vehicle, and that can improve safety performance.SOLUTION: The hybrid vehicle connects a propeller shaft 25 and a rotation shaft 32 of a motor generator 33 via a speed reduction mechanism 30 where the rotation shaft of the motor generator is provided as an input shaft and the propeller shaft is provided as an output shaft, and includes a second power steering pump 45. A control device 80, when a pressure of power steering fluid 44 supplied by a first power steering pump becomes lower than a set value, controls the speed reduction mechanism and causes the motor generator to be operated so that a first state where the motor generator and the propeller shaft are connected via the speed reduction mechanism is cancelled to be switched to a second state where the motor generator and the second power steering pump are connected via the speed reduction mechanism.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a hybrid vehicle and a control method therefor, and more particularly to a hybrid vehicle that can improve regeneration efficiency during high-speed traveling and can be easily converted from an existing vehicle and a control method therefor.

  In recent years, a hybrid vehicle (hereinafter referred to as “HEV”) including a hybrid system having an engine and a motor generator that are controlled in combination according to the driving state of the vehicle has attracted attention from the viewpoint of improving fuel efficiency and environmental measures. Yes. In the HEV, when the vehicle is accelerated or started, the driving force is assisted by the motor generator, while regenerative power generation is performed by the motor generator during inertia traveling or braking (see, for example, Patent Document 1).

  In such a so-called parallel HEV, the motor generator is normally connected to the drive system of the vehicle from the engine side of the transmission for shifting the rotational power of the engine. For this reason, when the HEV is traveling at high speed (for example, 50 to 90 km / h), the transmission is shifted to a high speed, so that the regenerative braking torque in the motor generator is reduced and the power generation is increased. There is a problem that it is difficult to improve the efficiency of regenerative power generation because it is out of the efficiency point.

  Moreover, since it is necessary to change the layout of the powertrain components of the existing vehicle in order to arrange the motor generator, there is a problem that it is not easy to convert the existing vehicle to HEV. .

  In the case of a conventional HEV, the pressure of the power steering fluid supplied from the power steering pump to the steering unit, for example, when an abnormality occurs in the hydraulic circuit connecting the power steering pump driven by the diesel engine and the steering unit. Becomes lower than a preset value, it becomes difficult for the steering unit to perform steering assist. In this case, the safety performance of the hybrid vehicle is degraded.

JP 2002-238105 A

  An object of the present invention is to provide a hybrid vehicle that can improve the regenerative efficiency during high-speed running than before, can be easily diverted from an existing vehicle, and can improve safety performance, and a control method therefor. .

In order to achieve the above object, a hybrid vehicle of the present invention includes a propeller shaft that connects a transmission connected to a diesel engine and a differential that drives wheels, a hybrid system including the diesel engine and a motor generator, and a power steering fluid. In a hybrid vehicle, comprising: a steering unit that performs steering assist using a vehicle; a first power steering pump that is driven by the diesel engine to supply power steering fluid to the steering unit; and a control device. The rotation shaft of the motor generator is connected to the rotation shaft of the motor generator through the reduction mechanism having the rotation shaft of the motor generator as the input shaft and the propeller shaft as the output shaft, and the second power steering pump is further connected The reduction mechanism includes a first state in which the motor generator and the propeller shaft are connected via the reduction mechanism, and a second state in which the motor generator and the second power steering pump are connected via the reduction mechanism. The control device is configured to switch the second state when the pressure of the power steering fluid supplied by the first power steering pump falls below a preset value. The speed reduction mechanism is controlled so as to switch to a state and the motor generator is operated, and the second power steering pump is driven by the operation of the motor generator in the second state to supply power steering fluid to the steering unit It is characterized by this.

  According to the hybrid vehicle of the present invention, since the propeller shaft and the rotation shaft of the motor generator are connected via the speed reduction mechanism, the regenerative braking torque of the motor generator is increased during inertia traveling during high speed traveling. Regeneration efficiency can be improved. Moreover, since the regeneration efficiency at the time of high-speed driving can be improved simply by newly attaching a speed reduction mechanism to the propeller shaft of an existing vehicle, conversion from the existing vehicle can be performed more easily than in the past.

  Further, even when the pressure of the power steering fluid supplied by the first power steering pump driven by the diesel engine is lower than the set value, the motor generator and the second power steering pump are connected via the speed reduction mechanism. When the motor generator operates, the second power steering pump connected to the motor generator via the speed reduction mechanism can be driven to supply the power steering fluid to the steering unit to perform steering assist. Thereby, the safety performance of the hybrid vehicle can be improved.

  In order to achieve the above object, a hybrid vehicle control method of the present invention includes a propeller shaft that couples a transmission connected to a diesel engine and a differential driving a wheel, and a hybrid system including the diesel engine and a motor generator. A hybrid vehicle control method comprising: a steering unit that performs steering assist using power steering fluid; and a first power steering pump that is driven by the diesel engine and supplies power steering fluid to the steering unit. The propeller shaft and the rotation axis of the motor generator are connected via a reduction mechanism having the rotation axis of the motor generator as an input shaft and the propeller shaft as an output shaft. The hybrid vehicle further includes a second power steering pump, and the speed reduction mechanism includes a first state in which the motor generator and the propeller shaft are connected via the speed reduction mechanism, the motor generator and the second power steering pump. And a second state where the second power steering pump is driven by the operation of the motor generator in the second state to supply power steering fluid to the steering unit. When the pressure of the power steering fluid supplied by the first power steering pump drops below a preset value, the speed reduction mechanism is controlled so that the first state is released and the second state is switched. Including operating the motor generator. It is an butterfly.

According to the hybrid vehicle control method of the present invention, since the propeller shaft and the rotation shaft of the motor generator are connected via the speed reduction mechanism, the regenerative braking torque of the motor generator is reduced during inertia traveling during high speed traveling. Increase the regeneration efficiency. Moreover, since the regeneration efficiency at the time of high-speed driving can be improved simply by newly attaching a speed reduction mechanism to the propeller shaft of an existing vehicle, conversion from the existing vehicle can be performed more easily than in the past. Further, even when the pressure of the power steering fluid supplied by the first power steering pump driven by the diesel engine is lower than the set value, the motor generator and the second power steering pump are connected via the speed reduction mechanism. When the motor generator operates, the second power steering pump connected to the motor generator via the speed reduction mechanism can be driven to supply the power steering fluid to the steering unit to perform steering assist. Thereby, the safety performance of the hybrid vehicle can be improved.

  According to the hybrid vehicle and its control method of the present invention, it is possible to improve the regenerative efficiency at the time of high-speed traveling, and it is easy to divert from an existing vehicle, and the safety performance can be improved.

It is a block diagram of the hybrid vehicle which consists of embodiment of this invention. It is the schematic diagram which expanded the deceleration mechanism vicinity of a hybrid vehicle. It is an example of the flowchart of the control processing at the time of abnormality which a control apparatus performs.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a hybrid vehicle according to an embodiment of the present invention. This hybrid vehicle (hereinafter referred to as “HEV”) is a large vehicle such as a bus or a truck, and includes a hybrid system having a diesel engine 10 and a motor generator 33 that are controlled in combination according to the driving state of the vehicle. Yes.

  In the diesel engine 10, the crankshaft 13 is rotationally driven by thermal energy generated by the combustion of fuel in a plurality (six in this example) of cylinders 12 formed in the engine body 11. The rotational power of the crankshaft 13 is transmitted to the transmission 20 through the fluid coupling 14 and the wet multi-plate clutch 15. A dry clutch may be used instead of the fluid coupling 14 and the wet multi-plate clutch 15.

  The transmission 20 uses an AMT that automatically shifts gears to a target gear determined based on the HEV operating state and preset map data. The transmission 20 includes a main transmission mechanism 21 capable of shifting input rotational power in a plurality of stages, and a sub-transmission mechanism capable of shifting rotational power transmitted from the main transmission mechanism 21 into two stages, a low speed stage and a high speed stage. 22.

  The rotational power changed by the transmission 20 is transmitted to the differential 26 through the propeller shaft 25 connected to the output shaft 23, and is distributed as a driving force to a pair of driving wheels 27 made of double tires.

  The motor generator 33 is electrically connected to the battery 35 through the inverter 34.

  The diesel engine 10 and the motor generator 33 are controlled by a control device 80. Specifically, at the time of HEV start or acceleration, the motor generator 33 assists at least a part of the driving force, while at the time of inertial running or braking, the motor generator 33 performs regenerative power generation, and surplus The battery 35 is charged by converting kinetic energy into electric power.

  Further, the control device 80 executes auto-cruise when the user turns on the auto-cruise operation switch during HEV traveling. In this auto-cruise, the control device 80 performs high-efficiency operation control for operating the diesel engine 10 in a predetermined high-efficiency region, and idling stop control for stopping operation of the diesel engine 10 by stopping fuel supply to the diesel engine 10. Are alternately executed, so that the HEV speed is controlled to be within a predetermined range without an accelerator operation.

  In such HEV, the propeller shaft 25 and the rotating shaft 32 of the motor generator 33 are connected via a speed reduction mechanism 30. The speed reduction mechanism 30 uses the rotating shaft 32 of the motor generator 33 as an input shaft and the propeller shaft 25 as an output shaft. That is, in the speed reduction mechanism 30, the speed reduction ratio (Nm / Np), which is the ratio of the rotation speed Np of the propeller shaft 25 to the rotation speed Nm of the motor generator 33, is greater than 1.0. Note that this reduction ratio may be set to either fixed or variable.

  Next, the HEV power soaring system will be described. The power steering system is a system that assists HEV steering. Specifically, the power steering system includes various hydraulic circuits (first hydraulic circuit 43, second hydraulic circuit) through which the first power steering pump 40, the second power steering pump 45, the double check valve 49, and the power steering fluids 44, 48, 51 flow. 47 and a main hydraulic circuit 50), an accumulator 52, a steering unit 53, and a pressure sensor 55.

  The first hydraulic circuit 43 communicates the first power steering pump 40 and the double check valve 49. The second hydraulic circuit 47 communicates the second power steering pump 45 and the double check valve 49. Note that the upstream end of the first hydraulic circuit 43 upstream of the first power steering pump 40 and the upstream end of the second hydraulic circuit 47 upstream of the second power steering pump 45 are reservoirs for storing the power steering fluids 44 and 48. It is connected to a tank (not shown). The main hydraulic circuit 50 communicates the double check valve 49 and the steering unit 53. Further, the passage of the main hydraulic circuit 50 is branched and connected to the accumulator 52.

  The first power steering pump 40 is connected to the diesel engine 10 and is driven by the diesel engine 10 to pump the power steering fluid 44. Specifically, the drive shaft 41 of the first power steering pump 40 is connected to the crankshaft 13 of the diesel engine 10 via a V-belt 42 or a gear. The rotational power of the crankshaft 13 is transmitted to the drive shaft 41 via the V-belt 42 or a gear to rotate the drive shaft 41. In this way, the first power steering pump 40 is driven by the diesel engine 10.

  FIG. 2A and FIG. 2B are schematic views in which the vicinity of the HEV reduction mechanism 30 is enlarged. The drive shaft 46 of the second power steering pump 45 is connected to some of the gears 110 of the plurality of gears 112 of the speed reduction mechanism 30.

  Here, as shown in FIG. 2A, the plurality of gears 112 of the speed reduction mechanism 30 according to the present embodiment are in a first state in which the motor generator 33 and the propeller shaft 25 are connected via the speed reduction mechanism 30; As shown in FIG. 2B, the motor generator 33 and the second power steering pump 45 are configured to be able to switch between a second state in which the motor generator 33 and the second power steering pump 45 are connected via the speed reduction mechanism 30.

Thereby, when the control device 80 controls the speed reduction mechanism 30 so as to be in the first state, the power 115 of the propeller shaft 25 is transmitted to the motor generator 33. Further, when the control device 80 drives the motor generator 33 by the battery 35 in the first state, the power 115 of the motor generator 33 is transmitted to the propeller shaft 25. On the other hand, when the control device 80 controls the speed reduction mechanism 30 so that the first state is released and switched to the second state, when the control device 80 drives the motor generator 33 by the battery 35, the motor generator 33 The power 115 is transmitted to the second power steering pump 45 via the speed reduction mechanism 30. Thereby, the second power steering pump 45 is driven to pump the power steering fluid 48.

  In the present embodiment, among the plurality of gears 112 of the speed reduction mechanism 30, the gear 110 to which the drive shaft 46 of the second power steering pump 45 is connected is a case where the diesel engine 10 is stopped during HEV traveling. Even if it exists, it is also a gear which can be rotated by receiving the power 115 of the rotating propeller shaft 25. That is, the gear 110 is a power transmission path for transmitting the power 115 of the propeller shaft 25 to the second power steering pump 45 even when the diesel engine 10 is stopped during HEV traveling.

  Specifically, even when the diesel engine 10 is stopped during the execution of the auto-cruise mode, the propeller shaft 25 connected to the drive wheels 27 via the differential 26 rotates while the drive wheels 27 are rotating. doing. Of the plurality of gears 112 of the speed reduction mechanism 30, at least some of the gears 110 can be rotated by transmitting the power 115 (specifically, rotational power) of the propeller shaft 25 to other gears. It is connected to the propeller shaft 25 via. Therefore, the second power steering pump 45 is driven by the rotating gear 110 (that is, the power transmission path) and pumps the power steering fluid 48 even when the diesel engine 10 is stopped while the HEV is running. Can do.

  The set discharge pressure of the power steering fluid 48 of the second power steering pump 45 is set to be smaller than the setting discharge pressure of the power steering fluid 44 of the first power steering pump 40. Specifically, the second power steering pump 45 is provided with a relief valve. By adjusting the relief valve, the set discharge pressure of the second power steering pump 45 is smaller than the set discharge pressure of the first power steering pump 40. The value has been adjusted.

  As shown in FIG. 1, the double check valve 49 allows the power steering fluids 44 and 48 to flow from the first power steering pump 40 and the second power steering pump 45 to the steering unit 53, and from the first power steering pump 40 to the second power steering pump 40. This is a valve that suppresses the flow of the power steering fluid 44 to the pump 45 and the flow of the power steering fluid 48 from the second power steering pump 45 to the first power steering pump 40. Further, the double check valve 49 preferentially passes the higher pressure of the power steering fluids 44 and 48 supplied from the first power steering pump 40 and the second power steering pump 45 to the steering unit 53 via the main hydraulic circuit 50. It is also a valve to derive.

  The accumulator 52 accumulates the power steering fluid 51 (= 44, 48) via the double check valve 49, that is, the power steering fluid 51 supplied from the first power steering pump 40 and the second power steering pump 45, and the accumulated power steering. Fluid 51 is supplied to steering unit 53 via main hydraulic circuit 50. The configuration of the accumulator 52 is not limited to this. For example, the accumulator 52 has a power steering fluid 51 (= 44 or 44) supplied from only one of the first power steering pump 40 and the second power steering pump 45. 48) may be configured to accumulate.

  The steering unit 53 is an apparatus that assists the steering of the steering 54 by using the supplied power steering fluid 51. If it has such a function, the specific structure of the steering unit 53 will not be specifically limited, A well-known steering unit can be applied. In the present embodiment, a steering unit including a hydraulic power cylinder is used as an example of the steering unit 53.

  The pressure sensor 55 detects the pressure of the power steering fluid supplied by the first power steering pump 40 and transmits the detection result to the control device 80. Specifically, the pressure sensor 55 according to the present embodiment detects the pressure of the power steering fluid 44 of the first hydraulic circuit 43 as an example of the pressure of the power steering fluid supplied by the first power steering pump 40.

  The normal operation of the HEV power steering system described above is as follows. First, when the diesel engine 10 is operating while the HEV is running, the first power steering pump 40 is driven by the diesel engine 10 to pump the power steering fluid 44. Further, the second power steering pump 45 also feeds the power steering fluid 48 by being driven by the gear 110 of the speed reduction mechanism 30 rotating by being connected to the propeller shaft 25 while the HEV is running.

  In this case, as described above, the set discharge pressure of the second power steering pump 45 is set smaller than the set discharge pressure of the first power steering pump 40, and the double check valve 49 has the first power steering pump 40 and the second power steering pump. Since the higher pressure of the power steering fluids 44, 48 supplied from 45 is preferentially led to the steering unit 53, the power steering fluid 48 pumped by the second power steering pump 45 is not supplied to the steering unit 53. Then, the power steering fluid 44, 51 in which the power steering fluid 44 pumped by the first power steering pump 40 and the power steering fluid 51 accumulated in the accumulator 52 merge is supplied.

  When the diesel engine 10 is stopped during inertia traveling or braking during traveling in the HEV auto cruise mode, the pumping of the power steering fluid 44 by the first power steering pump 40 is stopped. On the other hand, even if the diesel engine 10 is stopped during HEV traveling, the propeller shaft 25 continues to rotate as the drive wheels 27 rotate, so the gear 110 of the speed reduction mechanism 30 connected to the propeller shaft 25 rotates. ing. Therefore, the second power steering pump 45 driven by the rotating gear 110 of the speed reduction mechanism 30 can pump the power steering fluid 48 even when the diesel engine 10 is stopped during HEV traveling. . As a result, the power steering fluid 48, 51 in which the power steering fluid 48 pumped by the second power steering pump 45 and the power steering fluid 51 accumulated in the accumulator 52 merge is supplied to the steering unit 53. The operation of the HEV power steering system during normal operation is as described above.

  In addition, the HEV control device 80 performs the following when the pressure of the power steering fluid supplied by the first power steering pump 40 detected by the pressure sensor 55 is lower than a preset value (that is, when there is an abnormality). The abnormal time control process described is executed. FIG. 3 is an example of a flowchart of the abnormal time control process. The CPU of the control device 80 repeatedly executes this flowchart at a predetermined cycle. It is assumed that the speed reduction mechanism 30 is controlled to be in the first state at the first start time of this flowchart.

  In step S10, the control device 80 determines whether or not the pressure of the power steering fluid 44 detected by the pressure sensor 55 is lower than a preset set value. In addition, what is necessary is just to obtain | require an appropriate value for this setting value beforehand by experiment, simulation, etc., and to set it to a memory | storage part (for example, ROM).

When it is determined in step S10 that the pressure of the power steering fluid 44 is lower than the set value (Yes), the control device 80 controls the speed reduction mechanism 30 to release the first state and switch to the second state, and The motor generator 33 is controlled so that the motor generator 33 is operated by 35 (step S20). Step S20
When the motor generator 33 operates, the second power steering pump 45 (second P / S pump) connected to the motor generator 33 via the speed reduction mechanism 30 is driven to supply the power steering fluid 51 to the steering unit 53. After step S20, the control device 80 ends the execution of the flowchart.

  When it determines with No by step S10, the control apparatus 80 controls the deceleration mechanism 30 so that it may switch to a 1st state, and stops the operation | movement of the motor generator 33 by the battery 35, and is 2nd by the motor generator 33. The drive of the power steering pump 45 is stopped (step S30). After step S30, the control device 80 ends the execution of the flowchart.

  According to the HEV described above, the propeller shaft 25 and the rotating shaft 32 of the motor generator 33 are connected via the speed reduction mechanism 30, so that the regenerative braking torque of the motor generator 33 regardless of the gear stage of the transmission 20. Can be increased by the speed reduction mechanism 30, so that the regeneration efficiency can be improved. In addition, this configuration can be realized simply by newly installing the speed reduction mechanism 30 on the propeller shaft 25 of the existing vehicle. Therefore, the change of the layout of the powertrain component can be very small. More easily.

  Further, according to this HEV, even when the pressure of the power steering fluid 44 supplied by the first power steering pump 40 falls below the set value, the motor generator 33 and the second power steering pump 45 are connected via the speed reduction mechanism 30. The second power steering pump 45 connected to the motor generator 33 is driven via the speed reduction mechanism 30 by supplying the power steering fluid 51 to the steering unit 53 when the motor generator 33 is operated in the connected second state. Can do. Thereby, since steering assist can be performed, the safety performance of HEV can be improved.

  Further, according to this HEV, even when the diesel engine 10 is stopped during traveling, the pressure is fed from the second power steering pump 45 driven by the gear 110 (power transmission path) of the rotating reduction mechanism 30. The power steering fluid 48 thus supplied can be supplied to the steering unit 53 to assist steering. Thereby, the diesel engine 10 can be stopped without stopping the steering assist during traveling, and the fuel consumption can be improved.

  Further, since the diesel engine 10 can be stopped without stopping the steering assist during the HEV traveling as described above, for example, when the diesel engine 10 is operated at a low speed and a low load in order to perform the steering assist during the traveling. In comparison, PM (particulate matter) in exhaust is effectively deposited on exhaust purification devices such as DPD (Diesel Particulate Diffuser) and DPF (Diesel Particulate Filter). Can be suppressed. Thereby, the fuel consumption required for regeneration of the exhaust emission control device can be suppressed. Also in this point, according to this HEV, a fuel consumption can be improved effectively.

  Since the HEV includes an accumulator 52, the power steering fluid 44 of the first power steering pump 40 is supplied to the steering unit 53, and the power steering fluid 48 of the second power steering pump 45 is supplied to the steering unit 53. When the state is switched, the pressure of the power steering fluids 44, 48, 51 supplied to the steering unit 53 can be prevented from greatly fluctuating. Thereby, steering assist can be performed effectively.

Further, since the HEV includes the double check valve 49, the flow of the power steering fluid 44 from the first power steering pump 40 to the second power steering pump 45 can be suppressed, and the first power steering pump 45 to the first power steering pump 45 The flow of the power steering fluid 48 to the power steering pump 40 can also be suppressed.

  Further, the double check valve 49 is configured to preferentially lead out the higher pressure of the power steering fluids 44 and 48 supplied from the first power steering pump 40 and the second power steering pump 45 to the steering unit 53, Further, since the set discharge pressure of the second power steering pump 45 is set lower than the set discharge pressure of the first power steering pump 40, while the first power steering pump 40 supplies the power steering fluid 44 to the steering unit 53. The supply of the power steering fluid 48 from the second power steering pump 45 to the steering unit 53 can be stopped. When the supply of the power steering fluid 44 from the first power steering pump 40 to the steering unit 53 stops, the second power steering pump Power steering from 45 to steering unit 53 It is possible to start supplying the Rude 48.

(Modification)
In addition, HEV is good also as a structure which alert | reports abnormality further, when the pressure of the power steering fluid 44 which the 1st power steering pump 40 supplies falls from a setting value. Specifically, in this case, an abnormality notifying device for notifying the user of the abnormality is arranged in the HEV driver's seat. The specific configuration of the abnormality notification device is not particularly limited, but in this modification, as an example, an abnormality notification device that displays abnormality content on a display is used. In this case, for example, in step S20 of FIG. 3, the control device 80 further displays an abnormality indicating that the pressure of the power steering fluid 44 is lower than the set value on the display of the abnormality notification device in addition to the control processing of step S20 described above. Let

  According to this configuration, even when the pressure of the power steering fluid 44 supplied by the first power steering pump 40 is lower than the set value, the steering assist can be performed and the abnormality notification device notifies the user of the abnormality. Therefore, the user can detect the HEV abnormality at an early stage and repair the HEV at an early stage. Thereby, the safety performance of HEV can be improved more.

(HEV control method)
The HEV control method according to the present embodiment is executed by the control device 80 described above. Specifically, the control method according to the present embodiment decelerates the first state to be released and switched to the second state when the pressure of the power steering fluid 44 supplied by the first power steering pump 40 falls below a set value. Step S20 (FIG. 3) which controls the mechanism 30 and operates the motor generator 33 is characterized. According to this control method, the same effect as that of the HEV described above, that is, the regeneration efficiency during high-speed traveling can be improved, the diversion from the existing vehicle is easy, and the safety performance of the HEV can be improved. The effect that it is possible can be produced.

DESCRIPTION OF SYMBOLS 10 Diesel engine 20 Transmission 25 Propeller shaft 26 Differential 27 Drive wheel 30 Deceleration mechanism 32 Rotating shaft 33 Motor generator 40 1st power steering pump 44, 48, 51 Power steering fluid 45 2nd power steering pump 49 Double check valve 52 Accumulator 53 Steering unit 55 Pressure sensor 110 gear (power transmission path)

Claims (2)

A propeller shaft that couples a transmission connected to a diesel engine and a differential that drives wheels; a hybrid system having the diesel engine and a motor generator; a steering unit that performs steering assist using power steering fluid; and the diesel engine In a hybrid vehicle comprising: a first power steering pump that is driven by the first power steering pump to supply power steering fluid to the steering unit;
Connecting the propeller shaft and the rotation axis of the motor generator via a reduction mechanism having the rotation axis of the motor generator as an input axis and the propeller shaft as an output axis;
A second power steering pump;
The reduction mechanism includes a first state in which the motor generator and the propeller shaft are connected via the reduction mechanism, and a second state in which the motor generator and the second power steering pump are connected via the reduction mechanism. Is configured to switch,
When the power steering fluid pressure supplied from the first power steering pump drops below a preset set value, the control device releases the first state and switches to the second state. Control and operate the motor generator,
The hybrid vehicle, wherein the second power steering pump is driven by the operation of the motor generator in the second state to supply power steering fluid to the steering unit. A propeller shaft that couples a transmission connected to a diesel engine and a differential that drives wheels; a hybrid system having the diesel engine and a motor generator; a steering unit that performs steering assist using power steering fluid; and the diesel engine In a control method of a hybrid vehicle comprising: a first power steering pump that is driven by and supplies a power steering fluid to the steering unit;
The hybrid vehicle connects the propeller shaft and the rotation axis of the motor generator via a reduction mechanism having the rotation axis of the motor generator as an input shaft and the propeller shaft as an output shaft,
The hybrid vehicle further includes a second power steering pump,
The reduction mechanism includes a first state in which the motor generator and the propeller shaft are connected via the reduction mechanism, and a second state in which the motor generator and the second power steering pump are connected via the reduction mechanism. Is configured to switch,
The second power steering pump is driven by operation of the motor generator in the second state to supply power steering fluid to the steering unit;
When the pressure of the power steering fluid supplied by the first power steering pump drops below a preset value, the motor is controlled to control the speed reduction mechanism so that the first state is released and switched to the second state. A method for controlling a hybrid vehicle, comprising the step of operating a generator.

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