JPH0874608A - Vehicle engine having braking energy recovering device - Google Patents

Abstract

PURPOSE: To effectively improve running fuel consumption performance by providing a control device which opens and closes first and second changeover valves of a main hydraulic circuit and a branched hydraulic circuit according to an operation condition of a car and an engine, and reducing a rate of smoke in exhaust gas at the time of starting and accelerating. CONSTITUTION: An engine 10 for a car has an intake valve closing timing varying device. A volume type supercharger 18 is driven by a hydraulic motor 20. A variable volume type hydraulic pump 30 is driven by braking energy of the engine 10 an the car. A main hydraulic circuit 42 connects the hydraulic motor 20 to the variable volume type hydraulic pump 30. A branched hydraulic circuit 46 is connected to the main hydraulic circuit 42. An accumulator 48 is arranged on the branched hydraulic circuit 46. A first changeover valve 44 is provided on the main hydraulic circuit 42 between the branched part of the branched hydraulic circuit 46 and the hydraulic motor 20, while a second changeover valve 50 is arranged between the branched hydraulic circuit 46 between the branched part and the accumulator 48. A controller 64 opens and closes the first and second changeover valves 44, 50 according to an operation condition of the car and the engine 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle engine equipped with a braking energy recovery device, which is suitable for use in a vehicle, particularly a route bus in which starting and stopping are frequently repeated.

[0002]

2. Description of the Related Art Conventionally, an engine such as a route bus is provided with a displacement type supercharger using a hydraulic motor as a drive source and a variable displacement hydraulic pump driven in conjunction with the crankshaft of the engine. An engine for a vehicle with a supercharger is used in which pressure oil discharged from the hydraulic pump is supplied to the hydraulic motor for driving the supercharger.

Now, the schematic structure of the conventional engine for a vehicle with a supercharger will be described with reference to the conceptual configuration diagram of FIG. 12. Reference numeral 10 in the figure generally indicates a four-cycle diesel engine for a route bus, The engine 10 has an intake pipe 12
And an exhaust pipe 14. In the main intake passage 16 of the intake pipe 12, a capacity type supercharger 18 of an appropriate type such as a roots type or a Risholum type is interposed. The supercharger 18 is a swash plate type axial piston type hydraulic motor, a gear motor, or other appropriate hydraulic pressure. It is driven by the motor 20.

On the other hand, the crankshaft 22 of the engine 10 is provided with a crank gear 24 for extracting power, and the crank gear 24 is provided with a pump drive gear 28 via an idler gear 26.
Drive. The pump drive gear 28 is fixed to a pump shaft 30 'of a variable displacement hydraulic pump 30, and the hydraulic pump 30 has a cylinder block that rotates integrally with the pump shaft 30' and a pump shaft formed on the cylinder block. A plurality of cylinders each of which includes an axis in a cylindrical surface or a conical surface concentric with the axis of the pump, a pump piston or a plunger slidably fitted in the cylinder, and an inclination angle with respect to the pump axis. A movable swash plate or tilting plate capable of moving and a tilting angle of the tilting plate with respect to a plane perpendicular to the pump shaft axis, that is, a tilting angle are controlled to change the effective stroke of the piston or the plunger to discharge the amount of discharged hydraulic oil. A well-known swash plate type variable displacement hydraulic pump including an actuator for controlling the above, and other appropriate variable displacement hydraulic pump are used.

In the figure, reference numeral 32 is an oil tank or reservoir, 34 is a flywheel fixed to the output side end of the crankshaft 22, and 36 is a little upstream side from the atmospheric opening end of the exhaust pipe 14. It is a muffler installed in. Also,
The flywheel 34 cooperates with a clutch device (not shown), and the clutch device is connected to drive wheels of the vehicle through a transmission device, a propeller shaft, a differential gear device and an axle to transmit power to the vehicle. Make up the system. Further, the intake pipe 12 is provided with a bypass intake passage 38 for bypassing the positive displacement supercharger 18 and taking the outside air into the engine as natural intake, if necessary. An on-off valve 40 that opens and closes is provided.

When the conventional displacement type supercharged vehicle engine is adopted for a route bus, the hydraulic motor 20 is increased by increasing the amount of oil discharged from the variable displacement hydraulic pump 30 at the time of high load such as starting and accelerating. By increasing the pressure oil supply amount to the exhaust gas, the intake air discharge amount of the positive displacement supercharger 18 can be increased commensurate with the increase in the fuel amount, so that the increase in the smoke amount in the exhaust gas can be effectively suppressed. You can However, it has not been possible to improve the poor running fuel efficiency due to the running mode peculiar to a route bus that starts and stops frequently.

[0007]

SUMMARY OF THE INVENTION The present invention was devised in view of the above circumstances, and it is possible to effectively reduce the amount of smoke in exhaust gas at the time of starting and accelerating, and to effectively reduce running fuel consumption. The main purpose is to provide a vehicle engine that can be improved and is particularly suitable for a route bus in a traveling mode in which start and stop are frequently repeated (though not limited to the route bus, of course). It is another object of the present invention to provide a vehicle engine of this type that can absorb a large amount of energy and thus reduce the burden on the service brake.

[0008]

To achieve the above object, the present invention is driven by a vehicle engine equipped with an intake valve closing timing changing device capable of changing the opening timing of an intake valve, and a hydraulic motor. A positive displacement supercharger that supplies pressurized intake air to the engine, a variable displacement hydraulic pump that is interposed in the power transmission system of the vehicle and that is driven by the braking energy of the engine and the vehicle, and the hydraulic motor A main hydraulic circuit connecting the hydraulic oil inlet and the hydraulic oil discharge port of the variable displacement hydraulic pump, a branch hydraulic circuit connected to the main hydraulic circuit, and a pressure accumulator interposed in the branch hydraulic circuit, A first switching valve provided in a main hydraulic circuit between the branch portion of the branch hydraulic circuit and the hydraulic motor; and a second switching valve provided in a branch hydraulic circuit between the branch portion and the pressure accumulator. , The first switching valve and The second switching valve is to propose a braking energy recovery device with a vehicle engine, characterized in that a control device for opening and closing according to the operating condition of the vehicle and the engine.

The variable displacement hydraulic pump is a swash plate type variable displacement hydraulic pump having a tilting plate capable of controlling the amount of discharged hydraulic oil by controlling a tilting angle formed with respect to a plane perpendicular to the pump shaft. It is preferably a pump.

Further, it is preferable that the branch hydraulic circuit between the second switching valve and the pressure accumulator is provided with a variable orifice or a throttle valve whose passage area is controlled according to the operating states of the vehicle and the engine. .

Further, the control device is arranged so that the amount of hydraulic fluid discharged from the variable displacement hydraulic pump, the amount of hydraulic fluid discharged from the variable displacement hydraulic pump, and the first amount of the hydraulic fluid can be changed according to the accelerator opening representing the amount of fuel supplied to the engine, the pedal effort of the brake pedal for operating the normal brake, and the vehicle speed. It is preferable to control the opening / closing of the first switching valve and the second switching valve and the intake valve closing timing changing device, respectively.

Further, when the accelerator opening is equal to or larger than the set opening, the vehicle speed is lower than the first set vehicle speed, and the hydraulic oil pressure in the pressure accumulator is equal to or larger than the first set value, , The first switching valve and the second switching valve are both opened to supply the high pressure hydraulic oil of the pressure accumulator to the hydraulic motor to drive the positive displacement supercharger, and the intake valve closing timing changing device is operated to intake air. The valve is preferably configured to be closed early.

Further, when the accelerator opening is equal to or larger than the second preset opening which is larger than the first preset opening, the control device causes the variable displacement hydraulic pump to discharge the amount of hydraulic oil which increases in accordance with the accelerator opening. The first switching valve is opened, the second switching valve is closed, the hydraulic motor is driven by the hydraulic fluid discharged from the hydraulic pump, and the positive displacement supercharger pressurizes the hydraulic motor. It is preferable that the intake air is supplied to the engine.

Furthermore, when the vehicle speed is equal to or higher than the second set low vehicle speed and the brake pedal of the service brake is depressed, the control device causes the variable displacement hydraulic pump to increase the hydraulic oil that increases in accordance with the brake pedal force. The first switching valve is closed and the second switching valve is opened while being controlled to discharge, and the hydraulic fluid discharged from the hydraulic pump is supplied to the pressure accumulator through the branch hydraulic circuit. Preferably.

The discharge intake pressure of the positive displacement supercharger is from 4 to
12 kg / cm ^{2 It is} preferably set to about 10 kg / cm ² . Further, when the high-pressure hydraulic oil in the pressure accumulator is supplied to the hydraulic motor via the variable orifice or throttle valve, the second switching valve and the first switching valve, the positive displacement supercharger driven by the hydraulic motor. It is preferable that the passage area of the variable orifice or the throttle valve is controlled so that the discharge intake pressure of the machine becomes a set pressure.

[0016]

According to the present invention, when the brake pedal is depressed while the vehicle is traveling, the variable displacement hydraulic pump effectively absorbs the braking energy of the vehicle and discharges high pressure oil. The discharged pressure oil is stored in a pressure accumulator connected to the branch hydraulic circuit. At the time of starting and accelerating the vehicle, the high-pressure pressure oil stored in the pressure accumulator is supplied to the hydraulic motor to rotate the positive displacement supercharger at a high speed, so that intake air of 4 to 12 kg /
It is pressurized to a high pressure of cm ² , preferably 10 kg / cm ² . On the other hand, when the accelerator pedal is depressed more than the set depression amount for starting and accelerating, the intake valve closing timing changing device of the engine is actuated to close the intake valve early, and as a Miller cycle engine with excellent cycle thermal efficiency. Although the engine is operated and the high-pressure supercharged intake air is supplied despite the early closing of the intake valve, the engine operates with high output and high efficiency. As described above, the braking energy of the vehicle is converted into the pressure energy of the pressure oil by the variable displacement hydraulic pump and stored in the pressure accumulator, and the energy of the pressure oil stored in the pressure accumulator is used to drive the positive displacement supercharger. Driven to obtain high-pressure intake air and the synergistic effect of high-efficiency Miller cycle operation by closing the intake valve on the engine side early, improving smoke performance during start and acceleration and improving running fuel consumption And are achieved at the same time.

[0017]

Embodiments of the present invention will be described below with reference to FIGS. 1 to 11. (Note that members and parts that are substantially the same as or correspond to those of the conventional configuration described above with reference to FIG. 12 are denoted by the same reference numerals, and duplicate description will be omitted.) First, the schematic diagram of FIG. As described above, according to the present invention, the main hydraulic circuit 42 that connects the oil inlet of the hydraulic motor 20 that drives the positive displacement supercharger 18 and the oil outlet of the variable displacement hydraulic pump 30 has a first structure. The switching valve 44 is provided, and the oil discharge port of the hydraulic pump 30 and the first
A branch hydraulic circuit 46 is provided in the main hydraulic circuit 42 between the switching valve 44 and
Is connected.

An appropriate pressure accumulator 48, preferably a piston spring type pressure accumulator, is connected to the branch hydraulic circuit 46, and the branch hydraulic circuit 4 on the upstream side of the pressure accumulator 48 is connected.
A second switching valve 50, a variable orifice or throttle valve 52, a relief valve 54, and an oil cooler 56 are connected to the inside of the engine 6 sequentially from the upstream side, and the oil cooler 56 is of course communicated with the oil tank or the oil sump 32. The operating oil is cooled by using the cooling water of the engine 10 or the running wind as a cooling medium. Reference numeral 58 is a main hydraulic circuit 42 between the hydraulic oil discharge port of the variable displacement hydraulic pump 30 and the branch portion of the branch hydraulic circuit 46.
A check valve 60 for preventing backflow is interposed between the variable orifice or throttle valve 52 and a check valve provided in a bypass oil passage 62 connected to the branch hydraulic circuit 46 at both ends thereof. The first and second switching valves 44 and 50, the variable displacement hydraulic pump 30, the variable orifice or throttle valve 52, and an intake valve closing timing changing device for the engine 10 whose details will be described later are shown in FIG. Each of them is controlled by a controller or control device 64 conceptually shown in FIG.

The positive displacement supercharger 18 has a pressure higher than that of a normal pressure, for example, 4 to 12 kg / cm ² , preferably 10 kg.
In order to obtain supercharged intake air of / cm ^2, a high-pressure air compressor such as a Lisholm type air compressor is adopted, and the pressure accumulator 48 is a spacer mounted on the vehicle and energy to be stored as high-pressure hydraulic oil, that is, hydraulic pressure during start and acceleration. and a sufficient durability and safety against high pressure of 250kg ^/ cm ² ~300kg ^/ cm 2 from the viewpoint of the pressure energy of the hydraulic oil to be supplied to the motor 20, moreover may be acceptable mounting space of the vehicle Inexpensive piston that has a large capacity in the range and has few failures and excellent durability
Spring-type pressure accumulators are preferred. Furthermore, since the high-pressure hydraulic oil is used as the working medium in the hydraulic motor 20, it is preferable to employ an axial piston hydraulic motor having an inclined plate with a fixed tilt angle.

As the variable displacement hydraulic pump 30, an axial piston type hydraulic pump having a swash plate or a tilt plate with a variable tilt angle as shown in FIGS. 2 and 3 can be used. preferable. Hydraulic pump 3 as shown
0 comprises a cylinder block 66 splined to the pump shaft 30 ′, in which the cylinder block 66 has a cylindrical or conical surface concentric with the axis of the pump shaft (in the case shown the latter is illustrated). A plurality of cylinders 68, each of which includes each axis, are formed. A piston or a plunger 70 is slidably fitted in each of the cylinders 68, and a spherical end portion 7 of each piston 70 projecting out of the cylinder.
A shoe 74 is engaged with 2.

The cylinder block 66 is rotatably housed in a casing 76 having a substantially cylindrical inner peripheral surface. The casing 76 has end plates 78 at both ends in the axial direction of the pump. And 80 are attached. An annular swash plate or tilt plate 82 is concentrically arranged inside the casing 76 outside the pump shaft 30 ′, and the shoe 74 of each piston 70 is in sliding contact with one side surface of the tilt plate 82. ing.

On the tilt plate 82, one side surface of the tilt plate 82, which is in sliding contact with the shoe 74, forms an angle with respect to a plane orthogonal to the axis of the pump shaft 30 ', a so-called tilt angle (θ _p ). Is engaged with a pin 84, and the pin 84 is provided outside the tilt angle control piston 86. The tilt angle control piston 86 is slidably fitted in a cylinder 88 attached to the casing 76, and the pressure chambers 9 on both sides thereof are fitted.
Neutral springs 92a and 92b for constantly biasing the piston 86 toward the neutral position are provided at 0a and 90b. In addition, the oil tank 3 is attached to the end plate 78.
A suction hole 94a for sucking the working oil in 2 and a discharge hole 94b for discharging the pressurized working oil are provided.

The tilt angle control piston 86 is controlled by a displacement control solenoid valve device generally indicated by reference numeral 96 in FIG. The solenoid valve device 96 is a 4-port servo valve, and includes a spool 98 and solenoids 100a and 100b provided at both ends of the spool 98. These solenoids 100a and 100b are connected via a power supply connector 100c, respectively. Connected to the controller or control device 64. The spool 98 is displaced according to the control current value of the drive signal from the controller or controller 64 supplied to the solenoids 100a and 100b, and when no drive signal is supplied to either of the solenoids 100a and 100b, the spool 98 is the same spool. 98 is held in the neutral position shown.

When a drive signal is applied from the controller or control device 64 to either of the solenoids 100a and 100b, the spool 98 is displaced according to the drive signal value, and an oil pump normally attached to the engine 10 (described later). The hydraulic oil from the reference numeral 154 in FIG. 4) is used as one of the pressure chambers 90a or 9a of the tilt angle control piston 86.
0b and the other pressure chamber 90b or 90
The oil a is communicated with the oil tank 174 or the oil tank 32 described later, and the oil is drained. As a result, the tilt angle θ _p of the tilt plate 82 is controlled. At this time, the displacement of the tilt angle control piston 86 is transmitted to the spool 98 via the feedback mechanism 102, the spool 98 returns to the neutral position, and the tilt angle θ _p of the tilt plate 82 is required. Controlled by angle. When the pump shaft 30 ′ rotates, the piston 70 reciprocates with a stroke corresponding to the tilt angle θ _p , pressurizes the working oil sucked from the suction hole 94a to a high pressure, and discharges it from the discharge hole 94b to the main hydraulic circuit 42. Supply to. Of course, when the tilt angle θ _p is 0, the piston 70 does not reciprocate, and the discharge amount of the hydraulic pump 30 becomes zero. Since the structure of the variable displacement hydraulic pump 30 is known per se, a more detailed description will be omitted.

Next, the engine 10 has an intake valve closing timing changing device or an intake valve early closing device for realizing a Miller cycle, which is known to have higher theoretical thermal efficiency than an ordinary diesel engine or gasoline engine. Is provided. Now, an example of a specific structure of the intake valve closing timing changing device will be described with reference to FIGS.

First, in the block diagram showing the entire apparatus of FIG. 4, reference numeral 104 is a crankcase of the engine 10, 106 is supported in the crankcase 104, and is halved in conjunction with the crankshaft 22. , 108 is an intake cam integrally formed on the cam shaft 106, 110 is a guide hole formed in the crankcase 104 so as to face the intake cam 108, 112
Is a bottomed cylindrical or downward cup-shaped tappet body that is slidably fitted in the guide hole 110 and has a lower end opened.
114 is a plunger slidably and coaxially fitted in the tappet body 112, and 116 is the plunger 1
A push pin slidably fitted in a hollow hole 118 formed coaxially in the shaft 14, and 120 is the plunger 11
The push pin 116 housed in the hollow hole 118
Is pressed toward the upper closed end surface of the tappet body 112, and the lower end surface of the plunger 114 is pressed against the intake cam 108.
It is a return spring that presses against.

On the upper end surface of the tappet body 112,
Recess 12 that receives the lower spherical surface of push rod 122
4 is formed, and the upper end of the push rod 122 is operatively connected to an adjusting screw 128 screwed to one end of a rocker arm 126 pivotally supported on a cylinder head (not shown) via a rocker shaft. The other end of the rocker arm 126 is in contact with the stem 130 of the intake valve V _i , only a part of which is shown by a chain double-dashed line in the figure. An end ring 132 is fitted on the outer circumference of the lower end of the tappet body 112, and the end ring 132 is fixed to the crankcase 104 by a snap ring 134.

Inside the plunger 114, there is a hollow hole 118 and a push pin 116 fitted in the hollow hole.
The first oil chamber 136 is formed by
6 communicates with a first annular groove 140 formed on the outer circumference of the plunger 114 via an oil hole 138. First annular groove 1
40 communicates with the second annular groove 144 recessed in the outer periphery of the tappet body 112 through the oil hole 142, and the inner peripheral surface of the guide hole 110 facing the second annular groove 144 has an inner peripheral surface of the tappet body 112. The second annular groove 14 is always provided regardless of the vertical displacement.
A third annular groove 146 communicating with No. 4 is recessed. In addition, the land 148 of the tappet body 112 and the end ring 132 form an annular second oil chamber 150 that surrounds the outer periphery of the tappet body 112, and further annularly on the inner peripheral surface of the guide hole 110 adjacent to the land 148. The third oil chamber 152 is formed.

Discharge pressure oil from the oil pump 154 enters the third annular groove 146 which communicates with the first oil chamber 136 through the oil hole 138, the first annular groove 140, the oil hole 142 and the second annular groove 144. First oil passage 15 with check valve 156
8, the third annular groove 146 or the check valve 1
To the first oil passage 158 downstream of 56, a first discharge passage 162 whose opening / closing is controlled by a normally closed electromagnetic valve 160 is connected. Further, the discharge pressure oil of the oil pump 154 is supplied to the second oil chamber 150 from a second oil passage 166 having a check valve 164, and the second oil chamber 150 or the second oil chamber downstream of the check valve 164. The second oil passage 166 is connected to a second discharge passage 170 having an orifice for controlling the flow rate or a throttle valve 168. Further, a third discharge passage 172 is connected to the third oil chamber 152, and the first and second oil passages 158 and 166 and the first to third discharge passages 162, 170 and 172 are respectively an oil tank or an oil tank. It is led to the reservoir 174. This oil tank 17
4 may be an oil tank for the variable displacement oil pump 30 and the oil motor 20 or a tank common to the oil reservoir 32. Furthermore, the solenoid valve 160 is opened and closed by the controller or the control device 64.

An operation mode of the intake valve closing timing changing device will be described. During the operation of the engine 10, the controller or the control device 64 is instructed by the vehicle speed V _h and the engine speed N.
_e , the crank angle θ _{c of} each cylinder, and other information described later in detail are supplied as input signals from the sensors. Then, the intake valves V _i early closing condition described later is satisfied, the drive output is not supplied to the electromagnetic valve 160 from the controller 64, the solenoid valve is closed.

In this state, the pressure oil discharged from the oil pump 154 is supplied to the first oil passage 158 and the third annular groove 1.
46, second annular groove 144, oil hole 142, first annular groove 14
0 and the oil hole 138, the push pin 116 is supplied to the first oil chamber 136 and pushed in a direction in which the push pin 116 extends upward with respect to the plunger 114. 114, the maximum total length is maintained as shown in FIG. 5, and the rocker arm 126 causes the stem 130 of the intake valve V _i via the push rod 122 that is in contact with the tappet body 112. And the lower end surface of the plunger 114 is in contact with the intake cam 108 without a gap.

On the other hand, the pressure oil is supplied to the second oil chamber 150 from the second oil passage 166, and when the intake valve is opened, the pressure oil is supplied to the second oil chamber 150 as shown in FIG. 3 oil chamber 1
52 to the third discharge passage 172 through, also when the intake valve V _i is closed, as shown in Figure 6, the second discharge passage 170 is limited to flow through as orifice or throttle valve 168 Oil Return to tank 174. Therefore, the intake valve V _{i in accordance with} the rotation of the intake cam 108 is shown in the valve lift diagram of FIG. 7 (the diagram showing the valve lift L _v on the vertical axis and the crank angle θ _c on the horizontal axis). Solid curve l _i
Open and close in normal valve lift mode as indicated by. The curve l _e shown by the dotted line in FIG. 7 is the lift of the exhaust valve (not shown).

Next, the intake valve V whose vehicle operating condition will be described later is described.
_{When the} condition for early closing of _i is satisfied, the drive output is supplied from the controller or the control device 64 to the solenoid valve 160 in the vicinity of the crank angle θ ₁ at which the intake cam 108 substantially reaches the maximum lift. The solenoid valve 160 is opened. Therefore, until the crank angle θ ₁ is reached, the intake valve V _i opens in accordance with the solid lift curve l _i as shown in FIG. 7, and the solenoid valve 160 is opened near the crank angle θ _1.
6 is opened and the first discharge passage 162 is opened to the atmosphere, the pressure oil in the first oil chamber 136 is discharged into the oil tank 174 through the first discharge passage 162, so that it is shown in FIG. So that the push pin 116 has the return spring 1
The tappet body 1 is displaced downward while compressing 20.
The axial dimension of 12 and the plunger 114 is rapidly reduced, and as shown by the alternate long and short dash line l _ir in the intake valve lift diagram of FIG. At this time, when the communication between the second oil chamber 150 and the third oil chamber 152 is blocked by the land 148, the pressure oil in the second oil chamber 150 flows from the second discharge passage 170 through the orifice 168 after that time. As the displacement drop amount δ increases, the pressure of the working pressure oil in the second oil chamber 150 increases, and the intake valve V _{i that} closes early as described above is closed. The valve speed can be reduced and the intake valve V _i
The impact on the valve seat when seated, that is, when the valve is closed can be alleviated, and the operating noise of the engine can be reduced.

By early closing the intake valve V _i as described above, in the case of the 4-cycle diesel engine 10 with a supercharger, the P-V diagram as shown in FIG. 8 is obtained. In FIG. 8, point A represents the time when the intake valve V _i is closed early. By closing the intake valve V _i early and by supplying high-pressure intake air, preferably 10 kg / cm ² pressurized intake air by the positive displacement supercharger 18, from the intake valve V _i into the cylinder of the engine, Area B shown by hatching in the figure
The positive work can be obtained by the amount corresponding to, and high thermal efficiency can be obtained. (The region D indicated by a dotted line in the figure shows the negative work of the intake stroke in the P-V diagram of a conventional four-stroke diesel engine intake valve V _i does not early closing.) Thus, the engine 10 Among the various operating states, the intake valve V _i is closed early at the time of starting and accelerating, and the high pressure supercharging described above is performed to improve the smoke performance of the exhaust gas. By improving the acceleration performance and, at the same time, driving the positive displacement supercharger 18 by using the pressure oil that has absorbed the braking energy of the vehicle as the energy of the pressure, as will be described in detail later, the improvement of the fuel consumption is achieved. It is clear that

On the other hand, as shown in FIG. 9, an accelerator pedal 176 is provided on the floor near the driver's seat of a vehicle such as a route bus in order to control the amount of fuel supplied to the engine 10. Same accelerator pedal 176
A pedal shaft 178 is fixed to the lower end portion of the pedal, and the pedal shaft 178 is pivotally supported by a bracket 182 on the floor 180. Further, in the pedal shaft 178, the accelerator opening degree detecting device 184 generates a signal indicating the accelerator opening A _cc, such as potentiometer is connected. In the figure, reference numeral 186 denotes an accelerator cable or rod, one end of which is connected to the accelerator pedal 176 and the other end is connected to a fuel supply device (not shown), for example, a fuel supply control member of a fuel injection pump, and 188 is a floor 180. The maximum opening of the accelerator pedal 176 (100
It is a stopper that regulates the (% opening). Further, a brake pedal (not shown) for operating the regular brake is arranged on the floor 180 near the driver's seat, and when the driver depresses the brake pedal for decelerating and stopping the vehicle, a signal indicating the pedaling force thereof. B _r is configured to be emitted from a brake pedal force detection device (not shown). When the vehicle is a route bus, a brake system that is power assisted by an air booster is widely used in the regular brake system, so the above-mentioned brake pedal force detection device uses the operating air pressure of the air booster. Alternatively, it is possible to advantageously employ a normal pedaling force detection device that generates a variable electric signal in response to the hydraulic pressure of the brake master cylinder biased by the booster.

The signal indicating the accelerator opening A _cc and the signal indicating the pedal effort B _{r of the} brake pedal are shown in FIG.
Is input to the controller or control device 64 shown schematically in FIG. Further, as shown in the figure, the controller or control device 64 is provided with a rotation speed N _{e of} the engine 10,
Crank angle theta _c of each _cylinder, the running speed V _H of the _vehicle, the variable displacement tilting angle theta _p of tilting plate 82 of the hydraulic pump _30, and accumulator 48 pressure P _a and the pressure oil is reserved in A signal indicating the discharge intake pressure P _s of the supercharger 18 is input respectively.

When the vehicle engine 10 described above is mounted on a route bus, the operation mode of each member according to each state of the traveling mode will be described. (1) First, when the route bus is stopped due to a bus stop or the like and the engine 10 is in idle operation, the accelerator pedal 176 is not depressed, and therefore, the accelerator opening A _cc is zero and the vehicle speed V _H is also It is zero. Also hydraulic pump 3
The tilting angle θ _p of the tilting plate 82 of 0 is zero, and therefore the discharge amount of the pump is also zero. Normally, the pressure accumulator 48 has a set pressure P _ao.
The above high-pressure hydraulic oil is stored, and the second switching valve 50 is closed to prevent the high-pressure hydraulic oil from flowing out. Supercharging is not necessary when the engine 10 is idle,
Since the second switching valve 50 is closed and the amount of oil discharged from the hydraulic pump 30 is zero, the first switching valve 44 may be opened or closed, and the supercharger driving hydraulic motor 20 is stopped. Further, since the engine 10 does not need an output, the above-mentioned intake valve premature closing device is inactive, and the variable orifice or throttle valve 52 further stores the pressure accumulator 48 when the supercharger 18 is driven later.
In order to prevent the pressure oil inside from being temporarily supplied to the hydraulic motor 20 and causing a shock, the opening degree is kept small. Needless to say, the first switching valve 44, the second switching valve 50, the tilt angle control of the tilting plate 82, and the opening degree control of the variable orifice or throttle valve 52 are all output signals of the controller or control device 64. Is based on.

(2) Next, when the route bus starts from the stopped state, the accelerator opening degree _Acc is set to the first set opening degree A.
_{When the vehicle starts} slowly below _cc1 (50% opening as an example) (when it does not start suddenly due to road congestion, etc.), the above-mentioned members and devices maintain the same state as during the idle operation, and the engine 10 is supercharged. Is not performed, and the intake valve early closing device does not operate. In this case, since the accelerator opening A _cc is small and the fuel supply amount is small, there is no problem that the amount of smoke in the exhaust gas increases. In addition, when starting, the accelerator opening A
_cc is the first set opening degree A _cc1 = 50% or more, and the vehicle speed V _H is the first set vehicle speed V _H1 (for example, 40 km / h,
The following until reaching the same) is that if the pressure P _a of the hydraulic oil is reserved in the accumulator 48 is first set pressure P
_{In the case of a1} (190 kg / cm ² as an example) or more, both the first switching valve 44 and the second switching valve 50 are opened by the controller or the control device 64 to supply high-pressure hydraulic oil from the pressure accumulator 48 to the hydraulic motor 20. To be done. At this time, in the variable orifice or throttle valve 52, the discharge intake pressure P _s of the supercharger 18 is appropriately selected within a set pressure P _s0 (for example, in the range of 4 to 12 kg / cm ² ; here, as an example, 10 kg /
The opening is controlled to obtain a pressure oil flow rate such that the pressure oil flow rate becomes cm ² ). The supercharger 18 is driven by the hydraulic motor 20 to supply the pressurized intake air having the pressure P _{s0 to} the engine 10, and the intake air early closing device operates, so that the engine 10 performs the Miller cycle operation with excellent thermal efficiency. At this time, since the high-pressure intake air having the set pressure P _s0 is supplied, the engine 10 can exhibit a high output as described above, and it is possible to reliably prevent an increase in smoke in the exhaust gas. The tilt angle θ _p of the hydraulic pump 30 is controlled to zero by the controller or the control device 64, and thus the discharge oil amount is controlled to zero, so that the output of the engine 10 is not consumed for driving the hydraulic pump 30. , Good acceleration performance is secured.

(3) After starting, the vehicle speed V _H becomes equal to or higher than the first set vehicle speed V _H1 , or the pressure P _a of the pressure oil stored in the pressure accumulator 48 is consumed, and the first set pressure P _H is reached. _a1
The second set opening A that decreases below and the accelerator opening A _{cc at} this time is larger than the first set opening A _cc1 .
_{When it is} less than _cc2 (60% opening by way of example), the controller or control device 64 closes the second switching valve 50 and cuts off the supply of hydraulic oil from the pressure accumulator 48 to the hydraulic motor 20. Since the hydraulic motor 20 stops and supercharging of the engine 10 is stopped, the intake valve premature closing device stops and the Miller cycle operation of the engine 10 is stopped. At the same time, the variable orifice or throttle valve 52 is set to a small opening in order to prevent a shock when the hydraulic motor is operated later. Further, the tilt angle θ _p of the hydraulic pump 30 is still zero, and the discharge amount thereof is zero.

(4) The accelerator opening degree _Acc is the second set opening degree A, whether it is during start-up acceleration or during normal running.
_When it exceeds _cc2 , the tilt angle θ _p of the hydraulic pump 30 is, as shown in the diagram of FIG. 10, an angle θ _pm proportional to the accelerator opening (where θ _pm = K _A × A _cc ; The controller or controller 64 controls K _A to be a constant, and the hydraulic pump 30 discharges high-pressure hydraulic oil in an amount corresponding to the tilt angle θ _pm . At the same time, the first switching valve 44 is opened, the second switching valve 50 is closed, and the hydraulic pump 3
Since substantially the entire amount of the discharged hydraulic oil of 0 is supplied to the hydraulic motor 20, the supercharger 18 is driven and the pressurized intake air is supplied to the engine 10, and the engine 10 reaches the accelerator opening A _cc . Generates a high output according to. Since the second switching valve 50 is closed, the discharge pressure oil of the hydraulic pump 30 is not supplied to the accumulator 48, and the variable orifice or throttle valve 52 has a small opening degree for the same reason as above. It is controlled, and the intake premature closing device is not operating and is at rest. Incidentally, reduced when the engine 10 as described above is traveling supercharging operation, when performing the engine brake running for gradual deceleration, the accelerator opening A _cc or less of course the second set opening A _cc2 As a result, the controller or controller 64 causes the hydraulic pump 30 to rotate the tilt angle θ.
_p is zero, that is, the discharge amount is controlled to zero, the working pressure oil is not supplied to the hydraulic motor 20, and the supercharger 18 is stopped.
The engine 10 shifts to non-supercharged operation.

(5) Further, when the driver decelerates by using the service brake during traveling, the vehicle speed V _H is reduced to the second set vehicle speed V _H2 (as an example, vehicle speed 10 km / h). is the depression of the brake pedal for actuating a service brake, the brake depression force B _r of the pedaling force detecting device
Is output, and the controller or control device 64 controls the tilt angle θ _p of the hydraulic pump 30 based on this signal as follows. That is, as shown in Figure 11 showing the relationship between the tilting angle theta _p of the brake pedal force B _r and the hydraulic pump, pedal force 60% as appropriate settings depression force B _{r1 (an} example from the pressing start of the brake pedal Up to), the tilt angle θ _pn proportional to the brake pedal force B _r (where θ _pn =
K _B × B _r ; K _B is a constant), and the hydraulic pump 30
Discharges high-pressure hydraulic oil in an amount corresponding to the tilt angle θ _pn . At this time, since the first switching valve 44 is closed and the second switching valve 50 is opened by the controller or the control device 64, the pressure oil discharged from the hydraulic pump 30 is not supplied to the hydraulic motor 20, The whole amount is filled in the accumulator 48,
The braking energy of the vehicle is converted into the pressure energy of the hydraulic oil and absorbed. During this time, the variable orifice or throttle valve 52
Is set to a large value to reduce the flow loss of the working oil flowing into the pressure accumulator 48. Of course, since the engine 10 does not need to have a high output, the intake valve early closing device does not operate and is stopped. There is. The above results, the pressure P _a of the pressure oil of the accumulator 48 is set in consideration of the pressure resistance and the like of the above first setting pressure P _a1 second set pressure P _{a2 (accumulator} 48,
As an example, when the pressure is 270 kg / cm ² ) or more, the relief valve 54 opens, and the pressure oil discharged from the hydraulic pump 30 is cooled by the oil cooler 56 and flows back to the oil tank 32.

(6) As a result of the operation of the service brake and the absorption of braking energy by the hydraulic pump 30, the second set vehicle speed V _{H at} which the vehicle speed V _H is sufficiently lower than the first set vehicle speed V _{H1.
When the} vehicle speed V _H becomes less than _H2 (10 km / h as an example) or the vehicle speed V _H is extremely low speed traveling at the second set vehicle speed V _H2 or less due to traffic congestion or the like, the controller or control device 64
As a result, the second switching valve 50 is closed and the hydraulic pump 30
The tilt angle θ _p of the pump is controlled to be zero, so that the pump discharge amount is controlled to be zero. The hydraulic motor 20 includes a hydraulic pump 30 and a pressure accumulator 4.
No pressure oil is supplied from any of No. 8. The first switching valve 44 may be opened or closed, but is controlled to be open, for example, and the variable orifice or the throttle valve 52 is set to a small opening in order to prevent a shock when the supercharger is operated later.
Does not require high power, the intake valve premature closing device does not work.

As described above, in the route bus in the traveling mode in which start and stop are frequently repeated, the braking energy is converted into the pressure energy of the working pressure oil via the variable displacement hydraulic pump 30 and stored in the pressure accumulator 48. , The supercharger 1 by supplying the hydraulic oil in the pressure accumulator 48 to the hydraulic motor 20 when the bus starts.
8 to supply high-pressure intake air to the engine 10 and operate the intake valve early closing device to cause the engine 10 to perform the Miller cycle operation, thereby improving fuel consumption, improving start acceleration, and exhausting gas. A reduction in smoke in the gas can be achieved at the same time. It should be noted that, like the route bus, the present invention can be applied to a vehicle or the like for delivering goods that repeatedly starts and stops frequently, and it is obvious that the same advantages and effects can be obtained.

In the above embodiment, the swash plate type axial piston type hydraulic pump having the tilting plate is illustrated as the variable displacement hydraulic pump. However, instead of the hydraulic pump, a swash shaft type axial pump known per se is used. A piston (or plunger) type hydraulic pump can be adopted. The oblique shaft type hydraulic pump includes a cylinder block support shaft, a cylinder block mounted on the cylinder block support shaft and provided with a plurality of cylinders, a piston or a plunger slidably fitted in the cylinder, A stroke of the piston or the plunger is provided by including a drive shaft operatively connected to the end of the piston or the plunger via a ball joint, and changing the angle formed by the drive shaft and the cylinder block support shaft. Is a high-pressure pump in which the amount of discharged oil is changed. Further, in the above embodiment, the variable displacement hydraulic pump is configured to directly interlock with the crankshaft of the engine via the gear train.
The hydraulic pump may be operatively connected to an appropriate position of a power transmission system such as a transmission so that when the vehicle is braked, it is driven by the running inertia of the vehicle to absorb the braking energy and convert it into pressure energy of pressure oil. it can. Further, it is obvious that an appropriate device other than the illustrated device can be adopted as the intake valve closing timing changing device of the engine, that is, the intake valve early closing device.

[0045]

As described above, a vehicle engine with a braking energy recovery device according to the present invention is provided with an intake valve closing timing changing device capable of changing the opening timing of an intake valve. A positive displacement supercharger driven by a hydraulic motor to supply pressurized air to the engine, and a variable displacement hydraulic pump interposed in a power transmission system of the vehicle and driven by the braking energy of the engine and the vehicle. ,
A main hydraulic circuit connecting the hydraulic oil inlet of the hydraulic motor and the hydraulic oil outlet of the variable displacement hydraulic pump, a branch hydraulic circuit connected to the main hydraulic circuit, and a branch hydraulic circuit interposed in the main hydraulic circuit. A pressure accumulator, a first switching valve provided in a main hydraulic circuit between the branch portion of the branch hydraulic circuit and the hydraulic motor, and a first switching valve provided in a branch hydraulic circuit between the branch portion and the accumulator. It has two switching valves and a control device for opening and closing the first switching valve and the second switching valve according to the operating states of the vehicle and the engine, and effectively controls the amount of smoke during exhaust braking during starting and acceleration. For vehicles suitable for route buses, etc., which can reduce the traveling fuel consumption effectively, absorb a large amount of braking energy, and effectively reduce the burden on the service brake. Engine There is an advantage that may be provided.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an entire vehicle engine showing an embodiment of the present invention.

2 is a sectional view showing an example of a variable displacement hydraulic pump 30 in FIG.

3 is a sectional view taken along the line III-III in FIG. 2 and viewed in the direction of the arrow.

4 is a schematic configuration diagram showing an example of an intake valve closing timing changing device in the vehicle engine of FIG.

5 is a schematic configuration diagram showing a state of the intake valve closing timing changing device shown in FIG. 4 during an intake valve lift.

FIG. 6 is a schematic configuration diagram showing a state of the intake valve closing timing changing device shown in FIG. 4 during an intake valve early closing operation.

7 is a valve lift diagram for explaining the operation of the intake valve closing timing changing device shown in FIG.

FIG. 8 is a P-V diagram when the intake valve closing timing changing device for the vehicle engine shown in FIG. 1 is in operation (intake valve early closing operation).

9 is a side view showing an example of a fuel supply control device including an accelerator pedal of a vehicle equipped with the vehicle engine shown in FIG. 1. FIG.

10 is a diagram showing the relationship between the depression amount (accelerator opening) of the accelerator pedal and the tilt angle (discharge amount) of the variable displacement pump shown in FIG.

11 is a diagram showing a relationship between a brake pedal depression force and a tilt angle of a variable displacement pump when a service brake of a vehicle equipped with the vehicle engine shown in FIG. 1 is operated.

FIG. 12 is a schematic configuration diagram showing a normal configuration of a vehicle engine having a positive displacement supercharger.

[Explanation of symbols]

10 ... Vehicle engine, 12 ... Intake manifold, 14
... Exhaust manifold, 18 ... Positive displacement supercharger, 20 ... Hydraulic pump, 22 ... Crankshaft, 30 ... Variable capacity hydraulic pump, 42 ... Main hydraulic circuit, 44 ... First switching valve, 46 ... Branch hydraulic circuit, 48 ... Accumulator, 50 ... Second switching valve, 52 ... Variable orifice or throttle valve, 54 ... Relief valve, 56 ... Oil cooler, 64 ... Controller (control device), 66 ...
Cylinder block, 68 ... Cylinder, 70 ... Piston or plunger, 82 ... Tilt plate or swash plate, 86 ... Tilt angle control piston, 104 ... Crankcase, 106 ... Cam shaft, 108 ... Intake cam, 122 ... Push rod , 12
6 ... Rocker arm, 130 ... Intake valve stem, 176 ... Accelerator pedal.

Claims (9)

[Claims] 1. A vehicular engine equipped with an intake valve closing timing changing device capable of changing the opening timing of an intake valve, and a positive displacement engine driven by a hydraulic motor to supply pressurized intake air to the engine. A feeder, a variable displacement hydraulic pump interposed in a power transmission system of the vehicle and driven by the braking energy of the engine and the vehicle, an operating oil inlet of the hydraulic motor, and an operating oil discharge port of the variable displacement hydraulic pump. A main hydraulic circuit connecting the main hydraulic circuit, a branch hydraulic circuit connected to the main hydraulic circuit, a pressure accumulator interposed in the branch hydraulic circuit, and a branch portion of the branch hydraulic circuit and the hydraulic motor. The first switching valve provided in the main hydraulic circuit, the second switching valve provided in the branch hydraulic circuit between the branch section and the pressure accumulator, the first switching valve and the second switching valve are provided in the vehicle and the engine. Open and close according to the operating status of An engine for a vehicle with a braking energy recovery device. 2. A swash plate type variable displacement device having a tilting plate, wherein the variable displacement hydraulic pump has a tilting plate capable of controlling an amount of hydraulic oil discharged by controlling a tilting angle formed with respect to a plane perpendicular to the pump shaft. 2. A vehicle engine with a braking energy recovery system according to claim 1, wherein the engine is a hydraulic pump. 3. A variable orifice or throttle valve whose passage area is controlled according to the operating states of the vehicle and the engine is provided in the branch hydraulic circuit between the second switching valve and the pressure accumulator. The vehicle engine with the braking energy recovery device according to claim 1. 4. The amount of hydraulic fluid discharged from the variable displacement hydraulic pump according to the accelerator opening, which represents the amount of fuel supplied to the engine, the pedal effort of the brake pedal for operating the normal brake, and the vehicle speed, The vehicle engine with a braking energy recovery system according to claim 1, wherein the opening / closing of the first switching valve and the second switching valve and the intake valve closing timing changing device are controlled respectively. 5. When the accelerator opening is equal to or greater than a set opening, the vehicle speed is less than a first set vehicle speed, and the hydraulic fluid pressure in the pressure accumulator is equal to or greater than a first set value, the control device controls: Both the first switching valve and the second switching valve are opened to supply the high-pressure hydraulic oil of the pressure accumulator to the hydraulic motor to drive the positive displacement supercharger, and the intake valve closing timing changing device is operated to operate the intake valve. Is closed early.
A vehicle engine with the described braking energy recovery device. 6. When the accelerator opening is equal to or larger than a second preset opening that is larger than the first preset opening,
The variable displacement hydraulic pump is controlled so as to discharge an amount of hydraulic oil that increases in accordance with the accelerator opening, and the first switching valve is opened and the second switching valve is closed, so that the hydraulic pump discharge operation is performed. The engine for a vehicle with a braking energy recovery device according to claim 4, wherein the hydraulic motor is driven by oil and intake air pressurized by the positive displacement supercharger is supplied to the engine. 7. The variable displacement hydraulic pump discharges hydraulic fluid, which increases in accordance with the brake pedal force, by the control device when the vehicle speed is equal to or higher than the second set vehicle speed of the low speed and the brake pedal of the service brake is depressed. And the first switching valve is closed and the second switching valve is opened so that the hydraulic fluid discharged from the hydraulic pump is supplied to the pressure accumulator through the branch hydraulic circuit. An engine for a vehicle with a braking energy recovery device according to claim 4. 8. The discharge intake pressure of the positive displacement supercharger is 4
The vehicle engine with a braking energy recovery device according to claim 5 or 6, characterized in that it is about 12 kg / cm ^{2 and} preferably about 10 kg / cm ² . 9. A positive displacement type driven by a hydraulic motor when the high-pressure hydraulic oil in the pressure accumulator is supplied to the hydraulic motor via the variable orifice or throttle valve, the second switching valve and the first switching valve. The braking energy recovery according to claim 4 or 5, wherein the passage area of the variable orifice or the throttle valve is controlled so that the discharge intake pressure of the supercharger becomes a set pressure. Vehicle engine with device.