JPH0658178A - Running control device for inductrial vehicle having radial cylinder variable displacement pump/motor - Google Patents

Abstract

PURPOSE:To prevent accelerating of a vehicle in an opposite direction to a direction corresponding to the position of a forward reverse lever at a time when the running direction of the vehicle is reversed through switching operation of the forward reverse lever. CONSTITUTION:When it is detected by a shift sensor 54 during running of a vehicle that a forward reverse lever 53 is switched, it is discriminated by a controller 61 whether a current change gear ratio exceeds a change gear ratio limit. In which case, when it is decided that the current change gear ratio exceeds the change gear ratio limit, a target throttle opening to a current accelerator opening is calculated from a map where the maximum value of the target throttle opening is set to a high value. A step motor 15 for a valve is driven and controlled such that the opening of the throttle valve is adjusted to the throttle opening. Meanwhile, when the current change gear ratio does not exceeds the change gear ratio limit, the target throttle opening is calculated from a map where the maximum value of the target throttle opening is set to a low value, and a step motor 51 for a valve is driven and controlled.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a traveling control device for an industrial vehicle, and more particularly to a radial cylinder type variable displacement pump /
The present invention relates to a travel control device for an industrial vehicle that travels with a drive wheel rotated by a motor.

[0002]

2. Description of the Related Art In some industrial vehicles such as forklifts and skid steer loaders equipped with a hydraulic device, wheels are driven by hydraulic motors (for example, actual flat blade 1-68).
924). In this type of vehicle, a hydraulic motor is rotated by operating oil supplied from a variable displacement pump that is rotationally driven by an engine, and the amount of oil supplied to the motor, that is, the displacement of the variable displacement pump, is changed to The rotation speed is controlled to control the vehicle speed.

Conventionally, a swash plate type axial piston pump / motor is generally used as the variable displacement pump / motor. However, the swash plate type axial piston pump / motor has the following problems due to the mechanism of converting pressure into torque. That is, in the swash plate type axial piston pump / motor, the piston side pressure is generated at the cylinder front edge and the piston rear end due to the overhang of the piston tip, and the side pressure at the piston rear end opposes the effective output torque. These side pressures become frictional forces, which adversely affect the torque performance during start-up / low speed operation and impair the controllability. However, in the swash plate type motor, the rotational force is transmitted to the output shaft by the piston side pressure.

As a variable displacement pump / motor that solves the problems of the swash plate type axial piston pump / motor, a new radial cylinder type variable displacement pump / motor of FFC (FLUID FORCE COUPLE) system has been proposed (Kita, hydraulic pressure. And Air Pressure, Vol. 20, No. 2 (1989), 7-1
4). This variable displacement pump / motor is basically composed of a cylindrical casing and seven planes which are in contact with the inner surface of the casing by seven static pressure pads provided on the outer periphery and whose inner surface corresponds to the static pressure pads. Coupling ring, a seal bush (piston) perpendicularly contacting each inner surface of the coupling ring, a cylinder block having seven radial cylinders fitted to the seal bush, and a center hole of the cylinder block. It is composed of pintles which are eccentric to the casing center and can be eccentric in the direction perpendicular to the axis. The displacement of the pump or the output of the hydraulic motor changes according to the amount of eccentricity of the pintle.

Conventionally, when a forklift equipped with this FFC type variable displacement pump / motor is switched (switched back) from forward running to reverse running, for example, the forward / backward lever is operated to switch forward. The pintle is controlled so as to be opposite to the eccentric direction of the pintle at, and the traveling direction of the vehicle is changed.

[0006]

However, for example, when an attempt is made to cause the forklift to travel backward by switching the forward / reverse lever position to the reverse traveling position from forward traveling with a high traveling speed (state where the gear ratio is large), Even if the vehicle is made to travel backward by depressing the accelerator pedal greatly, the vehicle may travel forward for a moment without traveling backward. That is, although the forward / reverse lever is switched, the traveling direction of the vehicle may not change and the vehicle may accelerate in the opposite traveling direction.

The reason therefor is that the eccentric speed of the pintle has an upper limit. Therefore, when the gear ratio is large, that is, when the pintle position is largely eccentric from the neutral position, the forward / reverse lever is switched to the reverse drive position. However, the pintle cannot be instantly returned to the neutral position.

That is, even if the forward / reverse lever position is in the reverse drive position, if the pintle is in the eccentric position when the forward drive is in progress, even if the accelerator pedal is depressed to a large extent, the vehicle accelerates without performing reverse drive. To move forward. Therefore, there is a problem that the operability of the forklift is deteriorated.

The present invention has been made to solve the above problems, and its purpose is to respond to the position of the forward / backward lever at that time when the forward / backward lever is switched to reverse the traveling direction of the vehicle. It is an object of the present invention to provide a traveling control device for an industrial vehicle equipped with a radial cylinder type variable displacement pump / motor capable of preventing acceleration of the vehicle in a direction opposite to the direction in which the vehicle is driven.

[0010]

In order to achieve the above object, according to the present invention, a radial cylinder type variable displacement pump / motor driven by an engine to drive driving wheels,
Pintle drive means for changing the gear ratio by changing the eccentricity of the pintle provided in the variable displacement pump / motor, valve drive means for opening and closing the throttle valve, and accelerator opening degree for detecting the opening degree of the accelerator pedal Detection means, pintle position detection means for detecting the amount of eccentricity of the pintle, lever position detection means for detecting the position of the forward / backward lever that is operated when reversing the traveling direction of the vehicle, and throttle valve for the accelerator opening. And a maximum value lower than the maximum value of the target throttle opening stored in the first target throttle opening storage means. Second target throttle opening storage means for storing the target throttle opening of the throttle valve with respect to the accelerator opening, Based on the reference pintle eccentricity amount upper limit value storage means for storing the determined reference pintle eccentricity amount upper limit value, and the pintle eccentricity amount from the pintle position detection means, the pintle eccentricity amount at that time is the reference pintle eccentricity amount upper limit value. A determining means for determining whether or not it exceeds, and when the forward / reverse lever position is switched while the vehicle is traveling,
When the determination means determines that the pintle eccentricity amount at that time exceeds the reference pintle eccentricity amount upper limit value, the target throttle opening amount with respect to the accelerator opening amount at that time is calculated from the first target throttle opening amount storage means. After that, the valve drive means is drive-controlled so as to reach the target throttle opening degree, and when the forward / reverse lever is switched while the vehicle is traveling, the determining means determines that the pintle eccentricity at that time is When it is determined that the reference pintle eccentricity upper limit value is not exceeded, the target throttle opening degree is set after the target throttle opening degree for the accelerator opening at that time is calculated from the second target throttle opening degree storage means. The gist of the present invention is to include valve drive control means for driving and controlling the valve drive means.

[0011]

According to the present invention, when the lever position detecting means detects that the forward / backward lever has been switched while the vehicle is traveling, the determining means determines the pintle eccentricity at that time as the reference pintle eccentricity upper limit value. It is determined whether or not it exceeds. Here, when the determination means determines that the pintle eccentricity amount at that time exceeds the reference pintle eccentricity amount upper limit value, the valve drive control means determines from the first target throttle opening degree storage means at that time. A target throttle opening with respect to the accelerator opening is calculated, and the valve drive means is drive-controlled so as to reach the target throttle opening.

On the other hand, when the discriminating means determines that the pintle eccentricity amount at that time does not exceed the reference pintle eccentricity upper limit value, the valve drive control means
The target throttle opening corresponding to the accelerator opening at that time is calculated from the second target throttle opening storage means, and the valve drive means is drive-controlled to reach the target throttle opening.

That is, the maximum value of the target throttle opening set in the second target throttle opening storage means is
Since it is set lower than the maximum value of the target throttle opening set in the first target throttle opening storage means, the target throttle opening is calculated based on the second target throttle opening storage means. In this case, the engine speed at that time is kept low.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is embodied in a forklift will be described below with reference to the drawings.

As shown in FIG. 1, an output shaft of an engine 1 mounted on a vehicle (not shown) has a drive shaft 3a of a hydraulic pump 3 constituting a radial cylinder type variable displacement pump / motor 2 for traveling. Are drivingly connected. An output shaft 4a of a hydraulic motor 4 that constitutes the variable displacement pump / motor 2 is connected to a drive wheel 7 via a drive shaft 5 and an operating gear mechanism 6. The vehicle travels along with the rotation of the output shaft 4a. Further, the drive shaft 3a is
A hydraulic pump (not shown) for supplying hydraulic oil to a lift cylinder (not shown) for cargo handling work is driven.

In this embodiment, since the hydraulic pump 3 and the hydraulic motor 4 have basically the same structure, the structure of the hydraulic motor 4 will be described as an example. As shown in FIGS. 2 to 4, a couple ring 10 is housed in a housing space surrounded by a cylindrical casing 8 and a rear cover 9 that covers an opening thereof. The couple ring 10 is formed integrally with the output shaft 4a protruding outside the casing 8,
The output shaft 4a is connected to the drive shaft 5 via a coupling (not shown) in the spline 4b.

The couple ring 10 has a bearing 11
It is rotatably supported by the casing 8. Seven shoes (static pressure pads) 12 are attached to the outer circumference of the couple ring 10 at equal intervals so as to rotate integrally with the couple ring 10 (see FIG. 4). Planes 10a are formed on the inner surface of the couple ring 10 at seven locations corresponding to the shoes 12. Further, the couple ring 1 is provided at the center of each plane 10a.
A hole 10b penetrating 0 is formed. Further, a hole 12a penetrating the shoe 12 is formed in the center of the shoe 12.

The rear cover 9 includes a cylinder block 13
The pintle 14 that supports the shaft is movably supported in a direction orthogonal to the axis of the output shaft 4a. As shown in FIGS. 3 and 5, the pintle 14 has a groove 9 a formed in the rear cover 9.
It is composed of a pedestal portion 14a having a trapezoidal prismatic cross section that fits into the pedestal portion, and a truncated conical support portion 14b provided on the pedestal portion 14a so as to project into the couple ring 10. The cylinder block 13 has a fitting hole 13 formed at the center thereof.
By fitting a to the support portion 14b, the pintle 14
Is rotatably supported with respect to.

The pintle 14 has a pair of ports 14c and 14d formed on the peripheral surface of the support portion 14b and a pedestal portion 14a.
A pair of oil passages 15 and 16 which respectively communicate with a pair of ports 14e and 14f formed on the slope are formed to cross each other like a plow. As shown in FIG. 3, one oil passage 15 is connected to the low pressure port 17B formed in the rear cover 9, and the other oil passage 16 is connected to the rear cover 9.
Is connected to the high-pressure port 18B formed in.

Seven cylinder bores 19 are formed in the cylinder block 13 at equal intervals in a direction orthogonal to the peripheral surface of the support portion 14b so as to communicate with the oil passages 15 and 16. In the cylinder bore 19, a piston 20, which is held with its one end in contact with the flat surface 10a, is reciprocally housed. Each of the shoes 12 and the piston 20 is formed so that the maximum pressure receiving area becomes equal. The cylinder block 13 is connected to the couple ring 10 by an Oldham's joint 21 so as to be rotatable integrally therewith.

As shown in FIG. 2, the groove 9 is formed in the pedestal portion 14a.
A servo spool 22 extending along the longitudinal direction of a (the vertical direction in FIG. 2) is attached so as to be movable integrally with the pintle 14. The servo spool 22 is inserted into a hole 23 formed in the pedestal portion 14a with its tip protruding. The servo spool 22 is urged downward in the drawing by a spring 24 interposed between a flange 22a formed at the base end of the servo spool 22 and the end of the hole 23. The stop ring 25 fixed to the tip of the servo spool 22 comes into contact with the outer surface of the pedestal portion 14a, so that the downward movement thereof is restricted. Therefore, the servo spool 22 moves integrally with the pintle 14 until a force larger than the biasing force of the spring 24 acts on the servo spool 22 in the direction opposite to the biasing force.

An accommodating portion 26 is formed in the rear cover 9 at a position corresponding to the groove 9a, and a control rod 27 for driving the pintle 14 via the servo spool 22 is accommodated in the accommodating portion 26. . The control rod 27 penetrates a hole 9b communicating with the groove 9a, and its tip is screwed to the base end of the servo spool 22. In addition, the control rod 27 has a housing portion 2
A guide rod 28 protruding in parallel with the axial direction of the servo spool 22 is inserted into the shaft 6, and the control rod 27 is movable along the guide rod 28.

Further, a step motor 29B is fixed to the rear cover 9 so as to cover the opening of the accommodating portion 26. A male screw 30 is attached to the output shaft 30 of the step motor 29B.
a is formed, and the male screw 30a is attached to the control rod 27.
It is screwed into the screw hole 27 formed in the. Therefore, the control rod 27 moves in the vertical direction of FIG. 2 in accordance with the forward and reverse rotations of the output shaft 30, and the pintle 14 moves along the groove 9 a via the servo spool 22. Then, the servo spool 22, the control rod 27 and the step motor 29B constitute a pintle driving means for driving the pintle 14 in a direction orthogonal to its axis.

The accommodation portion 26 is provided with a pintle position sensor 31B as a pintle position detecting means composed of a potentiometer for detecting the position of the pintle 14. The pintle position sensor 31B is connected to the control rod 27, and the position where the eccentricity δ1 of the pintle 14 is 0, that is, the position where the center of the output shaft 4a and the center of the support portion 14b coincide with each other is used as a reference position (neutral position). It detects how much the pintle 14 has moved from the position.

Now, as described above, the hydraulic pump 3 is
The hydraulic motor 4 has the same mechanical structure.
That is, the pintle 32 on the hydraulic pump 3 side is driven by the step motor 29A in the direction orthogonal to its axis. Further, the position of the pintle 32 is detected by a pintle position sensor 31A as a pintle position detecting means including a potentiometer. Then, the hydraulic pump 3 and the hydraulic motor 4 are provided with a conduit (not shown).
The low-pressure ports 17A and 17B are connected to each other and the high-pressure ports 18A and 18B are connected to each other via (see FIGS. 2 to 5).

Next, the hydraulic pump 3 and the hydraulic motor 4
The operating principle of will be described in detail. First, in the hydraulic motor 4, as shown in FIG. 4, when hydraulic oil is introduced into the cylinder bore 19, the piston 20 pushes the flat surface 10 a toward the outside of the couple ring 10. Each plane 10a at the same time
The hydraulic oil is guided to the outside of the shoe 12 through the hole 10b formed in the center and the hole 12a formed in the shoe 12. This hydraulic oil pushes the couple ring 10 inward. The force of pushing the couple ring 10 from the inside and the outside with hydraulic oil causes the couple ring 10 to receive a couple force by a hydraulic pressure on one side thereof in a size proportional to the eccentric amount of the cylinder bore 19. Then, an output torque proportional to the value obtained by multiplying the pressure of the three cylinder bores 19 communicating with the high pressure port 18B by the sum of the eccentricity amounts is obtained. That is, for example, in the state of FIG. 4, when the upper cylinder bore 19 has a high pressure, the couple ring 10 rotates clockwise in FIG. As a result, the output shaft 4a of the hydraulic motor 4 is rotated.

When the eccentricity δB of the pintle 14 is 0, that is, when the pintle 14 is in the neutral position, the sum of the couples applied to the couple ring 10 becomes zero, so that the output torque is 0. Becomes Therefore, the output shaft 4a of the hydraulic motor 4 is held in a non-rotating state. Further, when the pintle 14 is moved to the upper side from the position shown in FIG. 2 and further moved to the upper side from the position where the eccentricity amount δB becomes 0, the rotation direction of the couple ring 10 becomes the opposite direction to that, and the output The rotation direction of the shaft 4a is also the reverse direction. However, in the apparatus of this embodiment, the eccentricity amount δB of the pintle 14 is changed only on the plus side (see FIG. 6).

Next, in the hydraulic pump 3, the drive shaft 3
When a is driven, the couple ring 10 and the cylinder block 13 are synchronously rotated. Then, the couple ring 10 presses the pistons 20 in the three cylinder bores 19 in communication with the oil passage 16 communicating with the high pressure port 18A corresponding to the eccentricity δA on the plus side of the pintle 32, and the inside of the cylinder bore 19 is pressed. Pressure is applied to the hydraulic oil. Then, the hydraulic oil in the cylinder bore 19 in a state corresponding to the oil passage 16 is supplied to the hydraulic motor 4 via the high pressure port 18A.

On the other hand, when the position of the pintle 32 is moved to the side opposite to that of FIG. 4 with respect to the neutral position (when the eccentricity δA of the pintle 32 is on the negative side), even if the rotation direction of the drive shaft 3a is the same, The couple ring 10 is connected to the low pressure port 17A and is connected to the piston 20 in the three cylinder bores 19.
Press. Therefore, contrary to the above, high-pressure hydraulic oil is supplied to the hydraulic motor 4 from the low-pressure port 17A side. Then, the rotation direction of the hydraulic motor 4 is reversed, and the forklift moves backward.

When the stepper motors 29A and 29B are driven to rotate the output shaft 30, the control rod 27 screwed onto the output shaft 30 is moved along the guide rod 28 in the vertical direction of FIG. When the control rod 27 moves, the pintle 14, via the servo spool 22,
32 moves integrally. The movement direction of the control rod 27 corresponds to the rotation direction of the output shaft 30, and the movement amount is proportional to the rotation amount of the output shaft 30.

In this embodiment, as shown in FIG. 6, the pintle 14 of the hydraulic motor 4 operates in a low speed range during forward travel and during reverse travel (vehicle speed V is -8 to 8 km / h in this embodiment). The eccentricity amount δB is fixed so as to be maximum (7.5 mm). On the other hand, the pintle 32 of the hydraulic pump 3 is
In this region, when the vehicle speed V is zero, the eccentricity amount δ
When A is zero, the amount of eccentricity δA increases in proportion to the vehicle speed V.

In addition, the pintle 14 of the hydraulic motor 4 has a high speed region when moving forward (in this embodiment, the vehicle speed V is 8 to 20 km /
In h), the eccentricity amount δB decreases from the maximum state as the vehicle speed V increases. On the other hand, the pintle 32 of the hydraulic pump 3 is fixed so that the eccentricity amount δA becomes maximum (7.5 mm) in this region.

Therefore, the rotational speed of the couple ring 10 of the hydraulic motor 4 becomes lower than the rotational speed of the couple ring 10 of the hydraulic pump 3 in the low speed region when moving forward and in the reverse direction.
On the contrary, in the high speed region, the rotational speed of the couple ring 10 of the hydraulic motor 4 is higher than that of the couple ring 10 of the hydraulic pump 3. That is, the gear ratio RF between the hydraulic motor 4 and the hydraulic pump 3 (the couple ring 1 of the hydraulic motor 4 is
0 rpm / rotational speed of couple ring 10 of hydraulic pump 3)
Is smaller in the low speed region and larger in the high speed region. Further, the boundary between the low speed region and the high speed region, that is, the vehicle speed V is 8
The gear ratio RF is "1" at km / h.

In this embodiment, in addition to the pintle position detecting sensors 31A and 31B, various sensors described below are provided. That is, as shown in FIG. 1, the accelerator pedal 41 is provided with an accelerator sensor 42 as an accelerator opening detection means for detecting an accelerator opening ACC corresponding to the depression amount, and the brake pedal 43 is provided with a brake depression. A brake sensor 44 that detects the amount is provided. A lift sensor 45 that detects the amount of operation of the lift lever 45 that is operated when the fork (not shown) is moved up and down is provided in the tilt lever 47 that is operated when the fork is tilted back and forth. A tilt sensor 48 for detecting the operation amount is provided.

Further, the feeling adjusting knob 49 operated when adjusting the sensitivity during deceleration of the forklift is provided with a knob sensor 50 for detecting the operation amount. In addition, a throttle valve (not shown) provided in the engine 1 and driven to open and close by the valve step motor 51 is provided with a throttle opening sensor 52 that detects the degree of opening and closing. Each of these sensors 42,
44, 46, 48, 50 and 52 are all composed of potentiometers.

Further, the forward / backward lever 53, which is operated when switching the forward or reverse of the forklift, is provided with a shift sensor 54 composed of a limit switch for detecting its shift position (forward / neutral / reverse). There is.
Further, the engine 1 is provided with an engine rotation speed sensor 55 including a pickup coil for detecting the rotation speed thereof. A vehicle speed sensor 56 is provided between the gear mechanism 6 and the output shaft 4a to detect the rotation speed of the drive shaft 5 to detect the vehicle speed V of the forklift.

Further, in this embodiment, a controller 61 for driving and controlling the step motors 29A, 29B and the valve step motor 51 is provided.
The controller 61 includes the sensors 31A, 31
B, 42, 44, 46, 48, 50, 52, 54, 5
Detection signals from 5, 56 are input.

The controller 61 includes a CPU (central processing unit) 62, a read-only program memory (ROM) 63 that stores each control program, and a readable and rewritable work memory (RAM) that stores calculation processing results and the like. ) 64, an input / output interface 65, etc.

The CPU 62 includes an accelerator sensor 42, a brake sensor 44, a lift sensor 46, a tilt sensor 48, a knob sensor 50, a throttle opening sensor 52, a hydraulic pump via the A / D converters 66 to 73 and the input / output interface 65. The pintle position sensor 31A on the side 3 and the pintle position sensor 31B on the side of the hydraulic motor 4 are connected to each other. Further, the shift sensor 54 is connected to the CPU 62 via an input / output interface 65. Further, the CPU 62 is provided with F / V converters 74, 7
5, the engine speed sensor 55 and the vehicle speed sensor 56 are connected via the A / D converters 76 and 77 and the input / output interface 65.

The CPU 62 uses the sensors 31A, 31
B, 42, 44, 46, 48, 50, 52, 54, 5
Based on the detection signals from 5, 56, the accelerator opening ACC and the brake depression amount at that time, or the eccentricity amounts δA, δB from the neutral positions of the pintles 32, 14 on the hydraulic pump 3 side and the hydraulic motor 4 side are detected. It is supposed to do.

Step motors 29A and 29B on the hydraulic pump 3 side and the hydraulic motor 4 side are connected to the CPU 62 via an input / output interface 65 and drive circuits 78 and 79. Further, the valve step motor 51 is connected to the CPU 62 via the input / output interface 65 and the drive circuit 80. And the CPU 62
Are the sensors 31A, 31B, 42, 44, 46,
Based on the detection results from 48, 50, 52, 54, 55, 56, the step motors 29A, 29B and the valve step motor 51 are preferably controlled.

In this embodiment, R of the controller 61
The OM 63 stores a map A preset for performing various controls, and the CPU 62 uses the map A.
The step motors 29A, 29B and the valve step motor 51 are drive-controlled based on the above.

The map A shown in FIG. 7 is stored in the ROM 63.
Is remembered. This map A shows the accelerator opening ACC
The target throttle opening SLO1 is set in advance. Further, when the map A is described in detail, the target throttle opening SLO1 is set to increase with the magnitude of the accelerator opening ACC while the accelerator opening ACC is "0 to X1". When the accelerator opening ACC is "X1" or more, the target throttle opening SLO1 is set to be maximum.

A map B shown in FIG. 8 is stored in the ROM 63. In this map B, the target throttle opening SLO1 with respect to the accelerator opening ACC is preset. Furthermore, when describing this map B in detail,
While the accelerator opening ACC is "0 to X2", the target throttle opening SLO2 for the accelerator opening ACC is set at the same rate of increase as in the map A. When the accelerator opening ACC is "X2" or more, the target throttle opening SLO2 is set to be maximum (16step). The throttle opening SLO is "1.
The engine speed ENG at "6 steps" is set to be slightly higher than the engine speed ENG during idling.

That is, the value of the maximum target throttle opening SLO2 of the map B is set to be significantly lower than the maximum target throttle opening SLO1 of the map A.
Each of these maps A and B is used by the controller 61 depending on the traveling condition at that time.

The ROM 63 also stores a gear ratio limit RF1 as an upper limit value of the reference pintle eccentricity amount. The gear ratio limit RF1 is a gear ratio that serves as a reference value when the forklift is reversed from forward (reverse) traveling to reverse (forward) traveling.

In this embodiment, as shown in FIG.
The gear ratio limit RF1 is set to "0.2" during the reverse traveling of the forklift from the forward traveling to the reverse traveling, and the gear ratio limit RF1 is set during the reverse traveling of the forklift traveling from the backward traveling to the forward traveling. "-
It is set to be "0.2". The controller 61 selectively uses the maps A and B based on the gear ratio limit RF1.

First and second by the controller 61
The target throttle opening storage means, the reference pintle eccentricity amount upper limit storage means, the determination means, and the valve drive control means.

Next, the operation of this embodiment will be described with reference to the flowchart. FIG. 10 is a flow chart showing a processing routine executed by the controller 61 in the present embodiment, which is executed by a regular interruption every predetermined time.

When the processing shifts to this routine, first, at step 101, the shift position of the forward / backward lever 53 at that time is read based on the detection signal from the shift sensor 54. Next, at step 102, the accelerator opening ACC at that time is read based on the detection signal from the accelerator sensor 42. In the next step 103, the throttle opening SLO at that time is read based on the detection signal from the throttle opening sensor 52.
In step 104, the pintle position sensor 31
Based on the detection signals from A and 31B, both pintles 3
The eccentricity amounts δA and δB of 2 and 14, that is, the gear ratio RF is read.

In step 105, it is determined whether the shift position read in step 101 is forward or backward. Then, when the shift position is neither forward or backward, that is, in the neutral position, the subsequent processing is temporarily terminated. If the shift position is forward or backward, the process proceeds to the next step 106. Step 106
In Fig. 7, the target throttle opening SLO1 for the accelerator opening ACC at that time is calculated based on the map A in Fig. 7. In the following step 107, it is determined whether or not the shift position read in step 101 has been switched.

That is, it is determined whether or not the forward / reverse lever 53 is switched from the forward drive position to the reverse drive position or from the reverse drive position to the forward drive position. Here, if the forward / backward lever 53 is not switched, that is, if the traveling direction of the vehicle is not reversed, the process proceeds to step 108.

In step 108, the valve step motor 51 is drive-controlled so that the throttle opening SLO becomes the target throttle opening SLO1 calculated in step 106, and the subsequent processing is temporarily terminated.

On the other hand, in step 107, when it is determined that the forward / reverse lever 53 is switched and the traveling direction of the vehicle is reversed, the process proceeds to step 109. In step 109, it is determined whether the gear ratio RF read in step 104 exceeds the gear ratio limit RF1. Here, the gear ratio RF is the gear ratio limit R
When it is determined that the value exceeds F1, the above step 108 is performed.
After jumping to and performing the processing there, this processing routine is once ended.

On the other hand, in step 109, the gear ratio R
If F does not exceed the gear ratio limit RF1, the process proceeds to step 110. In step 110,
The target throttle opening degree SLO2 for the accelerator opening degree ACC at that time is calculated from the map B, and the routine proceeds to step 111. Then, in step 111, the valve step motor 51 is drive-controlled so that the throttle opening SLO becomes the target throttle opening SLO2 calculated in step 110.

Then, in the next step 112, it is determined again whether the gear ratio RF exceeds the gear ratio limit RF1. Here, the gear ratio RF is still the gear ratio limit R.
If it is determined that F1 is not exceeded, the valve step motor 51 is continuously driven and controlled so that the throttle opening SLO becomes the target throttle opening SLO2.

On the other hand, the gear ratio RF is the gear ratio limit RF1.
When it is determined that the value exceeds, the process jumps to step 108. That is, the valve stepping motor 51 is driven and controlled so that the target throttle opening degree SLO1 with respect to the throttle opening degree ACC at that time is obtained, and the subsequent processing is temporarily terminated.

As described above, by performing the above processing, for example, when the forward / reverse switching lever 53 is switched to the reverse traveling position during forward traveling of the forklift, the gear ratio RF at that time is set to the gear ratio limit RF1. It is determined whether or not it exceeds.

At this time, the gear ratio RF does not exceed the gear ratio limit RF1 ("0.2") (the gear ratio R
If F is “0.2” or more), the map B calculates the target throttle opening SLO2 with respect to the accelerator opening at that time. Then, after that, the valve step motor 51 is drive-controlled so that the throttle opening SLO becomes the target throttle opening SLO2.

That is, the gear ratio RF when the forward / reverse lever 53 is switched to the reverse traveling position is the gear ratio limit RF.
When the value is higher than "0.2" of 1, the accelerator opening AC
No matter how large C is, the target throttle opening RF2 does not exceed "16step". That is, the engine speed ENG at that time is kept low.

As a result, the gear ratio RF at that time is, for example, the gear ratio RF "1.5" during forward travel, and the accelerator opening degree ACC is high, even though the forward / backward lever 53 is in the reverse travel position. Even in this case, the engine speed ENG is kept low, so that the forklift does not travel forward.

The gear ratio RF is the gear ratio limit RF.
When the value exceeds "0.2", which is 1 (in this case, "0.2")
Target point opening SLO1 with respect to the accelerator opening ACC at that time based on map A)
Is calculated. That is, the target throttle opening (target throttle opening SLO1) is changed from map A instead of map B.
Is calculated.

That is, when the accelerator opening ACC exceeds X2 and the gear ratio RF becomes higher than the gear ratio limit RF1 of "0.2" and becomes smaller than "0.2". , The throttle opening SLO is immediately set to "16
It becomes bigger than "step". That is, the engine speed ENG is immediately increased.

Therefore, when the gear ratio RF becomes smaller than "0", the engine speed ENG is maintained at a high speed, so that the forklift quickly moves backward. On the other hand, when the forklift is moved from the backward drive to the forward drive, the gear ratio limit RF1 is "-0.2". Therefore, when the gear ratio RF does not exceed the gear ratio limit RF1 of "-0.2" (when the gear ratio RF is larger than "-0.2") during the switching operation of the forward / reverse switching lever 53. , The target throttle opening SLO2 with respect to the accelerator opening at that time is calculated by the map B. After that, the valve step motor 51 is drive-controlled so that the throttle opening SLO becomes the target throttle opening SLO2.

That is, if the gear ratio RF at that time is smaller than "-0.2" even though the forward / backward lever 53 is switched to move the forklift forward, the accelerator opening ACC No matter how large, the target throttle opening RF2 does not exceed "16step". That is, the engine speed ENG at that time is kept low.

As a result, when the forklift is moved from the backward drive to the forward drive, the engine speed ENG is low even when the gear ratio RF is the gear ratio RF during the reverse drive and the accelerator opening ACC is large. , Forklifts cannot run backwards.

The gear ratio RF is the gear ratio limit RF.
When the value exceeds "-0.2" which is 1, the target throttle opening SLO1 with respect to the accelerator opening ACC at that time is calculated from the map A, and the engine speed ENG is immediately increased.

Therefore, after the forward / reverse lever 53 is switched, the forklift quickly moves forward. As described above, in the present embodiment, when the forklift is reversed from forward (reverse) traveling to reverse (forward) traveling, the gear ratio RF exceeds the gear ratio limit RF1 even if the accelerator opening ACC at that time is large. If not, the engine speed ENG is controlled to be low. Therefore, unlike the conventional case, after the forward / reverse lever 53 is switched from the forward traveling position (reverse traveling position) to the reverse traveling position (forward traveling position), the forklift travels in the direction opposite to the traveling direction on the side of the switching operation. Will disappear. As a result, the operability of the forklift can be significantly improved.

The present invention is not limited to the above embodiments, but may be configured as follows, for example, without departing from the spirit of the invention. (1) In the above embodiment, the pintles 32 and 14 of the hydraulic pump 3 and the hydraulic motor 4 are separately provided in the step motors 29A and 2A.
Although it is driven by 9B, the pintles 32, 14 may be driven by one step motor by a link mechanism (not shown).

(2) In the above embodiment, the gear ratio limit RF1 as the reference gear ratio upper limit value is "-0.2" and "0.
However, this numerical value may be changed as appropriate. (3) In the above embodiment, the maximum target throttle opening SLO2 on the map B is set to "16step", but this numerical value may be changed appropriately.

(4) In the above embodiment, the pintle position sensors 31A and 31B are constituted by potentiometers. Instead of this, rotary encoders for detecting the rotation amounts of the step motors 29A and 29B are used to output from the reference position. A configuration may be adopted in which the eccentricity amounts δA and δB are calculated based on the rotation amount of the shaft 30.

[0072]

As described in detail above, according to the present invention,
To prevent accelerating the vehicle in the direction opposite to the direction corresponding to the position of the forward / backward lever at that time when switching the forward / backward lever to reverse the traveling direction of the vehicle, to improve the operability of the vehicle. It has an excellent effect that

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment embodying the present invention.

FIG. 2 is a cross-sectional view of the hydraulic motor taken along the moving direction of the pintle.

FIG. 3 is a cross-sectional view of the hydraulic motor taken along a plane orthogonal to the moving direction of the pintle.

FIG. 4 is a cross-sectional view of a state in which the hydraulic pump or the hydraulic motor is cut along a plane intersecting the output shaft.

FIG. 5 is a schematic perspective view of a pintle.

FIG. 6 is a diagram showing a relationship between an eccentric amount of a pintle of a hydraulic pump and a hydraulic motor and a vehicle speed.

FIG. 7 is a map in which a target throttle opening is set with respect to an accelerator opening.

FIG. 8 is a map in which a target throttle opening is set with respect to an accelerator opening.

FIG. 9 is a schematic graph showing a gear ratio limit.

FIG. 10 is a flowchart showing a treatment routine executed by a controller.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Engine, 2 ... Variable displacement pump / motor, 7 ... Drive wheel, 14, 32 ... Pintle, 22 ... Servo spool which comprises pintle drive means, 27 ... Control rod which comprises pintle drive means, 29A, 29B ... Pintle Step motor constituting drive means 41 ... Accelerator pedal, 42 ... Accelerator sensor as accelerator opening detection means, 51 ... Valve step motor as valve drive means, 53 ... Forward / reverse lever, 54 ... As lever position detection means Shift sensor, 61 ... First and second target throttle opening storage means, reference pintle eccentricity upper limit storage means, discriminating means, controller as valve drive control means, RF ... gear ratio, RF1 ... reference pintle eccentricity Reference gear ratio range as range, SLO ... throttle opening, S
LO1, SLO2 ... Target throttle opening, .delta.A, .delta.B ...
Eccentricity.

Continuation of front page (51) Int.Cl. ⁵ Identification code Office reference number FI Technical display location F02D 29/00 H 9248-3G 41/04 310 G 8011-3G 45/00 314 M 7536-3G F03C 1/253 6907-3H 1/40 6907-3H F04B 1/04 8311-3H 1/26 102 8311-3H

Claims (1)

[Claims] 1. A radial cylinder type variable displacement pump / motor driven by an engine to drive driving wheels, and a pintle for changing a gear ratio by changing an eccentric amount of a pintle provided in the variable displacement pump / motor. Driving means, valve driving means for opening and closing the throttle valve, accelerator opening detecting means for detecting the opening of the accelerator pedal, pintle position detecting means for detecting the amount of eccentricity of the pintle, and reversing the traveling direction of the vehicle Lever position detecting means for detecting the position of the forward / backward lever that is operated at the time, first target throttle opening storage means for storing in advance the target throttle opening of the throttle valve with respect to the accelerator opening, and the first If the maximum throttle opening value stored in the target throttle opening storage means is lower than the maximum value Second target throttle opening degree storage means for storing a target throttle opening degree of the throttle valve with respect to the throttle opening degree, reference pintle eccentricity amount upper limit value storage means for storing a preset reference pintle eccentricity amount upper limit value, and the pintle. Based on the pintle eccentricity from the position detecting means, a determining means for determining whether or not the pintle eccentricity at that time exceeds the reference pintle eccentricity upper limit value, and a forward / backward lever position switching operation while the vehicle is traveling. When the determination means determines that the pintle eccentricity amount at that time exceeds the reference pintle eccentricity amount upper limit value,
After calculating the target throttle opening for the accelerator opening at that time from the first target throttle opening storage means,
The valve drive means is driven and controlled so that the target throttle opening degree is achieved. On the other hand, when the forward / reverse lever is switched while the vehicle is traveling, the determination means determines the pintle eccentricity at that time as the reference pintle. When it is determined that the eccentricity amount upper limit value is not exceeded, the target throttle opening degree with respect to the accelerator opening at that time is calculated from the second target throttle opening degree storage means, and then the valve is driven to reach the target throttle opening degree. A traveling control device for an industrial vehicle, comprising a radial cylinder type variable displacement pump / motor comprising a valve drive control means for driving and controlling the means.