JP2016175495A - Hybrid vehicle and control method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hybrid vehicle and a control method therefor such that while regeneration efficiency in a high speed travel is improved as compared with the conventional art, a fuel consumption is reduced without stopping a steering assist in an auto-cruising mode, and further a chance to start a diesel engine due to a pressure drop in an air tank is reduced to improve fuel economy.SOLUTION: A hybrid vehicle comprises a speed reduction mechanism 30 which connects a propeller shaft 25 to a rotary shaft 32 of a motor generator 33 and a driving shaft 46 of a second power steering pump 45 respectively, and a switching device which switches a supply source for a power steering fluid 51 from a first power steering pump 40 to the second power steering pump 45, and a controller 80 is configured to perform control to operate an engine brake and also to forcibly operate an unloader valve 62 when pressure pt drops below a pressure determination value pc during speed reduction in an inertial travel.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a hybrid vehicle and a control method thereof, and more specifically, reduces fuel consumption without stopping steering assist in an auto-cruise mode while improving regeneration efficiency during high-speed traveling as compared with the conventional vehicle, The present invention relates to a hybrid vehicle and a control method therefor, which improve the fuel efficiency by reducing the chance of starting a diesel engine accompanying a decrease in air tank pressure.

  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.

  Further, 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 order to solve such a problem, the inventor uses a propeller shaft of a vehicle and a rotation shaft of a motor generator via a reduction mechanism having the rotation shaft of the motor generator as an input shaft and the propeller shaft as an output shaft. Invented to connect.

  Furthermore, the inventor focused on the fuel consumption in the auto cruise mode in order to improve the fuel efficiency of the newly devised HEV, and more specifically to improve the fuel efficiency of large vehicles such as HEV buses and trucks. .

  In the auto-cruise mode, based on the map information including the gradient and distance of the travel path to be traveled and the HEV vehicle weight, the engine travels with the driving force of the engine, and the assist with the driving force of both the engine and the motor generator. The vehicle speed is maintained at the target speed by appropriately selecting traveling, motor traveling that travels with the driving force of the motor generator, and inertia traveling that does not apply the driving force of the engine and the motor generator.

  However, in large vehicles such as buses and trucks, hydraulic steering units are used as steering units (power steering) to assist the driver's steering from the viewpoint of output, steering performance, and reliability. During this time, it is necessary to always supply power steering fluid to the hydraulic steering unit from a power steering pump that is driven by transmission of the driving force of the engine. Therefore, there is a problem in that the fuel consumption cannot be reduced because the engine cannot be stopped during the motor running or the inertia running.

  Also, in large vehicles, pneumatic foot brakes and air suspensions are installed, and the pressure inside the air tank is below the threshold during traveling, so the air compressor is driven by the driving force of the diesel engine, There is also a problem that compressed air needs to be supplied to the air tank.

JP 2002-238105 A

  The object of the present invention is to improve the regenerative efficiency during high-speed running than before, reduce the fuel consumption without stopping the steering assist in the auto cruise mode, and further start the diesel engine due to the pressure drop of the air tank It is an object of the present invention to provide a hybrid vehicle and a method for controlling the same that can improve the fuel efficiency by reducing the chance of the vehicle.

  A hybrid vehicle of the present invention that achieves the above object includes a transmission connected to a diesel engine via a clutch and a propeller shaft that couples a differential that drives a drive wheel, a hybrid system including the diesel engine and a motor generator, A first power steering pump coupled to the diesel engine, a steering unit for assisting steering steering using the power steering fluid supplied from the first power steering pump, an air compressor coupled to the diesel engine, When an air tank that accumulates compressed air supplied from an air compressor, a pneumatic device that drives using compressed air supplied from the air tank, and the pressure of the air tank exceeds a preset upper limit pressure An unloader valve for stopping supply of compressed air from the air compressor to the air tank and starting supply of compressed air from the air compressor to the air tank when the pressure falls below a preset lower limit pressure; and the motor generator A regenerative brake that regenerates the engine, an engine brake that applies the rotational drag of the diesel engine to the propeller shaft, a map information acquisition device that acquires map information, a vehicle weight acquisition device that acquires vehicle weight, and a vehicle speed In a hybrid vehicle including a vehicle speed acquisition device, a pressure acquisition device for acquiring the pressure, and a control device, the propeller shaft and the rotation shaft of the motor generator are used as the input shaft. And a speed reduction mechanism for connecting the propeller shaft as an output shaft; Supply of power steering fluid supplied to the steering unit when the second power steering pump connected to the propeller shaft via the speed reduction mechanism and the first power steering pump stop with the stop of the diesel engine A switching device for switching the power source from the first power steering pump to the second power steering pump, and an operation for the unloader valve for forcibly operating the unloader valve to start the supply of compressed air from the air compressor to the air tank And the control device does not transmit the driving force of the diesel engine and the motor generator to the propeller shaft when an auto-cruise mode for maintaining the vehicle speed within a preset target speed range is set. Based on the map information and the vehicle weight In addition to performing control to stop the diesel engine by stopping fuel injection and stopping the diesel engine during the inertial traveling, the inertial traveling during the inertial traveling is stopped. While the vehicle is decelerating, when the pressure falls below the pressure judgment value set above the lower limit pressure and less than the upper limit pressure, the clutch is engaged and the engine brake is operated, and the unloader The unloader valve is actuated by a valve actuating device, and control for starting the supply of compressed air from the air compressor to the air tank is performed.

  Further, the hybrid vehicle control method of the present invention that achieves the above object, when the auto cruise mode is set, the driving force transmitted from the diesel engine to the propeller shaft via the clutch and transmission, and Any one of the engine running, the assist running, and the motor running that travels with one of the driving forces transmitted from the motor generator to the propeller shaft via the speed reduction mechanism, and the diesel engine is stopped and the diesel engine and the Inertia running that does not transmit the driving force of the motor generator to the propeller shaft is selected on the basis of map information and vehicle weight in a timely manner to automatically run while maintaining the vehicle speed within a preset target speed range. If you choose to run, put the clutch in the disengaged state In addition to stopping the diesel engine, the second power steering pump is driven by the rotational power transmitted from the propeller shaft via the speed reduction mechanism instead of the first power steering pump stopped by the stop of the diesel engine. A control method for a hybrid vehicle that supplies power steering fluid to a steering unit, wherein the pressure of an air tank to which compressed air is supplied from an air compressor driven by the diesel engine while decelerating during inertial running is as follows: The unloader valve is set to exceed the lower limit pressure at which compressed air starts to be supplied from the air compressor to the air tank, and the unloader valve is set to be lower than the upper limit pressure at which supply of compressed air from the air compressor to the air tank is stopped. When the pressure is below the threshold value, Supplying compressed air from the air compressor to the air tank by operating the engine brake that applies the rotational drag of the diesel engine to the propeller shaft with the latch connected, and forcibly operating the unloader valve Is a method characterized by starting.

  According to the hybrid vehicle and its control method of the present invention, the regenerative efficiency during high-speed traveling can be improved by connecting the rotating shaft of the motor generator and the propeller shaft via the speed reduction mechanism.

  In addition, the second power steering pump is connected to the propeller shaft via a speed reduction mechanism, and the power steering fluid supply source when the driving of the first power steering pump is stopped is switched to the second power steering pump, thereby driving the first power steering pump. Even if the engine stops, the supply of power steering fluid to the steering unit is always maintained, so that it is possible to avoid stopping the steering assist.

  In addition, during inertial driving in the auto cruise mode, the clutch is disengaged and the fuel injection is stopped to stop the diesel engine and the idling stop state. Can be reduced.

  In addition, when decelerating during inertial driving, when the air tank pressure falls below a preset pressure judgment value, the clutch is engaged and the engine brake is activated and the unloader valve is forced. Since the compressed air from the air compressor to the air tank is started to operate, even if the diesel engine is stopped during coasting, the air tank pressure is prevented from falling below the lower limit pressure. The opportunity to drive the air compressor can be reduced by driving the diesel engine that consumes the air.

  As a result, in addition to the effect of reducing fuel consumption by stopping the diesel engine during auto-cruise mode, maintaining the air tank pressure above a certain level can reduce the opportunity to start the diesel engine due to the air tank pressure drop. Therefore, fuel consumption can be improved.

It is a block diagram of the hybrid vehicle which consists of embodiment of this invention. It is a block diagram which shows the vehicle-mounted network and control signal line of FIG. It is a flowchart explaining the control method of the hybrid vehicle which consists of embodiment of this invention. It is explanatory drawing which illustrated the relationship with a vehicle speed, an engine torque, a motor generator torque, the charge condition of a battery, and an altitude at the time of drive | working on a steeply descending slope road in the auto cruise mode. It is explanatory drawing which illustrated the relationship with the vehicle speed, an engine torque, a motor generator torque, the charge condition of a battery, and an altitude at the time of drive | working on a gentle downhill road in the auto cruise mode.

  Embodiments of the present invention will be described below with reference to the drawings. 1 and 2 show a hybrid vehicle according to an embodiment of the present invention. In addition, the dashed-dotted line of FIG. 2 has shown the vehicle-mounted network and the control signal line.

  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. Further, the HEV uses a power steering fluid 51 to assist the steering of the steering 54 and a power steering system having a steering unit 53 and an air supply to operate a pneumatic device using compressed air 65 accumulated in an air tank 64. A system and a brake system that applies braking force by a plurality of brakes are provided. Further, the HEV is configured to execute the auto cruise mode when the auto cruise operation switch 81 is turned on by the driver in the control device 80.

  First, the HEV hybrid system will be described. 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 (hereinafter referred to as the 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, the diesel engine 10 uses the engine speed Ne detected by the speed sensor 86 and the accelerator pedal depression amount detected by the accelerator opening sensor 92 to inject fuel into the cylinder 12 and the injection timing. Is adjusted. Further, the motor generator 33 adjusts the frequency of the inverter 34 and the current value between the battery 35 and the motor generator 33 according to the state of charge (SOC) of the battery 35, and the motor generator 33 when the HEV starts or accelerates. While assisting at least a part of the driving force, regenerative power generation is performed by the motor generator 33 during inertial running or braking, and surplus kinetic energy is converted into electric power to charge the battery 35.

  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.

  By providing the speed reduction mechanism 30, the regenerative braking torque of the motor generator 33 can be increased by the speed reduction mechanism 30 regardless of the gear stage of the transmission 20 during inertia traveling during high speed travel, thereby improving the regenerative efficiency. can do.

  In addition, since the speed reduction mechanism 30 is only newly attached to the propeller shaft 25 of the vehicle, and the layout of the powertrain component can be changed very little, the conversion from the existing vehicle can be performed more easily than before. .

  Next, the HEV power soaring system will be described. In this power steering system, 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, and the first power steering pump 40 driven by the diesel engine 10. However, the power steering fluid 44 is pumped to the first hydraulic circuit 43. The steering unit 53 assists the steering of the steering 54 using the supplied power steering fluid 51. Note that since the HEV of this embodiment is a large vehicle, a hydraulic steering unit including a hydraulic power cylinder having a large output and excellent steering performance and reliability is used as the steering unit 53.

  The second power steering pump 45 is connected to the propeller shaft 25 via the speed reduction mechanism 30. A double check valve 49 for switching the power supply source of the power steering fluid 51 from the first power steering pump 40 to the second power steering pump 45, various hydraulic circuits (first hydraulic circuit 43, second hydraulic circuit 47 and main hydraulic circuit 50), and When the first power steering pump 40 is stopped by the switching device including the accumulator 52 as the diesel engine 10 is stopped, the power source fluid 51 supplied to the steering unit 53 is supplied from the first power steering pump 40 to the first power steering pump 40. It is switched to the 2 power steering pump 45.

  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. It should be noted that the upstream end portion of the first hydraulic circuit 43 upstream of the first power steering pump 40 and the upstream end portion of the second hydraulic circuit 47 upstream of the second power steering pump 45 store the power steering fluids 44 and 48. Not connected to reservoir tank. The main hydraulic circuit 50 communicates the double check valve 49 and the steering unit 53. Further, the middle of the passage of the main hydraulic circuit 50 is branched and connected to the accumulator 52.

The drive shaft 46 of the second power steering pump 45 is connected to the propeller shaft 25 via the speed reduction mechanism 30. Specifically, the propeller shaft 25 of the speed reduction mechanism 30 of the second power steering pump 45 and the motor generator 33 are connected. The first power transmission path 104 is connected to the propeller shaft 25 via a second power transmission path 105 arranged separately. In addition, the 1st power transmission path 104 and the 2nd power transmission path 105 can illustrate a gear mechanism, a belt mechanism, and a chain mechanism. If the second power transmission path 105 is configured to be connectable to the propeller shaft 25, the connection with the propeller shaft 25 can be released when the second power steering pump 45 is not driven, and the drive loss can be reduced accordingly.

  The double check valve 49 preferentially guides the higher one 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 a valve. Therefore, it is preferable that 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.

  The accumulator 52 accumulates the power steering fluid 51 (= 44, 48) supplied from the first power steering pump 40 and the second power steering pump 45 via the double check valve 49, and the supply source of the power steering fluid 51 is the double check valve 49. The accumulated power steering fluid 51 is supplied to the steering unit 53. Since this accumulator 52 can suppress a large fluctuation in the pressure of the power steering fluid 51 supplied to the steering unit 53, it is possible to avoid a deterioration in drivability.

  In this way, the second power steering pump 45 is connected to the propeller shaft 25 via the speed reduction mechanism 30, and the supply source of the power steering fluid 51 is switched from the first power steering pump 40 to the second power steering pump 45 by the switching device. Even when the power steering fluid 44 is not supplied from the first power steering pump 40 during traveling, the power steering fluid 48 pumped from the second power steering pump 45 driven by the rotational power of the propeller shaft 25 via the speed reduction mechanism 30 is converted into the steering unit. 53 can be supplied. Thereby, even if the diesel engine 10 is stopped during traveling, it is possible to avoid stopping the steering assist of the steering 54 during traveling.

  When the power steering fluid 44 is not supplied from the first power steering pump 40 during traveling, for example, when the diesel engine 10 stops, the first power steering pump 40 fails or the first hydraulic circuit 43 is damaged. A case where the vehicle falls into a situation and a case where the HEV travels only by the driving force of the motor generator 33 can be exemplified.

  Next, the air supply system will be described. In this air supply system, the drive shaft of the air compressor 61 is connected to the crankshaft 13 of the diesel engine 10 by a V-belt, a gear, or the like, and the air compressor 61 driven by the diesel engine 10 is connected to the first pneumatic line. Compressed air 65 is pumped to the air tank 64 via 63. The compressed air 65 accumulated in the air tank 64 is supplied to the pneumatic device via the second pneumatic pipe line 66. Examples of the pneumatic device include a clutch actuator 120, a foot brake 122, and an air suspension (not shown).

  The air compressor 61 is provided with an unloader valve 62. The unloader valve 62 is connected to the air tank 64 by a third pneumatic pipe 67 and is operated by the action of the pressure pt of the air tank 64. Specifically, when the pressure pt of the air tank 64 exceeds the upper limit pressure pa set based on the durability of the air tank 64, the compressed air is released from the air compressor 61 to the air tank 64 by releasing the compressed air. On the other hand, when the pressure pt of the air tank 64 becomes lower than the lower limit pressure pb set so as not to hinder the operation of the pneumatic device, the compressed air of the air tank 64 is supplied from the air compressor 61. Has started.

  The pressure sensor 87 is disposed in either the air tank 64 or the second pneumatic pipeline 66 and is supplied to each pneumatic device from the pressure of the compressed air 65 accumulated in the air tank 64 or from the second pneumatic pipeline 66. The pressure of the compressed air 65 is acquired.

  Next, the brake system will be described. This brake system includes a regenerative brake, an engine brake, and a foot brake 122, and an exhaust brake and a compression release brake may be provided as auxiliary brakes.

  The regenerative brake is a brake in which the control device 80 controls the inverter 34 to operate the motor generator 33 as a generator, and converts the rotational power of the propeller shaft 25 into electric power by power generation by regeneration of the motor generator 33.

  In the engine brake, when the clutch 15 is engaged by the clutch actuator 120 in a state where fuel injection to the cylinder 12 is stopped, mechanical friction loss due to mechanical friction and fluid resistance of intake and exhaust are obtained. It is a brake that transmits to the propeller shaft 25 as a braking force, a rotational drag such as a pump loss that occurs and a driving loss of auxiliary equipment consumed as energy for driving the first power steering pump 40 and the air compressor 61.

  The foot brake 122 is a brake that applies a braking force directly to the drive wheel 27 by pressing the brake shoe against the brake drum by an actuator (not shown) using the compressed air 65 accumulated in the air tank 64. In the foot brake 122, the flow rate of the compressed air 65 supplied from the air tank 64 is adjusted by the brake proportional control valve 123 based on the depression amount of the brake pedal detected by the brake pedal opening sensor 93.

  Next, the auto cruise mode will be described. This auto-cruise mode is used especially when driving on a highway, and the program stored in the control device 80 automatically runs HEV when the auto-cruise operation switch 81 is turned on by the driver. It is a mode that runs on the street.

  Specifically, when the auto-cruise operation switch 81 is turned on, the control device 80 performs map information and vehicle weight acquired by the map information acquisition device 82 for engine travel, assist travel, motor travel, and inertia travel. This mode is a mode in which HEV is automatically driven while being selected in a timely manner based on the vehicle weight M estimated by the estimation device 83 and maintaining the vehicle speed V acquired by the wheel speed sensor 84 within a preset target speed range.

  During the auto-cruise mode, if the accelerator pedal depression is detected by the accelerator opening sensor 92, the acceleration can be accelerated by the driving force from the diesel engine 10. When the brake pedal opening sensor 93 detects the depression of the brake pedal, the depression of a clutch pedal (not shown), or the release of the auto cruise operation switch 81 is released, the auto cruise mode is released. The

The target speed range is a range between the upper limit speed vb and the lower limit speed vc with reference to the target speed va. The target speed va, the upper limit speed vb, and the lower limit speed vc can be set to arbitrary values by the driver. For example, the target speed va is set to 70 km / h or more and 90 km / h or less, and the upper limit speed vb is the target speed vb. The speed va is set to 0 km / h or higher and +10 km / h or lower, and the lower limit speed vc is -10 km / h or higher to the target speed va, 0 km / h.
The following speed is set.

  The map information acquisition device 82 communicates with a satellite positioning system (GPS) connected to the control device 80 to acquire the current position of the HEV, and with a server storing 3D road data. It comprises means for acquiring three-dimensional road data including the slope θ and the travel distance s of the travel road, and means for extracting the slope θ and the travel distance s of the travel path from which the HEV will travel. As described above, a device that obtains a gradient θ for each traveling distance s by dividing a traveling distance s of 500 km or less into a traveling distance s every 500 m, and a device that obtains a traveling distance s for each gradient θ. It can be illustrated.

  The map information acquisition device 82 is not particularly limited as long as it has a function capable of acquiring at least the gradient θ and the travel distance s of the travel path. For example, the map information acquisition device 82 is stored in a drive recorder. An example of obtaining the gradient θ and the travel distance s of the travel path from the obtained three-dimensional road data is also possible. Further, the gradient θ may be calculated based on values acquired by the wheel speed sensor 84 and the acceleration sensor (G sensor) 85.

  The vehicle weight estimation device 83 is stored in the control device 80 and is transmitted to the drive wheel 27, specifically, a program for estimating the vehicle weight M when the control device 80 performs motor travel at the time of starting acceleration. Assuming that the driving force Fm is equal to the running resistance R, the motor rotation sensor 36 that obtains the output torque Tm of the motor generator 33 acquired by the inverter 34 and the rotation speed of the motor generator 33 in the motor running at the time of start acceleration. A program for estimating the vehicle weight M can be exemplified based on the acquired vehicle acceleration (hereinafter referred to as acceleration) a.

  The specific configuration of the vehicle weight estimation device 83 is not particularly limited as long as it has a function capable of estimating the vehicle weight M of HEV. However, the output torque Tm and acceleration at the time of starting acceleration by motor traveling are not limited. If the vehicle weight M is estimated based on a, the vehicle weight M can be estimated even when the vehicle speed V is low (speed of 30 km / h or less), and the rolling resistance Rr and air resistance of the running resistance R are estimated. Since each of Rd and the climbing resistance Rs can be disabled and the variables can be reduced, the vehicle weight M can be estimated more accurately and simply. In addition, the time of starting acceleration by motor running includes the time of HEV reverse.

  The control method in the auto cruise mode will be described below as a function of the control device 80. First, when the auto cruise operation switch 81 is turned on by the driver while the HEV is running, the control device 80 maintains the vehicle speed V within the target speed range based on the map information and the estimated vehicle weight M. Any one of engine running, assist running, motor running, and inertia running is selected as appropriate.

  The engine travels the HEV by the driving force Fe transmitted from the diesel engine 10 to the propeller shaft 25 via the clutch 15 and the transmission 20. In the assist travel, the HEV travels with both the driving force Fe from the diesel engine 10 and the driving force Fm transmitted from the motor generator 33 to the propeller shaft 25 via the speed reduction mechanism 30. In the motor travel, the HEV is traveled by the driving force Fm from the motor generator 33 with the clutch 15 disengaged. In inertial running, the HEV is run without transmitting the driving force of the diesel engine 10 and the motor generator 33 to the propeller shaft 25.

  Next, the control device 80 controls the clutch 15 to be disengaged and stop the fuel injection to stop the diesel engine 10 during coasting, and maintains the idling stop state during coasting. doing.

  As described above, even if the first power steering pump 40 is stopped when the diesel engine 10 is stopped, the power steering fluid 51 is constantly supplied from the second power steering pump 45 connected to the propeller shaft 25 to the steering unit 53. During the HEV traveling, the diesel engine 10 can be stopped without stopping the steering assist. Therefore, the fuel consumption during inertia traveling can be reduced by setting the clutch 15 to the disconnected state and stopping the diesel engine 10 by stopping the fuel injection during inertia traveling.

  Further, since the diesel engine 10 is stopped during coasting, the exhaust gas 71 from the exhaust valve 70 can be reduced, so that the exhaust gas is disposed in the exhaust passage 73 and passes through the exhaust manifold 72 from the exhaust valve 70. Thus, it is possible to suppress a reduction in the purification capacity of the exhaust gas purification device 75 that purifies the exhaust gas 71 that has driven the turbine 74. As a result, when the purification capacity of the exhaust gas purification device 75 is lowered, the fuel that does not contribute to the driving force of the HEV is injected to increase the temperature of the exhaust gas 71 to recover the purification capacity of the exhaust gas purification device 75. Since the opportunity for regeneration is reduced, the fuel consumption required for the regeneration can also be reduced. As the exhaust gas purification device 75, for example, a collection device that collects particulate matter in the exhaust gas 71 can be exemplified, and accumulation of particulate matter on the collection device is suppressed during motor running and inertia running. Therefore, fuel consumption necessary for regeneration of the collection device can be suppressed.

  In addition, the clutch 15 is disengaged during inertia traveling and the diesel engine 10 is stopped by stopping fuel injection, so that the rotational power of the propeller shaft 25 is reduced by the rotational drag of the diesel engine 10. Since this can also be avoided, energy loss during motor running and inertia running can be reduced to further improve fuel efficiency.

  In addition, the control device 80 may perform control to stop the diesel engine 10 by stopping the fuel injection while disengaging the clutch 15 while the motor is running.

  As described above, since the motor travel is stopped as well as the inertia travel, the fuel consumption during the motor travel can be reduced and the reduction in the purification capacity of the exhaust gas purification device 75 can be suppressed. Fuel consumption can be improved.

  In such HEV, while the control device 80 is decelerating during inertial running, when the pressure pt becomes equal to or less than the pressure determination value pc set to be lower than the lower limit pressure pb and lower than the upper limit pressure pa, the clutch 15 Is connected to operate the engine brake and the unloader valve actuator 127 to operate the unloader valve 62 to start the supply of the compressed air 65 from the air compressor 61 to the air tank 64. Composed.

  The unloader valve actuating device 127 is constituted by an on-off valve interposed in the third pneumatic pipe 67, and is opened and closed by an unloader control signal (current value) Ia from the control device 80, and the third loader valve operating device 127 is opened and closed. The pneumatic line 67 is opened and closed. In addition, as the unloader valve operating device 127, an actuator that directly opens and closes the valve body of the unloader valve 62 may be used.

  The pressure determination value pc is set to be higher than the lower limit pressure pb at which the unloader valve 62 operates and lower than the upper limit pressure pa. For example, the upper limit pressure pa is set to 0.7 MPa or more and 0.8 MPa or less, and the lower limit pressure pb Is set to 0.3 MPa or more and 0.5 MPa or less, the pressure judgment value pc is set to 0.5 MPa or more and 0.6 MPa or less.

A control method in the HEV auto-cruise mode will be described below as a function of the control device 80 based on the flowchart shown in FIG. In this control method, while traveling on the travel road, the control device 80 is coasting based on the gradient θ and travel distance s acquired by the map information acquisition device 82 and the vehicle weight M estimated by the vehicle weight estimation device 83. This is done when you select.

  First, in step S10, the control device 80 determines whether or not the pressure pt of the air tank 64 acquired by the pressure sensor 87 is equal to or lower than the pressure determination value pc. If the pressure pt exceeds the pressure determination value pc in step S10, the process returns to the start. If the pressure pt is equal to or less than the pressure determination value pc, the process proceeds to step S20.

  Next, in step S20, the control device 80 activates the engine brake and proceeds to step S30. In this step S20, the control device 80 transmits the clutch control signal Ic to the clutch proportional control valve 121, and supplies the compressed air 65 having a flow rate proportional to the clutch control signal Ic to the clutch actuator 120. The clutch 15 is brought into a connected state by the clutch actuator 120. As a result, the rotational power of the propeller shaft 25 is gradually transmitted to the crankshaft 13 through the transmission 20, and the crankshaft 13 rotates to operate the engine brake.

  At this time, the clutch control signal Ic sent by the control device 80 has a value smaller than the control signal at the time of shifting of the transmission 20 and is proportional to per unit time of the compressed air 65 supplied to the clutch actuator 120. It is preferable to reduce the flow rate of the clutch 15 and gradually move the clutch 15 from the disconnected state to the connected state. As described above, when the engine brake is operated during inertial running, if the clutch 15 is gradually changed from the disconnected state to the connected state, the impact when the rotational power is transmitted from the propeller shaft 25 to the crankshaft 13 can be suppressed. Therefore, it becomes advantageous for improvement of drivability.

  Next, in step S30, the controller 80 forcibly operates the unloader valve 62, and proceeds to step S40. In this step S30, the controller 80 sends an unloader control signal Ia to the unloader valve actuator 127, and the unloader valve actuator 127 is closed by the unloader control signal Ia, so that the third pneumatic line 67 is reached. Shut off. As a result, the supply of the compressed air 65 from the air tank 64 to the unloader valve 62 is stopped, and the pressure inside the unloader valve 62 is reduced to the lower limit pressure pb, so that the unloader valve 62 is generated in the air compressor 61. It operates so that the compressed air 65 can be supplied to the air tank 64.

  Next, in step S40, the control device 80 maintains the operation of the engine brake and proceeds to step S50. The air compressor 61 is driven by the crankshaft 13 that is rotated by operating the engine brake, and the compressed air 65 is supplied to the air tank 64.

  Next, in step S50, the control device 80 determines whether or not the pressure pt acquired by the pressure sensor 87 is equal to or higher than the upper limit pressure pa. If the pressure pt is less than the upper limit pressure pa in step S50, the process returns to step S40, and if the pressure pt is greater than or equal to the upper limit pressure pa, the process proceeds to step S60.

  Next, in step S60, the control device 80 disconnects the clutch 15 to stop the operation of the engine brake, and returns to the start.

  Since the control as described above is performed, when the pressure pt of the air tank 64 becomes equal to or lower than the pressure determination value pc while the inertia traveling is decelerating, the clutch 15 is engaged and the engine brake is operated. At the same time, the unloader valve 62 is operated to start the supply of compressed air from the air compressor 61 to the air tank 64, so that the pressure pt of the air tank 64 can be prevented from becoming lower than the lower limit pressure pb. Moreover, the opportunity to drive the air compressor 61 by driving the diesel engine 10 that has consumed fuel can be reduced by maintaining the pressure pt of the air tank 64 above the lower limit pressure pb.

  Thereby, in addition to the effect of reducing the fuel consumption by stopping the diesel engine 10 during inertial running, the pressure pt of the air tank 64 is maintained at a certain level or more, so that the diesel engine 10 is reduced in accordance with the decrease in the pressure pt of the air tank 64. Since the starting opportunity can be reduced, the fuel consumption can be further improved.

  In the HEV described above, it is desirable that the vehicle speed V is set while the inertial traveling is decelerating while the vehicle speed V exceeds the upper limit speed vb of the target speed range. When the vehicle speed V decelerates over the upper limit speed vb of the target speed range during inertial traveling, for example, deceleration on a steeply descending plate road where HEV is accelerated by gravity without transmitting the driving force to the propeller shaft 25 is exemplified. In this deceleration, the kinetic energy of the HEV is reduced by the brake.

  Therefore, by controlling the air compressor 61 to be driven using the lost kinetic energy while the vehicle speed V is decelerating beyond the upper limit speed vb of the target speed range, fuel efficiency can be more effectively achieved. Can be improved.

  In the HEV described above, when the control device 80 decelerates because the vehicle speed V exceeds the upper limit speed vb during inertial running, the regenerative brake is first activated, and the pressure pt of the air tank 64 is set to the pressure pt. It is desirable that the engine brake is configured to be controlled when the determination value pc or less is reached.

  By performing the control in this way, the regeneration opportunity of the motor generator 33 can be increased, and the power generation of the motor generator 33 by driving the diesel engine 10 that has consumed the fuel can be suppressed, so that the fuel efficiency can be further improved.

  In addition, in the HEV described above, when the control device 80 operates the unloader valve 62 by the unloader valve operating device 127, the rotational drag component of the diesel engine 10 that has driven the first power steering pump 40 and the air compressor 61 is used. It is desirable that the control is performed so as to reduce the regenerative braking force of the regenerative brake.

  The magnitude of the regenerative braking force of the regenerative brake can be changed by changing the frequency of the inverter 34 and the current value between the motor generator 33 and the battery 35, and the vehicle speed V has exceeded the upper limit speed vb. When the regenerative brake is first actuated when the vehicle is decelerating, the vehicle speed V is adjusted according to the required braking force that makes the upper limit speed vb (or the target speed va).

  When the unloader valve 62 is operated by the unloader valve actuating device 127, that is, when the engine brake is operated, this regenerative braking force is reduced by an amount increased by the operation of the engine brake. By operating both brakes of the engine brake, the kinetic energy of the HEV can be prevented from being reduced too much. Therefore, since loss of kinetic energy due to braking can be suppressed and inertial running can be maintained for a longer time, fuel consumption can be further improved.

  Furthermore, in the HEV described above, it is desirable that the control device 80 is configured to perform control to maintain the transmission 20 at a preset gear stage during inertial running. With this configuration, when the engine brake is operated, the rotational power from the propeller shaft 25 can be transmitted to the crankshaft 13 only by gradually bringing the clutch 15 into the connected state, so that the engine brake can be quickly applied. Can operate. The gear stage of the transmission 20 may be switched according to the rotation speed Np of the propeller shaft 25.

  4 and 5 show an example of the relationship among the vehicle speed V, the output torque Te of the diesel engine 10, the output torque Tm of the motor generator 33, the charge state Ce of the battery 35, and the altitude H in the auto-cruise mode. It is assumed that the negative output torque Te of the diesel engine 10 indicates engine braking, and the negative output torque Tm of the motor generator 33 indicates regenerative torque.

  As shown in FIG. 4, the steeply descending slope L1 is a descending slope where the slope θ1 is a steep downhill and the vehicle speed V is predicted to be maintained at the lower limit speed vc or more when it is assumed that the coasting is performed. is there. As such a steeply descending slope L1, for example, when the HEV vehicle weight M is 25 t, a descending slope where the gradient θ1 is 2% or more and the travel distance s1 is 500 m or more can be exemplified.

  On this steeply descending slope L1, the control device 80 acquires the gradient θ1 and travel distance s1 acquired by the map information acquisition device 82 and the vehicle weight M estimated by the vehicle weight estimation device 83 while traveling on the steep climbing slope L3. . Next, the control device 80 predicts the steeply descending slope L1 where the vehicle speed V is maintained at the lower limit speed vc or more when it is assumed that the vehicle travels inertially based on the gradient θ1, the travel distance s1, and the vehicle weight M. Next, coasting starts from before the steeply descending slope L1.

  Since HEV gravity-accelerates on such a steeply descending slope L1, vehicle speed V exceeds upper limit speed vb at an early stage when driving force is applied by engine traveling, assist traveling, and motor traveling, thereby causing engine braking and footing. More energy is lost by braking. Therefore, in such a steeply descending slope L1, energy loss can be reduced by performing coasting as in the above-described control, so that fuel efficiency can be further improved.

  As shown in FIG. 5, the gentle downhill road L2 is a downhill, but the gradient θ2 is gentle, and the running resistance cannot be overcome only by the force in the forward direction due to the gravitational acceleration applied to the vehicle body. This is a downhill road in which the vehicle speed V cannot be maintained within the target speed range unless such driving force is applied to the propeller shaft 25.

  Specifically, when it is assumed that the vehicle has traveled inertially, the vehicle speed V is predicted to be less than the lower limit speed vc, and it is assumed that the engine travel or assist travel has been performed so as to maintain the vehicle speed V at the target speed va. This is a downhill road where the fuel consumption rate (SFC) Se of the diesel engine 10 is predicted to deteriorate. As such a gentle downhill road L2, for example, when the HEV vehicle weight M is 25 t, a downhill road where the gradient θ2 is less than 2% and the travel distance s2 is 500 m or more can be exemplified.

  On the gentle downhill road L2, the control device 80 acquires the gradient θ2, the travel distance s2, and the vehicle weight M while traveling on the flat road L0. Next, the control device 80 predicts the gentle downhill road L2 that travels by repeating the acceleration travel and the inertia travel based on the gradient θ2, the travel distance s2, and the vehicle weight M.

Next, the control device 80 performs inertial running until the vehicle speed V reaches the lower limit speed vc and engine running until the vehicle speed V reaches the upper limit speed vb, and charges the battery 35 by regenerative power generation of the motor generator 33. When the vehicle speed V is set to the upper limit speed vb, the control device 80 refers to the map data in which the fuel consumption rate Se based on the engine speed Ne and the output torque Te of the diesel engine 10 is set. The diesel engine 10 may be driven so that the fuel consumption rate Se becomes the lowest fuel consumption rate. Further, the control device 80 regenerates the motor generator 33 with a torque that is excessive to accelerate the vehicle speed V to the upper limit speed vb. If there is a sufficient charge in the battery 35 and the torque for accelerating the HEV is insufficient, the motor generator 33 may be rotated to compensate for the insufficient torque, and the HEV is increased to the acceleration torque. If there is no shortage, the motor generator 33 may be stopped.

  In such a gentle downhill road L2, if the diesel engine 10 is driven by engine running and assist running to maintain the vehicle speed V at the target speed va, the fuel consumption rate of the diesel engine 10 becomes high and the fuel consumption deteriorates. Thus, on such a gentle downhill road L2, the fuel efficiency can be improved by performing a wave-like operation that repeats the acceleration traveling at a low fuel consumption rate of the diesel engine 10 and the deceleration traveling at which no fuel is consumed.

  As shown in FIGS. 4 and 5, when the vehicle decelerates to inertia travel, if the pressure pt detected by the pressure sensor 87 is equal to or lower than the pressure determination value pc at the point A, the control device 80 puts the clutch 15 in the engaged state. Activate the engine brake. Further, when the regenerative brake is operating, the regenerative braking force of the regenerative brake is decreased. At the same time, the control device 80 operates the unloader valve 62 by the unloader valve operating device 127. Thereby, supply of the compressed air 65 from the air compressor 61 to the air tank 64 is started, and the pressure pt increases.

  Next, at point B, when the pressure pt detected by the pressure sensor 87 becomes equal to or higher than the upper limit pressure pa, the unloader valve 62 operates so as to release the compressed air 65 generated by the air compressor 61. At this time, the control device 80 disengages the clutch 15 and stops the operation of the engine brake.

  As described above, when the vehicle is decelerated during inertial running, if the pressure pt falls below the pressure determination value pc, the air compressor 61 is driven by operating the engine brake, so that the compressed air supplied to the pneumatic device The pressure pt of 65 can be maintained above a certain level.

DESCRIPTION OF SYMBOLS 10 Diesel engine 15 Clutch 20 Transmission 25 Propeller shaft 26 Differential 27 Drive wheel 30 Deceleration mechanism 32 Rotating shaft 33 Motor generator 40 First power steering pump 45 Second power steering pump 49 Double check valve 53 Steering unit 61 Air compressor 62 Unloader valve 64 Air tank 65 Compressed air 80 Control device 81 Auto cruise operation switch 82 Map information acquisition device 83 Vehicle weight estimation device 84 Wheel speed sensor 87 Pressure sensor 120 Clutch actuator 121 Clutch proportional control valve 127 Unloader valve operation device

Claims (5)

A propeller shaft for coupling a transmission connected to a diesel engine via a clutch and a differential for driving a drive wheel; a hybrid system having the diesel engine and a motor generator; and a first power steering pump coupled to the diesel engine; A steering unit that assists steering by using the power steering fluid supplied from the first power steering pump, an air compressor coupled to the diesel engine, and an air tank that accumulates compressed air supplied from the air compressor; A pneumatic device driven using compressed air supplied from the air tank, and compressed air from the air compressor to the air tank when the pressure of the air tank exceeds a preset upper limit pressure An unloader valve for stopping supply and starting the supply of compressed air from the air compressor to the air tank when the pressure falls below a preset lower limit pressure, a regenerative brake for regeneratively driving the motor generator, and the diesel engine An engine brake that applies rotational resistance of the engine to the propeller shaft, a map information acquisition device that acquires map information, a vehicle weight acquisition device that acquires vehicle weight, a vehicle speed acquisition device that acquires vehicle speed, and the pressure In a hybrid vehicle including a pressure acquisition device and a control device,
A reduction mechanism that connects the propeller shaft and the rotation axis of the motor generator with the rotation axis of the motor generator as an input shaft and the propeller shaft as an output shaft, and is coupled to the propeller shaft via the reduction mechanism. When the first power steering pump stops with the stop of the diesel engine, the power steering fluid supplied to the steering unit is supplied from the first power steering pump to the second power steering pump. A switching device for switching to a pump, and an unloader valve actuating device for forcibly operating the unloader valve to start the supply of compressed air from the air compressor to the air tank,
When the auto cruise mode for maintaining the vehicle speed within a preset target speed range is set for the control device, inertial traveling that does not transmit the driving force of the diesel engine and the motor generator to the propeller shaft is performed on the map. When selecting based on the information and the vehicle weight, in addition to performing the control to stop the diesel engine by stopping the fuel injection and stopping the clutch during the inertia traveling,
When the pressure is below the pressure judgment value set above the lower limit pressure and less than the upper limit pressure while decelerating during inertial running with the diesel engine stopped, the clutch is brought into a connected state. The engine brake is operated, and the unloader valve is operated by the unloader valve actuating device to perform control for starting the supply of compressed air from the air compressor to the air tank. Hybrid vehicle.   2. The hybrid vehicle according to claim 1, wherein the vehicle speed is set while the vehicle is decelerating while the inertia is running while the vehicle speed exceeds the upper limit speed of the target speed range.   When the vehicle speed decelerates beyond the upper limit speed, the control device first activates the regenerative brake, and activates the engine brake when the pressure falls below the pressure determination value. The hybrid vehicle according to claim 2, wherein the hybrid vehicle is configured to perform.   When the unloader valve is actuated by the unloader valve actuating device, the control device lowers the braking force of the regenerative brake by the rotational drag of the diesel engine driving the first power steering pump and the air compressor. The hybrid vehicle according to claim 3, wherein the hybrid vehicle is configured to perform control. When the auto cruise mode is set, the driving force transmitted from the diesel engine to the propeller shaft via the clutch and transmission, and the driving force transmitted from the motor generator to the propeller shaft via the speed reduction mechanism Any one of the engine traveling, the assist traveling, and the motor traveling that travels on either side, and the inertia traveling that does not transmit the driving force of the diesel engine and the motor generator to the propeller shaft by stopping the diesel engine. Select timely based on information and vehicle weight, and automatically drive while maintaining the vehicle speed within a preset target speed range,
When the inertial running is selected, the clutch is disengaged to stop the diesel engine, and instead of the first power steering pump that is stopped when the diesel engine is stopped, the speed reduction mechanism is changed from the propeller shaft. A method for controlling a hybrid vehicle that drives a second power steering pump with rotational power transmitted via a power supply to supply power steering fluid to a steering unit,
While the vehicle is decelerating during inertial running, the pressure of the air tank to which compressed air is supplied from the air compressor driven by the diesel engine causes the unloader valve to supply compressed air from the air compressor to the air tank. When the lower limit pressure to start, and when the unloader valve falls below the pressure determination value set below the upper limit pressure to stop the supply of compressed air from the air compressor to the air tank,
The clutch is engaged and an engine brake that applies a rotational drag force of the diesel engine to the propeller shaft is operated, and the unloader valve is forcibly operated so that the compressed air from the air compressor to the air tank is A control method of a hybrid vehicle, characterized by starting supply.