JPH06156103A - Control device for four-wheel traveling device - Google Patents

Abstract

PURPOSE:To maximize front wheel drive force so as to conduct traveling by only front wheels. CONSTITUTION:A change-over switch 32 is provided for selecting a normal time traveling mode and an abnormal time traveling mode of a main controller 23. When the main controller 23 is in the normal time traveling mode, displacement of a variable displacement hydraulic pump and a variable displacement hydraulic motor is controlled according to rear wheel rotation speed. When the main controller 23 is in the abnormal time traveling mode and a transmission neutral signal is inputted, the displacement of the variable displacement hydraulic pump and the variable displacement hydraulic motor is maximized to drive front wheels 2 with maximum torque.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for a four-wheel traveling device for a traveling vehicle such as a large dump truck for construction machinery.

[0002]

2. Description of the Related Art As a four-wheel traveling system for a traveling vehicle, as shown in, for example, Japanese Patent Laid-Open No. 63-258223, the output power of the engine is mechanically transmitted to the rear wheels via a transmission, and the engine is There is known a four-wheel drive traveling device that combines a mechanical drive type and a hydraulic drive type in which a front wheel is driven by a variable hydraulic motor that is driven by discharge hydraulic fluid of the variable hydraulic pump. ing.

[0003]

Such a four-wheel traveling device is a four-wheel traveling system in which the capacities of the variable hydraulic pump and the variable hydraulic motor are controlled to synchronize the rotational speeds of the front wheels and the rear wheels. The capacities of the variable hydraulic pump and the variable hydraulic motor are controlled by the rear wheel rotation speed.

In the above-described four-wheel drive system, when an abnormality or failure occurs in the mechanical transmission device that mechanically connects the engine and the rear wheels, for example, the torque converter, the transmission is broken, the power transmission shaft is dropped or damaged. The rear wheels cannot be driven by the engine when a failure of the differential gear occurs.

In this case, since the displacements of the variable hydraulic pump and the variable hydraulic motor cannot be controlled, the front wheels cannot be hydraulically driven and the traveling vehicle cannot travel.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a control device for a four-wheel traveling device that can solve the above-mentioned problems.

[0007]

An output side of an engine 7 is connected to a rear wheel 3 via a mechanical transmission device including a transmission 9 and the like, and a variable hydraulic motor 13 for driving a front wheel 2 and an engine 7 are connected.
In the four-wheel traveling device in which the variable hydraulic pump 15 driven by the variable hydraulic pump 15 is provided, and the variable hydraulic pump 15 and the variable hydraulic motor 13 are connected in a circuit, a means for controlling the capacity of the variable hydraulic pump 15 and the variable hydraulic motor 13 are provided. A means for controlling the capacity, a main controller 23 having a normal traveling mode and an abnormal traveling mode, and a mode changeover switch 32 are provided. In the normal traveling mode, the main controller 23 is provided.
Controls the capacities of the variable hydraulic pump 15 and the variable hydraulic motor 13 according to the rear wheel rotation speed, and when the transmission neutral signal is input during the abnormal running mode, the main controller 23 causes the variable hydraulic pump 15 and the variable hydraulic pressure to change. A control device for a four-wheeled traveling device configured to maximize the capacity of the motor 13.

[0008]

[Operation] When the abnormal running mode is set by the mode changeover switch 32 and the transmission 9 is set to the neutral position, the capacities of the variable hydraulic pump 15 and the variable hydraulic motor 13 become maximum, and the variable hydraulic motor 13 outputs maximum torque. , Front wheel 2
Can be driven with the maximum driving force, and when the mechanical transmission device that connects the engine 7 and the rear wheels 3 is abnormal and the rear wheels 3 cannot be driven, the variable hydraulic motor 13 and the variable hydraulic pump 15 can be used to travel with the maximum traction force.

[0009]

[Example] As shown in FIG. 1, a pair of left and right front wheels 2 and a pair of left and right rear wheels 3 are attached to the front and rear portions of a vehicle body 1, and a cab 4 is provided in the front portion of the vehicle body 1. , Car body 1
A body 5 is attached to a rear portion of the hoist cylinder 6 so that the body 5 can be raised and lowered to form a large dump truck for construction machinery. The output side of the engine 7 attached to the front part of the vehicle body 1 is connected to a pair of left and right rear wheels 3 via a mechanical transmission device such as a torque converter 8, a transmission 9, a power transmission shaft 10, a differential gear 11, and the like. The wheel 3 is mechanically driven by the engine 7.

As shown in FIG. 2, the front wheel 2 is rotatably supported by an arm 12 which is swingably supported on the vehicle body, and a forward / reverse variable hydraulic motor 13 is attached to the arm 12. The output side of the variable hydraulic motor 13 is connected to the front wheels 2 via the clutch 14, and the discharge hydraulic fluid of the variable hydraulic pump 15 driven by the engine 7 is the first.
It is supplied to the variable hydraulic motor 13 by the second main circuits 16 and 17. The variable hydraulic pump 15 can reverse the discharge direction.

As shown in FIG. 2, the rotation speed of the engine 7 is detected by the engine rotation sensor 18, the input shaft rotation speed of the transmission 9 is detected by the input shaft rotation sensor 19, and the speed stage of the transmission 9 is the speed. The step detection sensor 20 detects the first
The oil pressures of the second main circuits 16 and 17 are detected by the first and second pressure sensors 21 and 22, and the detected values are input to the main controller 23, and the main controller 23 receives the engine speed from the accelerator sensor 24. Control signal, brake signal from brake sensor 25, retarder brake signal from retarder sensor 26, four-wheel drive signal from changeover switch 27, two-wheel drive signal, steering angle signal from steering angle sensor 28, front wheel rotation speed signal from front wheel rotation sensor 29 Are input respectively.

The clutch 14 is of a hydraulically operated type so that it is turned on when pressure oil is supplied to the pressure receiving chamber 14a and turned off when the pressure oil is discharged to the tank. The clutch switching valve 30 is provided in the pressure receiving chamber 14a by a torque converter. The discharge pressure oil of the auxiliary hydraulic pump 31 such as a charge pump is supplied, and the clutch switching valve 30 is switched from the drain position a to the supply position b by energizing the solenoid 30a.

The variable hydraulic motor 13 and the variable hydraulic pump 15 are provided with a capacity control member 40 as shown in FIG. 3, and the capacity control member 40 is operated in the forward and reverse directions by a cylinder 41 to control the capacity in the forward and reverse directions. The hydraulic fluid discharged from the control hydraulic pump 42 is supplied to the cylinder 41 by the solenoid proportional valve 43, and the first and second solenoids 43a and 43b of each solenoid proportional valve 43 are electrically operated by the main controller 23. Output a signal.

For example, when the first solenoid 43a is energized, the capacity control member 40 operates in the forward direction, the variable hydraulic pump 15 discharges pressure oil to the first main circuit 16, and the variable hydraulic motor 13 rotates in the normal direction. When the second solenoid 43b is energized, the capacity control member 40 operates in the reverse direction, the variable hydraulic pump 15 discharges pressure oil to the second main circuit 16, the variable hydraulic motor 13 rotates in the reverse direction, and the capacities are the first and second. Solenoid 43a,
It is proportional to the amount of electricity supplied to 43b.

The main controller 23 has a normal running mode 23a and an abnormal running mode 23b. When the normal running mode signal is input from the mode changeover switch 32, the normal running mode is entered and the abnormal running mode signal is input. Then, the traveling mode at the time of abnormality is set.

Next, the traveling control operation in the abnormal traveling mode will be described. When the transmission 9 is operated to the neutral position after the abnormal running mode 23b is selected by the mode changeover switch 32, the transmission neutral signal is input from the speed stage detection sensor 20 to the main controller 23. This transmission neutral signal may be input to the main controller 23 from the shift operation lever.
As a result, the main controller 23 causes the variable hydraulic pump 15 to
Of the solenoid proportional valve 43 is energized to maximize the capacity, and the first solenoid 43a of the solenoid valve 43 of the variable displacement motor 13 is energized to maximize the capacity, and the clutch is switched. Solenoid 30 of valve 30
A is energized to connect the clutch 14 at the supply position a.

As a result, the discharge amount per one rotation of the variable hydraulic pump 15 is maximized, the discharge amount per unit time is maximized, the flow rate per revolution of the variable hydraulic motor 13 is maximized, and the output torque is maximized. Therefore, the front wheel driving force becomes maximum and the vehicle can travel only by the front wheels 2, and the traction force at that time becomes maximum. This operation is shown in FIG. 4, which is a flow chart.

Because of this, the variable hydraulic pump 15 and the variable hydraulic motor 13 are in the abnormal state of the mechanical transmission device such as the failure of the torque converter 8 and the transmission 9, the dropout or damage of the power transmission shaft 10, the failure of the differential gear 11, and the like. You can run with maximum traction using.

Next, an example of the traveling control operation when the ordinary traveling mode 23a is selected with the mode changeover switch 32 set to the ordinary traveling mode position will be described, but the present invention is not limited to this traveling control operation.

When the changeover switch 27 is turned off and a two-wheel drive signal is input to the main controller 23. (Step 100 in FIG. 5) The clutch switching valve 30 is set to the drain position a and the clutch 14 is disengaged so that the front wheels 2 rotate freely with respect to the variable hydraulic motor 13. At the same time, the variable hydraulic pump 1 is rotated.
The solenoid proportional valve 43 of No. 5 is set to the neutral position and the capacity is set to zero. As a result, the output of the engine 7 is transmitted from the transmission 9 to the rear wheels 3 for mechanical drive.

When the changeover switch 27 is turned on and a four-wheel drive signal is input to the main controller 23. (Step 100 in FIG. 5) Proceeding to step 101 in FIG. 5, the abnormality of the hydraulic drive system is judged, and when there is an abnormality, the abnormality is notified, the capacity of the variable hydraulic pump is set to zero, and the clutch 14 is disengaged. When there is no abnormality, the routine proceeds to step 102, where rear wheel slip is determined.

In step 102, it is determined whether the rear wheel 3 is slipping. If not, the front wheel 2 is slipped.
The driving force for the front wheels 2 is increased when the vehicle is slipping. That is, when the rear wheels 3 are not slipping, the rear wheel driving force can be sufficiently traveled, so that the driving force of the front wheels 2 is reduced to reduce the horsepower consumption of the variable hydraulic pump 15 to reduce the power loss of the engine. When the car is slipping, the front wheel 2
The driving force is increased to drive four wheels.

Next, the slip determination of the rear wheel 3 will be described. The main controller 23 calculates the front wheel rotation speed from the front wheel rotation speed signal from the front wheel rotation sensor 29, and the rear wheel is calculated from the input shaft rotation speed signal of the input shaft rotation sensor 19 of the transmission 9 and the speed gear signal of the speed gear detection sensor 20. Calculate the rotation speed,
The value obtained by dividing the front wheel rotation speed by the rear wheel rotation speed is within a certain range of 1 or more (for example, 1.1) and for a predetermined time (for example, 0.
1 second) When it continues, it is judged that it is a rear wheel slip, and when the value obtained by dividing the front wheel rotation speed by the rear wheel rotation speed is 1 or less, it is judged that it is not a rear wheel slip.

The above description is for the case of straight traveling, and in the case of turning traveling, the front wheels 2 rotate faster than the rear wheels 3, and the rotation speed ratio thereof changes depending on the steering angle. Determine wheel slip. In other words, half of the sum of the rotational speed F _R of the rotation speed F _L and the right front wheel 2 of the left front wheel 2 and a front wheel rotational speed, the main controller 23 previously stores a rotational speed ratio of front and rear wheels by the turning radius (steering angle) Let
The turning radius at that time is calculated by the steering angle signal from the steering angle sensor 28, the rotation speed ratio corresponding to the turning radius is read as a correction coefficient α, and the correction coefficient α is multiplied by the front wheel rotation speed to rotate the front wheels for comparison. As the speed, the rear wheel slip is determined in the same manner as described above by the front wheel rotation speed and the rear wheel rotation speed for comparison.

Next, the magnitude of the driving force of the front wheels will be described. Variable hydraulic pump 1 to reduce the driving force of front wheels 2
The discharge pressure of 5, that is, the pressure of the first or second main circuit 16, 17 is set to a low pressure. This allows the variable hydraulic motor 1
Since the pressure of the oil supplied to 3 becomes low, the driving torque of the variable hydraulic motor 13 becomes small and the driving force of the front wheels becomes small.

In order to increase the driving force of the front wheels 2, the discharge pressure of the variable hydraulic pump 15, that is, the first or second main circuit 16,
Set the pressure at 17 to high pressure. As a result, the pressure of the oil supplied to the variable hydraulic motor 13 becomes high, so that the driving torque of the variable hydraulic motor 13 becomes large and the driving force of the front wheels becomes large.

Specifically, a low pressure and a high pressure are stored in the main controller 23. When the rear wheels are not slipping, the low pressure is the set pressure, and when the rear wheels are slipping, the high pressure is the set pressure.

After the front wheel driving force is set as described above, the target displacement of the variable hydraulic pump 15 is determined according to the front wheel driving force, that is, the set pressure, and the main controller 23 controls the first solenoid 43a of the solenoid proportional valve 43. Energize to set the variable hydraulic pump to the target capacity. Specifically, the main controller 23 stores the capacity of the variable hydraulic pump 15 corresponding to the set pressure of the low pressure and the high pressure, and the main controller 23 stores the capacity of the variable hydraulic pump by the low pressure and the high pressure set as described above. To output a current to the first solenoid 43a of the solenoid proportional valve 43 to set the capacity.

Next, at step 103, it is judged whether the pressure of the variable hydraulic pump 15 is the set pressure, and if it is the set pressure, the capacity of the variable hydraulic motor 13 is controlled according to the vehicle speed.
If it is not the set pressure, the capacity of the variable hydraulic pump 15 is controlled to correct it to the set pressure. Specifically, the main controller 23 detects the pressure of the first main circuit 16 by the first pressure sensor 21, and increases the amount of electricity supplied to the first solenoid 43a of the solenoid proportional valve 43 when the pressure is lower than the set pressure. Then, the capacity of the variable hydraulic pump 15 is increased, and when the capacity is high, the amount of electricity supplied to the first solenoid 43a of the solenoid proportional valve 43 is reduced to decrease the capacity of the variable hydraulic pump 15.

By controlling the capacity of the variable hydraulic motor 13 described above by the vehicle speed (transmission speed stage), the rotational speed of the front wheels 2 can be set to a value corresponding to the vehicle speed even if the capacity of the variable hydraulic pump 15 is constant. For example, when the transmission 9 is in the first gear, the amount of electricity to the first solenoid 43a of the solenoid proportional valve 43 is set to be large, the capacity of the variable hydraulic motor 13 is set to be large, and the variable hydraulic motor 13 is rotated at a low speed. When the amount of electricity supplied to the first solenoid 43a of the solenoid proportional valve 43 is set to medium and the volume is set to medium, the medium speed rotation is performed. High speed rotation. That is, the capacity of the variable hydraulic motor 13 is the flow rate for one rotation, and is 1 if the capacity is large.
Since the flow rate during rotation increases, the rotational speed changes by changing the capacity even if the discharge flow rate of the variable hydraulic pump 15 is constant, and the front wheel rotation speed becomes a value commensurate with the vehicle speed (rear wheel rotation speed).

As described above, when the capacity of the variable hydraulic motor is controlled according to the vehicle speed, the clutch 140 is engaged and the four-wheel drive is performed. The conditions under which the clutch 14 is in contact are that the same speed stage is continuous for 1.3 seconds or more, the engine speed is a specified value (1070 rpm) or more, and from the direct connection clutch ON signal of the torque converter 8, 1. Two seconds have passed, the torque converter mode is maintained, and the speed stage is either a low speed stage or reverse. If these are satisfied, the main controller 23 supplies a current to the solenoid 30a of the clutch switching valve 30 by supplying current. Clutch 14 as position a
When pressure oil is supplied to the pressure receiving chamber 14a of the above, the clutch 14 is brought into contact, and when one condition is not satisfied, the clutch 14 is turned off. The operation of engaging the clutch 14 is actually different from the flow chart shown in FIG. 4 described above, and is shown in FIG. 4 for convenience of explanation.

Next, setting of the target capacity of the variable hydraulic pump 15 will be described. As described above, by setting the capacity of the variable hydraulic motor 13 according to the speed stage and rotating the variable hydraulic motor 13 with the capacity of the variable hydraulic pump 15 being constant, the rotation speed of the front wheels 2 is made larger than that of the rear wheels 3. The target displacement of the variable hydraulic pump 15 is determined in consideration of not only the bit pressure but also the reduction ratio of the torque converter 8 because the four-wheel drive is performed slightly faster. That is, the variable hydraulic motor 15 is driven by the engine 7, and the engine output is transmitted to the rear wheels 3 via the torque converter 8. Therefore, if the reduction ratio of the torque converter 8 is different, the rear wheels 3 are not rotated even if the engine speed is constant. As a result, the front wheel 2 and the rear wheel 3 cannot rotate in synchronization with each other due to the change in the rotation speed of the above.

To this end, the reduction ratio of the torque converter is calculated by the following equation based on the engine speed signal input to the main controller 23 and the transmission input shaft speed. Reduction ratio = engine rotation speed / transmission input shaft rotation speed The target displacement of the variable hydraulic pump 15 is corrected by the calculated reduction gear so that the actual displacement of the variable hydraulic pump 15 becomes a value according to the reduction ratio of the torque converter. . As a result, the front wheels 2 and the rear wheels 3 can be synchronously rotated as described above.

Since it is important to rotate the front wheels 2 at a higher speed during turning traveling than when traveling straight ahead, it is important for smooth turning, so the target displacement of the variable hydraulic pump 15 is corrected by the steering angle. Specifically, the steering angle (turning radius) is known from the steering angle signal input to the main controller 23, the target displacement of the variable hydraulic pump 15 is increased in proportion to the magnitude of the steering angle, and it is proportional to the steering angle. The variable hydraulic motor 13 is rotated at a higher speed than when the vehicle is traveling straight, and the front wheels 2 are rotated faster. The amount by which the target displacement of the variable hydraulic pump 15 is increased is determined by the axial distance between the front wheels 2 and the rear wheels 3 and the like.

Next, the setting of the front wheel driving force after the rear wheel slip determination will be described. Although the front wheel driving force is set to be large or small as described above, the operating condition of the off-road dump truck changes greatly. Therefore, in order to efficiently drive the four wheels, it is necessary to set it in multiple stages according to the operating condition as follows. did.

(1) When the rear wheel 3 is not slipping.
(When front wheel driving force is small) When the body 5 is not loaded with earth and sand (hereinafter referred to as an empty vehicle), the set pressure is set to 30 to 150 kg / cm ² . When sediment is loaded on the body 5 (hereinafter referred to as loading), the set pressure is set to 50 to 200 kg / cm ² . The set pressure is 100 to 250 kg / cm ² when the vehicle is empty. The setting pressure is 125 to 380 kg / cm ² when the vehicle starts to slope.

(2) When the rear wheel 3 is slipping. (When the front wheel driving force is large) The set pressure is set to 80 to 300 kg / cm ² when the vehicle is empty. When loaded, the set pressure is 100-350 kg / cm ² . The set pressure is 200 to 380 kg / cm ² when the vehicle is empty. The setting pressure is 300 to 380 kg / cm ² when the vehicle starts to climb
And Each of the above set pressures is the pressure of the first main circuit 16, that is, the high pressure side, and the pressure of the second main circuit 17, which is the low pressure side, is 25 kg / cm ² .

Next, a case where the variable hydraulic pump 15 and the variable hydraulic motor 13 are used as a brake will be described. Since a large dump truck has a heavy vehicle weight, braking with a brake and a retarder brake may not be sufficient. Therefore, the variable hydraulic pump 15 and the variable hydraulic motor 13 provided for four-wheel drive are used as brakes. .

The details will be described below. When a brake signal or a retarder brake signal is input to the main controller 23, the main controller 23 causes the first proportional solenoid valve 43
The capacity of the variable hydraulic pump 15 is made significantly smaller than the target capacity by reducing the amount of electricity supplied to the solenoid 43a. As a result, the flow rate supplied to the variable hydraulic motor 13 becomes less than the flow rate for rotating the front wheels 2, and the front wheels 2 are rotated by the rear wheels 3, so that the variable hydraulic motor 13 is driven by the front wheels 2 to perform pumping action. To do. When the variable hydraulic motor 13 acts as a pump, the pressure of the second main circuit 17 becomes high and the pressure of the first main circuit 16 becomes low after the vehicle moves forward, and the second main circuit 1
Since the variable hydraulic pump 15 is driven by the high pressure oil of No. 7 and the rotational resistance of the variable hydraulic pump 15 becomes remarkably large, the rotational load of the engine 7 becomes large. The overall braking force is increased.

Since the braking force acting on the front wheels 2 is determined by the pressure in the second main circuit 17, the pressure for setting the braking force is set in the main controller 23, and the pressure from the second pressure sensor 22 is set. When the pressure exceeds the set pressure, the first solenoid 43 of the solenoid proportional valve 43 of the variable hydraulic pump 15
The variable hydraulic pump 15 is made large in capacity by energizing a and the pressure in the second main circuit 17 is lowered to set pressure. By doing so, the braking force of the front wheels 2 can be maintained at the set braking force, and damage to each part can be prevented.

The above-mentioned braking force of the front wheels 2 is set according to operating conditions, and the setting of the braking force setting pressure will be described below. (1) When the rear wheel 3 is not slipping. 30-when empty
It is set to 150 kg / cm ² . 30-160kg when loaded
/ Cm ² . 100-200kg / c when empty
m ² 125-200 kg / cm ² when the vehicle is downhill
And (2) When the rear wheel 3 is slipping. 50-2 when empty
It is set to 00 kg / cm ² . 50 to 125 kg / when loaded
cm ² 150-200 kg / cm when empty
^Set to ² . 150 to 250 kg / cm ² when the vehicle is downhill. The pressure in the first main circuit 16 is 25 kg / cm ²
And

[0042]

When the abnormal mode is set by the mode changeover switch 32 and the transmission 9 is set to the neutral position, the capacities of the variable hydraulic pump 15 and the variable hydraulic motor 13 are maximized, and the variable hydraulic motor 13 outputs the maximum torque. Therefore, the front wheels 2 can be driven with the maximum driving force. Therefore, the engine 7
When the rear wheel 3 cannot be driven due to an abnormality in the mechanical transmission device that connects the rear wheel 3 and the rear wheel 3, the variable hydraulic motor 13 and the variable hydraulic pump 15
You can run with maximum traction using.

[Brief description of drawings]

FIG. 1 is a side view of a large dump truck.

FIG. 2 is a schematic plan view of a four-wheel traveling device.

FIG. 3 is a hydraulic circuit diagram of a variable hydraulic pump / motor.

FIG. 4 is a flowchart of a traveling operation at the time of abnormality.

FIG. 5 is a flowchart of a traveling operation during normal operation.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Car body, 2 ... Front wheel, 3 ... Rear wheel, 9 ... Transmission, 13 ... Variable hydraulic motor, 15 ... Variable hydraulic pump, 23 ... Main controller, 32 ... Mode changeover switch.

Claims (1)

[Claims] 1. A variable hydraulic motor 13 for connecting the output side of an engine 7 to a rear wheel 3 via a mechanical transmission device including a transmission 9 and driving a front wheel 2 and a variable hydraulic pump driven by the engine 7. In the four-wheel traveling device in which the variable hydraulic pump 15 and the variable hydraulic motor 13 are connected in a circuit, the means for controlling the capacity of the variable hydraulic pump 15 and the means for controlling the capacity of the variable hydraulic motor 13 are provided. Main controller 2 having normal mode and abnormal mode
3 and a mode changeover switch 32, the main controller 23 controls the displacements of the variable hydraulic pump 15 and the variable hydraulic motor 13 in accordance with the rear wheel rotation speed in the normal traveling mode. A control device for a four-wheel drive system in which the main controller 23 maximizes the capacity of the variable hydraulic pump 15 and the variable hydraulic motor 13 when a transmission neutral signal is input.