JPH06156108A - Output control method for vehicle provided with braking energy regeneration device - Google Patents

Abstract

PURPOSE:To reduce fuel consumption and exhaust gas quantity by limiting an actual maximum fuel quantity of an engine to a maximum fuel quantity in accordance with accumulator pressure when a hydraulic pump/motor is in a motor operation mode. CONSTITUTION:In a vehicle provided with a braking energy regeneration device comprising a hydraulic pump/motor 14, an accumulator 18 and a working liquid tank 20, the hydraulic pump/motor 14 is changed over to a mode of a pump, motor or neutral by a brake pump 22. When the inside of the accumulator 18 is under a high pressure in a motor mode, a motor-time full rack driving quantity becomes a small value in comparison to a normal-time full rack driving quantity at that point of time. As the actual maximum fuel quantity of an engine, a smaller value of a normal-time maximum fuel quantity in accordance with a proper operation state and a motor-time maximum fuel quantity in accordance with pressure of the accumulator 18 is determined by a comparison part. Accordingly, generated torque at that time sufficiently assist output torque of an engine 2 and suppress an actual full rack driving quantity to a small value so as to throttle an actual maximum fuel quantity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an output control method for a vehicle equipped with a pressure-accumulation type braking energy regeneration device.

[0002]

2. Description of the Related Art For example, a route bus provided with a pressure-accumulation type braking energy regeneration device is known. This pressure-accumulation type braking energy regeneration device includes a hydraulic pump / motor, an accumulator and a hydraulic fluid tank. The hydraulic pump / motor is driven as a pump during braking of the vehicle, and the hydraulic fluid in the hydraulic fluid tank is transferred to the accumulator. The accumulator is pressure-accumulated to accumulate pressure. Therefore, in this case, the braking energy of the vehicle is collected as the accumulated energy in the accumulator.

On the other hand, at the time of starting acceleration of the vehicle, the hydraulic pump / motor is driven as a motor by the hydraulic fluid discharged from the accumulator, whereby the hydraulic pump / motor is driven.
The torque generated by the motor assists the driving force of the engine. Therefore, if the above-mentioned braking energy regeneration device is provided in the route bus in which starting and stopping are frequently repeated, the braking energy can be effectively collected and reused, and not only the fuel consumption of the engine can be reduced, but also
It is also an excellent measure against exhaust gas.

[0004]

When the hydraulic pump / motor is driven as a motor, the maximum torque of the motor is the accumulated energy of the accumulator, that is,
The pressure greatly varies. From this fact, when the hydraulic pump / motor is driven in the motor mode while the accumulator is sufficiently accumulating pressure, a large driving torque is applied from the motor to the driving shaft of the vehicle, while
At this time, if the accelerator is depressed greatly and the output of the engine itself is large, an excessive drive torque will be applied to the drive shaft of the vehicle and its differential gear.

The present invention has been made based on the above-mentioned circumstances, and an object thereof is to appropriately limit the amount of fuel to the engine while the hydraulic pump / motor is operating in the motor mode. Accordingly, it is an object of the present invention to provide an output control method for a vehicle that is provided with a braking energy regeneration device that does not give an excessive drive torque to the drive shaft of the vehicle and is excellent in terms of fuel consumption and exhaust gas measures.

[0006]

SUMMARY OF THE INVENTION An output control method according to the present invention is a vehicle equipped with a braking energy regenerative device of the type described above, and when a hydraulic pump / motor operates as a motor, the engine is controlled according to the pressure of an accumulator. The maximum fuel amount for the motor that limits the maximum fuel supply amount of the engine is calculated, and this maximum fuel amount for the motor is compared with the normal maximum fuel amount according to the engine's original operating conditions. Set as the actual maximum fuel amount.

[0007]

According to the above-described output control method, when the vehicle is starting and accelerating, the hydraulic pump / motor is operated in the motor mode, and if the accumulated energy of the accumulator is sufficient at this time, the actual maximum fuel of the engine is The amount is not limited to the normal maximum fuel amount according to the driving condition of the vehicle, but is limited to the motor maximum fuel amount according to the pressure of the accumulator, whereby the output of the engine is suppressed.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1, there is schematically shown an example of a pressure-accumulation type braking energy regenerative device for a route bus. As is well known, the output of the engine 2 is transmitted to the propeller shaft 6 via the transmission 4, and is further transmitted from the propeller shaft 6 to the drive shaft, that is, the drive wheels W via the differential gear 8 to drive the vehicle. It is possible. It

On the other hand, the driving force of the propeller shaft 6 can be transmitted to the hydraulic pump / motor 14 via the differential gear 8, the connecting shaft 10 and the gear box 12. A clutch such as an electromagnetic clutch may be built in the gear box 12 so that the power transmission path between the propeller shaft 6 side and the hydraulic pump / motor 14 can be connected and disconnected.

The hydraulic pump / motor 14 comprises a swash plate type axial plunger type pump, one input / output port of which is provided with a pair of hydraulic accumulators 1 via a switching valve 16.
8 and the other input / output port is the hydraulic oil tank 20.
It is connected to the. The hydraulic accumulator 18 is of a piston type and is capable of storing accumulated energy by utilizing the compressive force of gas.

Although not shown, air pressure from the air tank can be supplied to the hydraulic oil tank 20, and this air pressure keeps the oil level in the hydraulic oil tank 20 at a predetermined pressure. A return pipe is branched from between the hydraulic pump / motor 14 and the switching valve 16. The return pipe is connected to the hydraulic oil tank 20, and a relief valve is inserted in the middle of the return pipe. ing.

The hydraulic pump / motor 14 is connected to a motor-driven control pump 22 for switching its operating mode. The control pump 22 is provided with a directional control valve (not shown) from a drain tank 24. Hydraulic oil is supplied to the hydraulic pump / motor 14 via the swash plate to control the angle of the swash plate, thereby setting the operating mode to any one of the pump mode, the motor mode and the neutral mode.

The drain tank 24 is a hydraulic pump /
The lubricating cooling oil flowing out from the motor 14 is collected, and the operating oil in the hydraulic oil tank 20 is used as the lubricating cooling oil. That is, although not shown, the hydraulic oil in the hydraulic oil tank 20 can be supplied to the hydraulic pump / motor 14 by the hydraulic pump in a different path, and the excess hydraulic oil in the drain tank 24 is It is designed to be returned to the hydraulic oil tank 20 by a motor-driven hydraulic pump 26.

In the case where each of the pumps, the switching valve 16 and the gear box 12 described above is provided with a clutch, these clutches are included in the control signal from the control unit 28 according to the driving operation of the vehicle. Due to
Its operation is controlled. Therefore, the control unit 28 is electrically connected to the accelerator switch 30 and the brake switch 32, and the accelerator signal and the brake signal can be supplied to the control unit 28 from these switches.

Now, when the control unit 28 receives a brake signal from the brake switch 32 while the vehicle is traveling, the control unit 28 drives the control pump 22 and activates the direction control before the service brake of the vehicle is activated. It controls valve switching and drives the swashplate of the hydraulic pump / motor 14 to switch its operating mode from neutral to pump mode. Therefore, when the hydraulic pump / motor 14 is driven as a pump, the hydraulic oil in the hydraulic oil tank 20 is then pumped to the pair of accumulators 18 through the switching valve 16 in the pressure accumulation position,
Accumulation of pressure in these accumulators 18 is executed. That is, the braking energy of the vehicle is stored in the accumulator 18 as accumulated energy.

When the discharge pressure from the hydraulic pump / motor 14 reaches or exceeds a predetermined pressure, the relief valve is opened and the working oil is returned to the working oil tank 20 through the return pipe line. It goes without saying that the operation mode of the hydraulic pump / motor 14 is switched from the pump mode to the neutral mode when the braking of the vehicle is completed or interrupted.

On the other hand, when it is detected by the accelerator signal from the control unit 28 or the accelerator switch 30 that the vehicle is starting to accelerate, the control unit 28 switches the switching valve 16 from the pressure accumulation position to the delivery position, and , The control pump 22 and the directional control valve,
The operation mode of the hydraulic pump / motor 16 is switched from the neutral mode to the motor mode. Therefore, at this time, the hydraulic pump / motor 14 is operated by the hydraulic oil sent from the paired hydraulic accumulator 18 through the switching valve 16.
Is driven as a motor and generates torque according to the pressure in the hydraulic accumulator 18. This torque is transmitted to the drive shaft of the vehicle and assists the output torque of the engine. As a result, the vehicle is started and accelerated by the power of both the engine and the hydraulic pump / motor 14, and the fuel consumption of the engine and the amount of exhaust gas can be reduced.

After that, the pair of hydraulic accumulators 1 is operated when the vehicle shifts to steady running or when hydraulic oil is sent out.
When the piston of 8 reaches the end position of its stroke,
The operation mode of the hydraulic pump / motor 14 is switched from the motor mode to the neutral mode. An end detection sensor (not shown) is incorporated in one of the hydraulic accumulators 18 at its end position, and this end detection sensor outputs a detection signal thereof when the piston reaches the end position. Output to. Also,
Needless to say, in addition to the accelerator signal, the gear position of the transmission and the allowance of the clutch pedal are taken into consideration in detecting whether the vehicle is starting or accelerating. .

On the other hand, as is well known, the output torque of the engine 2 is controlled by adjusting the supply amount of fuel discharged from the fuel injection pump 34 toward the engine 2, that is, the fuel amount. That is, in the case where the fuel injection pump 34 is of the row type as shown in the drawing and has the electronic governor 36, when the target rack drive amount Ro is given from the governor controller 38 to the electronic governor 36, the electronic governor 36 becomes The actual rack drive position of the control rack (not shown) in the fuel injection pump 34 is driven toward the target rack drive amount Ro, and the discharge amount of the fuel injection pump 34, that is, the engine 2
The fuel amount of.

More specifically, the governor controller 38
Includes a speed sensor 40 for detecting the engine speed Ne,
An accelerator opening sensor 42 that detects an opening A of the accelerator pedal is electrically connected, and the governor controller 3 is based on sensor signals from these sensors, that is, detection values.
8 calculates the target rack drive amount. On the other hand, in this embodiment, the governor controller 38 can receive the full rack variable signal FSW and the full rack instruction voltage V from the control unit 28. The full rack variable signal FSW is used when the hydraulic pump / motor 14 is switched to the motor mode.
8 is supplied to the governor controller 38, and the full rack instruction voltage V has a value corresponding to the amount of energy accumulated in the accumulator 18 as a control unit 28.
Is supplied to the governor controller 38.

Therefore, as shown in FIG. 1, a pressure sensor 44 for detecting the pressure in the hydraulic accumulator 18 is electrically connected to the control unit 28, and the control unit 28 has a pressure sensor 44. A full rack instruction voltage V that is inversely proportional to the pressure signal from the controller is generated and supplied to the governor controller 38. FIG. 2 is a block diagram showing a procedure for calculating the target rack drive amount executed by the governor controller 38 based on the engine speed Ne, the accelerator opening A, the full rack variable signal FSW and the full rack instruction voltage V. Has been done.

As is apparent from the block diagram, the engine speed Ne and the accelerator opening A are supplied to the running rack setting section 46, and the running rack setting section 46 obtains the running rack drive amount RD. . That is, the running rack setting unit 46 has a map as shown in FIG. 3, and this map has different characteristic curves according to the accelerator opening A, and the engine speed is calculated from each characteristic curve. The traveling rack drive amount RD is obtained based on Ne. As is clear from the characteristic curves, at each accelerator opening A, the running rack drive amount RD decreases as the engine speed Ne increases, and the engine speed Ne remains the same. In some cases, the rack drive amount RD for traveling increases as the accelerator opening A increases.

In the fuel injection pump 34, as the target rack drive amount, that is, the running rack drive amount RD increases, the fuel discharge amount, that is, the fuel amount to the engine 2 increases. On the other hand, the engine speed Ne is
It is also supplied to the engine's original normal full rack setting unit 48.
The normal full rack drive amount RDF is set based on the engine speed Ne from the map shown in FIG. The normal full rack drive amount RDF is a value that limits the maximum drive amount of the control rack in the fuel injection pump 34, that is, the maximum injection amount. As is clear from the map of FIG. 4, the normal full rack drive amount RDF is maintained constant when the engine speed Ne is in the low speed range, and the engine speed N in the process of shifting from the low speed range to the middle speed range.
It keeps constant after gradually decreasing as e rises,
Then, from the middle speed range to the high speed range, it has a characteristic that it gradually decreases as the engine speed Ne rises. Therefore, the characteristics of the map of FIG. It has a tendency to follow the characteristic curve.

On the other hand, the full rack instruction voltage V from the control unit 28 is set to the motor full rack setting section 50.
Is supplied to the full rack setting unit 50 for this motor.
Then, the motor full rack drive amount RMD is set based on the full rack instruction voltage V from the map as shown in FIG. This motor full rack drive amount RMD limits the maximum injection amount of the fuel injection pump 34 when the hydraulic pump / motor 14 is in the motor mode, and as is clear from FIG. As V rises,
That is, it has a characteristic that it increases as the accumulated pressure value in the hydraulic accumulator 18 decreases.

Normal rack and motor full rack setting section 4
The outputs from 8 and 50 are supplied to the comparison unit 52, which outputs the normal rack and motor full rack drive amount RD.
The smaller one of F and RMF is supplied to one contact of the variable switch 54. In addition, the normal full rack setting section 48
Also supplies the full rack drive amount RDF to the other contact of the variable switch 54 at the normal time.

The movable contact of the variable switch 5 is switched by the above-mentioned full rack variable signal FSW from the control unit 28. When there is no full rack variable signal FSW, the movable contact is shown in the figure. Thus, the state of being connected to the other contact is maintained.
The outputs of the variable switch 54 and the running rack setting unit 46 are both supplied to the comparison unit 56, and this comparison unit 56, like the comparison unit 54, has the smaller input, that is,
Either the running rack drive amount RD or the input from the comparison unit 54 is set as the target rack drive amount RO to the electronic governor 3
Supply to 6.

Now, when the vehicle is running and the hydraulic pump / motor 14 is in the neutral mode or the pump mode, the control unit 28 operates as the governor controller 3.
8 does not output the full rack variable signal FSW, so the variable switch 54 is in the switching position shown. In such a situation, the running rack setting unit 4
6 and the output from the normal time rack setting unit 48, that is, the running rack drive amount RD and the normal full rack drive amount RDF are supplied to the comparison unit 56, and the comparison unit 56 determines the rack drive amount RD. , RDF, whichever is smaller, is supplied to the electronic governor 36 as the target rack drive amount RO. Therefore, in this case, the governor controller 38 calculates the target rack drive amount RO according to a normal procedure, that is, the original engine control procedure, and then calculates the target rack drive amount R0.
Based on O, the fuel amount of the engine 2 is controlled via the electronic governor 36.

On the other hand, when the vehicle starts or accelerates,
The control unit 28 is a full rack variable signal FS.
W is supplied to the governor controller 38, whereby the variable switch 54 of the governor controller 38 is switched from the illustrated state to the other switching position. In this case, since the comparison unit 52 works effectively, the comparison unit 54 has the output from the comparison unit 52, that is, the normal full rack drive amount RDF and the motor full rack drive amount in addition to the running rack drive amount RD. Since the smaller one of the RMFs is supplied, the comparison unit 54 outputs the smallest of the running rack drive amount RD, the normal full rack drive amount RDF, and the motor full rack drive amount RMF from the target rack drive amount. The quantity RO is supplied to the electronic governor 36.

Here, as is clear by comparing the characteristics of FIG. 4 and FIG. 5, it is clear that at the time of vehicle start acceleration, sufficient pressure is accumulated in the hydraulic accumulator 18 and the pressure is high, that is, When the full rack command voltage V is small, the motor full rack drive amount RMF takes a smaller value than the normal full rack drive amount RDF at that time. Therefore, the target rack drive amount RO from the comparison unit 54 is , The smaller value of the running rack drive amount RD and the motor full rack drive amount RMF.

Therefore, if the hydraulic pump / motor 14 is in the motor mode and the pressure in the accumulator 18 is high at this time, the torque generated by the hydraulic pump / motor 14 can sufficiently assist the output torque of the engine 2. Therefore, in such a situation, the full rack drive amount RMF for the motor is adopted as the full rack drive amount, and the actual full rack drive amount is suppressed to a small value, so that the actual maximum injection amount of the fuel injection pump 34 is reduced. That is, the actual maximum amount of fuel that can be supplied to the engine 2 can be narrowed down as compared with the normal case.

As a result, when the vehicle starts to accelerate, the engine 2
Output torque can be prevented from becoming unnecessarily large, and the load on the drive shaft of the vehicle, the differential gear 8 and the like can be reduced, and in this case, the fuel consumption of the engine 2 can be small, The fuel consumption and the amount of exhaust gas can also be effectively reduced, and further, the graphite in the exhaust gas can be reduced.

In the embodiment described above, since the variable switch 54 is added to the governor controller 38, the variable switch 54 is maintained in the normal switching position even if an abnormality occurs in the control unit 28, for example. The target rack drive amount RO to the electronic governor 36 does not become undesirably small, and the fuel amount of the engine 2, that is, the output torque of the engine 2 does not become insufficient.

FIG. 6 is a flowchart showing the procedure for calculating the target rack drive amount R 0 described with reference to the block diagram of FIG. 2. However, in order to avoid duplication of description, the flowchart will be described below. Briefly explained. Target rack drive amount calculation routine First, step S
In 1, the engine speed Ne, the accelerator opening A, the full rack command voltage V, and the full rack variable signal FSW are read, and the running rack drive amount RD and the normal full rack are read based on Ne, A, and V. The drive amount RDF and the motor full rack drive amount RMF are obtained (step S2).

Thereafter, in step S3, it is determined whether or not the full rack variable signal FSW is ON, that is, the hydraulic pump /
It is determined whether or not the motor 14 is switched to the motor mode. If the determination result is no, the rack switch during traveling is driven with the variable switch 54 maintained in the illustrated switching position, that is, in the OFF position (step S4). The smaller one of the amount RD and the normal full rack drive amount RDF is selected, and the selected one is output as the target rack drive amount RO (step S5).

On the other hand, if the result of the determination in step S3 is positive, the variable switch 54 is turned on (step S6), the running rack drive amount RD, the normal full rack drive amount RDF and the motor full rack drive are set. The smallest of the quantities RMF is selected, and the selected one is output as the target rack drive quantity RO (step S7). The present invention is not limited to the above-described embodiment, and various modifications can be made. For example, in one embodiment, the control unit 28 and the governor controller 38 are separately provided. It is also possible to make these into one unit. Further, in the embodiment, the fuel injection pump 34 is of the column type, but it may be a distribution type fuel injection pump, and further, the maps shown in FIGS. The above description roughly shows the characteristics of the rack drive amount for explaining the above, and is not necessarily limited to the characteristics of these maps.

[0036]

As described above, according to the vehicle output control method of the present invention, in a vehicle equipped with a braking energy regeneration device, when the hydraulic pump / motor of the braking energy regeneration device operates as a motor, the engine is essentially The maximum fuel amount during normal operation according to the operating conditions of the engine is compared with the maximum fuel amount during motor that limits the fuel supply amount of the engine according to the pressure of the accumulator, and the smaller one of these is the actual maximum fuel amount for the engine. Since I set it as the fuel amount,
When the pressure in the accumulator is sufficient, it is possible to limit the actual maximum fuel amount of the engine to the motor maximum fuel amount in consideration of the large torque generated by the hydraulic pump / motor. Therefore, in the situation where the generated torque of the hydraulic pump / motor, that is, the assist torque is sufficiently obtained at the time of starting acceleration of the vehicle, the actual maximum fuel amount to the engine, that is, the output torque is effectively limited, It has advantages such as reduction in fuel consumption and exhaust gas amount.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an entire energy regeneration device including a fuel control device.

FIG. 2 is a block diagram showing a procedure for calculating a target rack drive amount supplied to the electronic governor from the governor controller in FIG.

FIG. 3 is a diagram showing a map for setting a traveling rack drive amount from an engine speed and an accelerator opening.

FIG. 4 is a view showing a map for setting a normal full rack drive amount from an engine speed.

5 is a diagram showing a map for setting a motor full rack drive amount with respect to a full rack instruction voltage from the control unit of FIG.

FIG. 6 is a flowchart showing a target rack drive amount calculation routine executed in the block diagram of FIG.

[Explanation of symbols]

 2 engine 4 transmission 10 differential gear 14 hydraulic pump / motor 16 switching valve 18 hydraulic accumulator 20 hydraulic oil tank 28 control unit 30 accelerator switch 32 brake switch 34 fuel injection pump 36 electronic governor 38 governor controller 40 speed sensor 42 accelerator opening sensor 44 Pressure sensor

Claims (1)

[Claims] 1. A hydraulic pump / motor, an accumulator, and a hydraulic fluid tank, wherein the hydraulic pump / motor works as a pump during braking, the hydraulic fluid in the hydraulic fluid tank is pumped to an accumulator, and braking energy is stored in the accumulator. In the vehicle equipped with a braking energy regeneration device that assists the driving force of the engine by causing the hydraulic pump / motor to act as a motor by the hydraulic fluid sent from the accumulator during start acceleration, When the pump / motor operates as a motor,
The maximum fuel amount in the motor for limiting the fuel supply amount to the engine is obtained according to the pressure of the accumulator, and the smaller of the maximum fuel amount in the motor and the normal maximum fuel amount according to the original operating condition of the engine. A method for controlling the output of a vehicle having a braking energy regeneration device, characterized in that one of them is set as an actual maximum fuel amount of the engine.