JPH0658409A - Running control device for industrial vehicle provided with radial cylinder variable capacity pump/motor - Google Patents

Abstract

PURPOSE:To make smooth inching running of an industrial vehicle provided with a radial cylinder variable capacity pump/motor. CONSTITUTION:A driving shaft 3a of a hydraulic pump 3 for running is drivingly connected to an output shaft of an engine 1. An output shaft 4a of a hydraulic motor 4 is connected to a driving wheel 7 through a driving shaft 5 and an operation gear mechanism 6. When an braking pedal 43 is operated during running, a controller 61 drives pintles 14, 32 so as to decrease a transmission ratio RF. A load in respect to the engine 1 is thus decreased, and a target engine speed in respect to every vehicle speed is highered compared to the case that the braking pedal 43 is not operated. As a result, the engine speed required for running is secured, while the engine speed required for cargo work is secured, and inching running is enabled.

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 plane inside the couple ring, a cylinder block having seven radial cylinders that fit with 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. It is considered that the FFC type variable displacement pump / motor is used in an industrial vehicle instead of the swash plate type axial piston pump / motor.

[0005]

However, the above-mentioned FFC
A so-called dynamic brake has been adopted as a braking means for a vehicle equipped with a system variable displacement pump / motor. That is, by setting the accelerator pedal depression amount to zero, the eccentric amount of the pintle becomes zero, the rotation of the variable displacement pump / motor is stopped, and the vehicle is stopped. Therefore, no brake pedal is provided in this type of industrial vehicle.

Therefore, there is no way to carry out so-called inching traveling, which is carried out by a general swash plate type forklift, in which the cargo handling work is performed while traveling at a low speed by depressing both the accelerator pedal and the brake pedal.

The present invention has been made in view of the above problems, and an object thereof is to perform inching traveling capable of smoothly performing inching traveling in an industrial vehicle equipped with a radial cylinder type variable displacement pump / motor. It is to provide a control device.

[0008]

To achieve the above object, in the present invention, a radial cylinder type variable displacement pump / motor which is driven by an engine and drives driving wheels, and the variable displacement pump / motor are provided. Pintle drive means for changing the eccentricity of the pintle that is displaced to control the gear ratio of the vehicle, and accelerator opening detection means for detecting the operation amount of the accelerator pedal operated to control the opening of the throttle valve. A valve driving means for opening and closing the throttle valve; a target opening calculating means for calculating a target opening of the throttle valve based on a detection result of the accelerator opening detecting means; and a target opening calculating means Valve drive control means for driving and controlling the valve drive means based on the target opening degree, and the target opening degree calculated by the target opening degree calculating means. In a travel control device for an industrial vehicle equipped with a radial cylinder type variable displacement pump / motor having a pintle drive control means for drivingly controlling the pintle drive means based on the above, a brake pedal and an operation amount of the brake pedal are detected. The brake operation amount detecting means, and the pintle driving means so that the gear ratio at that time is smaller than that when the brake pedal is not operated, according to the operation amount of the brake pedal based on the brake operation amount detecting means. The gist of the present invention is to provide a second pintle drive control means for drive control.

[0009]

According to the above construction, the operation amount of the accelerator pedal is detected by the accelerator opening detecting means. The target opening calculation means calculates the target opening of the throttle valve based on the detection result of the accelerator opening detection means. Then, based on the target opening calculated by the target opening calculation means,
The valve drive control means drives and controls the valve drive means to open and close the throttle valve. As a result, the engine speed is changed.

Further, the pintle drive control means drives and controls the pintle drive means based on the target opening degree calculated by the target opening degree calculation means. Therefore, the variable displacement pump /
The eccentric amount of the pintle provided on the motor is changed, and the displacement of the pintle controls the gear ratio of the vehicle. The rotation of the engine is transmitted to the drive wheels via the radial cylinder type variable displacement pump / motor according to the gear ratio.

On the other hand, the operation amount of the brake pedal is detected by the brake operation amount detecting means. Then, according to the operation amount of the brake pedal based on the detection means, the second pintle drive control means drives and controls the pintle drive means so that the gear ratio at that time becomes smaller than that when the brake pedal is not operated. It Therefore, the gear ratio decreases with the operation of the brake pedal, and the load on the engine decreases. Therefore, by operating the brake pedal, the engine speed increases more than when the brake pedal is not operated, and with the increase, the driving force necessary for traveling and cargo handling work is secured. .

[0012]

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.

A housing 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 housed in the housing 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.
Is screwed into the screw hole 27a formed in the. Therefore,
With the forward and reverse rotation of the output shaft 30, the control rod 27
2 moves in the vertical direction in FIG. 2, and the pintle 14 moves along the groove 9a 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.

A pintle position sensor 31 composed of a potentiometer for detecting the position of the pintle 14 is provided in the accommodating portion 26.
B is provided. The pintle position sensor 31B is connected to the control rod 27, and the position where the eccentricity amount δ1 of the pintle 14 is 0, that is, the center of the output shaft 4a and the support portion 1 are arranged.
The position at which the center of 4b coincides with the reference position (neutral position) is used to detect how much the pintle 14 has moved from the neutral 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 composed of a potentiometer. Then, the hydraulic pump 3 and the hydraulic motor 4 are connected to each other via a pipe line (not shown) to form the low-pressure port 17 of each other.
A and 17B are connected to each other and high pressure ports 18A and 18B are connected to each other (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 can obtain a rotational force corresponding to the sum of the couples, and the couple ring 10 has the same rotational force. Rotate clockwise. 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 step 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 the low speed range during forward travel and in the 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 during forward travel and during the reverse travel.
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 is provided as a brake operation amount detecting means for detecting the amount BRK. Also,
A lift sensor 45, which detects the amount of operation of the lift lever 45 that is operated when moving up and down a fork (not shown), is provided in the tilt lever 47 that is operated when tilting the fork back and forth. A tilt sensor 48 for detecting the operation amount is provided.

Further, the feeling adjusting knob 49, which is operated when adjusting the sensitivity during deceleration of the forklift, is provided with a knob sensor 50 for detecting the operation amount (SOFT to HARD). 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. These sensors 42, 44, 46, 48, 50, 5
2 is composed of all potentiometers.

Further, the forward / reverse 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 constitutes pintle drive control means, target opening calculation means, valve drive control means, and second pintle drive control means.

The controller 61 includes a CPU (central processing unit) 62, a read-only program memory (ROM) 63 storing each control program, and a readable / rewritable work memory (operation result, etc.). A RAM) 64, an input / output interface 65, etc. are provided.

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 degree ACC, the brake depression amount BRK, or the eccentric amounts δA, δB from the neutral positions of the pintles 32, 14 on the hydraulic pump 3 side and the hydraulic motor 4 side, etc. It is designed to detect.

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 various maps A to I set in advance for performing various controls, and the CPU 62 uses the step motors 29A and 29A based on these maps A to I.
29B and the valve step motor 51 are drive-controlled.

That is, the ROM 63 stores a map A shown in FIG. 7 in which the target throttle opening SLO1 with respect to the accelerator opening ACC at that time is preset. Further, the ROM 63 stores the engine speed EN for each throttle opening SLO obtained by the experiment shown in FIG.
Based on the relationship of the shaft output ST with respect to G (hereinafter, referred to as map B for convenience of description), the target engine speed E with respect to the accelerator opening ACC at each time shown in FIG.
A map C in which NG1 is set is stored. In this map C, an engine speed ENG capable of obtaining the maximum shaft output STMAX at the accelerator opening ACC at that time based on the maps A and B is set as a target engine speed ENG1 at that time. .

Further, in the ROM 63, PI at the time of feedback control for the speed ratio RF shown in FIG.
Gain [feedback coefficient KFB (KP is a differential coefficient,
KI is an integration coefficient)] and a map D in which a preset value is stored.

That is, as shown in FIG. 17, the controller 61 calculates the target throttle opening SLO1 with respect to the accelerator opening ACC at that time based on the map A. Then, the valve step motor 51 is drive-controlled so that the throttle opening SLO becomes the target throttle opening SLO1, and the engine speed ENG is controlled.

Further, in the ROM 63, as shown in FIG. 11, the division is set based on the throttle opening SLO (corresponding to the accelerator opening ACC) and the gear ratio RF (corresponding to the eccentricity amounts δA and δB). Step motor 29A,
A map E indicating the control area of 29B is stored. In this map E, the control area is two area boundary lines,
Is divided into three regions, that is, a first feedforward control region X, a feedback control region Y, and a second feedforward control region Z.

Here, the above-mentioned area boundary line will be described. First, in map E, throttle opening SL
A point where O is zero and the gear ratio RF is zero is set as a point O. Further, the point where the throttle opening SLO is "64step" and the gear ratio RF is "0.6" is point A, and the throttle opening SL
O is "108 step (maximum)" and the gear ratio RF is "0.
The point "6" is designated as point B. The area boundary lines are points O and A.
And a line connecting point B.

Further, the throttle opening SLO is "40st
The point where the gear ratio RF is "1" at "ep" is point C, the throttle opening SLO is "72step" and the gear ratio RF is "2.
The point "5 (maximum)" is designated as point D. Further, the throttle opening SLO is “108 step” and the gear ratio RF is “2.
The point "5" is designated as point E. The area boundary line is a line connecting points O, C, D and E.

The range of the first feedforward control area X is a portion sandwiched by the horizontal axis (throttle opening SLO) of the map E and the area boundary line. Further, the range of the feedback control area Y is a portion sandwiched between the area boundary line and the area boundary line. Further, the range of the second feedforward control area Z is a portion sandwiched by the area boundary line and the vertical axis (gear ratio RF) of the map E.

Therefore, for example, it is assumed that the forklift is started by depressing the accelerator pedal 41 while the forklift is stopped, that is, when the gear ratio RF is zero. When the throttle opening SLO at this time is "60step", the gear ratio RF is zero, and therefore the controller 61 recognizes that the current region is within the first feedforward control region X. Then, the controller 61 feed-forward-controls the step motors 29A and 29B based on the map F shown in FIG. In this map F, the target gear ratio RF1 for the throttle opening SLO at that time is preset. As shown in the figure, when the throttle opening SLO is between "0 and 64 step", the target gear ratio RF1 increases with the increase of the throttle opening SLO. In addition, the throttle opening SLO
Is larger than "64step", the target gear ratio RF1 is set to a constant "0.6" regardless of the throttle opening SLO. That is, the throttle opening SLO and the target gear ratio R in this map F
The relationship with F1 corresponds to the area boundary line in the map E of FIG. 11 (see FIGS. 11 and 12).

Further, for example, the throttle opening SLO is "7".
If the gear ratio RF is "1" in "2step", the controller 61 recognizes that the current region is within the feedback control region Y based on the map E. Then, the controller 61 determines the accelerator opening ACC (throttle opening SLO) at that time based on the map C shown in FIG.
The target engine speed ENG1 for is calculated. After that, the engine speed ENG is equal to the target engine speed ENG.
The stepper motors 29A and 29B are feedback-controlled so as to be equal to 1. That is, at this time, the step motors 29A and 29A based on the map D of FIG.
B is driven and controlled, and the eccentricity amounts δA of the pintles 32 and 14 are
δB is controlled. Therefore, the gear ratio RF is changed, and the load on the engine 1 is appropriately changed. As a result, the maximum shaft output STMAX at the accelerator opening ACC at that time is obtained.

Further, for example, when the throttle opening SLO is "40step" and the gear ratio RF is "2",
The controller 61 determines that the current area is second based on the map E.
Recognize that it is within the feedforward control area Z. Then, the controller 61 feed-forward-controls the step motors 29A and 29B based on the map G shown in FIG. This map G shows the target gear ratio RF2 for the throttle opening SLO at that time.
Is set in advance. As shown in the figure, when the throttle opening SLO is between "0-40step", the target gear ratio RF2 increases as the throttle opening SLO increases, and the throttle opening SLO becomes "40step".
When "p", the target gear ratio RF2 becomes "1". Further, when the throttle opening SLO is between "40 to 72 step", the target gear ratio RF2 is equal to the throttle opening SL.
It further increases as O increases, and the throttle opening SLO
When is “72 step”, the target gear ratio RF2 is “2.5 (maximum)”. Furthermore, the throttle opening S
When LO becomes larger than "72step",
The target gear ratio RF1 is set to be constant "2.5" regardless of the throttle opening SLO. That is,
The relationship between the throttle opening SLO and the target gear ratio RF1 on the map G corresponds to the area boundary line on the map E in FIG. 11 (see FIGS. 11 and 13).

Further, the ROM 63 stores a map H shown in FIG. 14 in which a coefficient Kα for multiplying the target gear ratio RF2 of FIG. 13 with respect to the brake depression amount BRK is set in advance. According to this map H, when the brake depression amount BRK is less than 70%, the coefficient Kα applied to the target gear ratio RF2 decreases as the depression amount BRK increases.

Therefore, as shown in FIG. 15, when the brake pedal is depressed, the target gear ratio RF2 of the map G described above is obtained.
Is multiplied by the coefficient Kα determined based on the map H. Therefore, when the brake depression amount BRK is less than 70%, the controller 61 sets the target gear ratio R
Feedforward control is performed so that F2 becomes small (from the dotted line to the solid line in FIG. 15). Therefore, the vehicle speed V at that time
The target engine speed ENG1 with respect to is higher than that when the brake pedal 43 is not depressed.

When the brake depression amount BRK is 70% or more, the controller 61 controls to quickly return the eccentric amount of the pintle 32 to zero. That is, the vehicle speed V is controlled so as to quickly become zero. However, when the accelerator pedal 41 is depressed, the engine speed ENG is held according to the accelerator opening degree ACC.

In the ROM 63, the operation position (SOFT to HAR) of the feeling adjusting knob 49 shown in FIG.
A map I in which the rotational speeds SMA and SMB of the step motors 29A and 29B for D) are preset is stored.

As shown in FIG. 17, the controller 61 changes the rotational speeds SMA and SMB of the step motors 29A and 29B at the time of deceleration according to the knob operating position at that time. That is, when the operation position of the feeling adjusting knob 49 is in SOFT, the rotation speeds SMA and SMB of the step motors 29A and 29B are the lowest (for example, 1steps / 16 ms), and when the operation position is in HARD, the step motor 29A,
The rotation speed SMA, SMB of 29B is the highest (eg 10s
(Teps / 16 ms).

When the brake depression amount BRK is equal to or greater than the predetermined amount (70%), the controller 61 controls the feeling adjusting knob 4 as described above.
9 regardless of the operating position of the step motors 29A, 29
The vehicle speed V is always controlled to be the maximum speed so that the vehicle speed V becomes zero.

Next, the operation of this embodiment will be described. In the present embodiment, as described above, in addition to the engine speed control which is the main control, the region control (including the maximum shaft output control), the inching control and the deceleration feeling control are performed for each condition. Each of these controls will be described in detail below based on various flowcharts.

First, engine speed control (main control)
Will be described. FIG. 18 is a flow chart showing a main control processing routine executed by the controller 61 in the present embodiment, which is executed by a timed interrupt every predetermined time.

When the processing shifts to this routine, first, at step 101, the accelerator opening degree ACC at that time is read based on the detection signal from the accelerator sensor 42.

In the following step 102, the target throttle opening SLO1 for the accelerator opening ACC is calculated based on the map A in FIG. Then, in step 103, the valve step motor 51 is drive-controlled so that the current throttle opening SLO becomes the target throttle opening SLO1. Along with this, the throttle valve is opened / closed, and the engine 1 is drive-controlled based on the opening thereof. Then, the controller 61 once ends the subsequent processing.

The controller 61 performs the above-mentioned main control processing as well as area control for each condition. 19 and 20 (a), (b), and (c) are flowcharts showing the processing routine of the region control for each condition executed by the controller 61 in the present embodiment, which is executed by the regular interruption at every predetermined time. To be done.

When the processing shifts to this routine, first, at step 201, the throttle opening SLO corresponding to the accelerator opening ACC at that time is read based on the detection signal from the accelerator sensor 42 or the like.

In step 202, the eccentricity amounts δA and δB of both pintles 32 and 14 are read based on the detection signals from the pintle position sensors 31A and 31B. Next, in the throttle 203, the accelerator opening A
Throttle opening SLO and eccentricity δA corresponding to CC,
The gear ratio RF corresponding to δB is calculated, and which control region (X, Y, Z) the present belongs to is determined based on the throttle opening SLO and the gear ratio RF. Here, which region the current control region belongs to is determined based on the map E shown in FIG. 11 described above.

If the control area at that time is the first feedforward area X, the processing is performed as shown in FIG.
The routine proceeds to the first feedforward region control routine shown in (a).

When the process shifts to this feedforward region control, first, in step 301, the process shown in FIG.
The throttle opening SLO at that time based on the map F of FIG.
The target gear ratio RF1 for is calculated.

Next, at step 302, it is judged if the throttle opening SLO at that time is less than "64step". If the throttle opening SLO is less than “64step”, the process proceeds to step 303.

In step 303, the actual gear ratio R
The step motor 29A is driven and controlled at the lowest speed so that F becomes the target gear ratio RF1 calculated in step 301, the pintle 32 is eccentric, and the subsequent processing is once ended.

If the throttle opening SLO is "64step" or more in step 302, the process proceeds to step 304. In step 304, the gear ratio RF is the target gear ratio RF calculated in step 301.
The step motor 29A is driven and controlled at the maximum speed so as to be 1, and the pintle 32 is eccentric, and the subsequent processing is once ended.

As described above, by performing the above-mentioned first feedforward control, first, when the forklift starts, the throttle opening SLO becomes "64step".
If less, that is, if the speed increase rate requested by the driver is relatively small, the step motor 29A is drive-controlled at the minimum speed. Therefore, when starting the low speed traveling, the gear ratio RF slowly increases, so that a smooth start is possible and a good fine operability can be experienced.

Further, the throttle opening SLO is "64st
When it is equal to or more than “ep”, that is, when the acceleration rate requested by the driver is relatively large, the step motor 29A is drive-controlled at high speed. Therefore, in this case, the gear ratio RF is rapidly increased, and the vehicle can be started quickly. Furthermore, in this area, since feedforward control is performed,
With the depression of the accelerator pedal 41, the vehicle can be started immediately without being delayed, and the response performance can be improved.

If it is determined in step 207 of the region control for each condition of FIG. 19 that the feedback region control is performed, the process proceeds to the feedback region control routine of FIG. 20 (b).

When the processing shifts to this feedback region control, first, at step 401, the target engine speed ENG1 for the accelerator opening ACC read at step 202 is calculated based on the map C. Here, the calculated target engine speed ENG1
Is the rotational speed at which the maximum shaft output STMAX at the accelerator opening ACC (throttle opening SLO) at that time can be obtained.

In the following step 402, the read actual engine speed ENG is equal to the target engine speed EN.
The step motors 29A and 29B are feedback-controlled so as to attain G1. That is, at this time, the step motors 29A and 29B are drive-controlled while referring to the map D. Then, the subsequent processing is temporarily terminated.

In this way, the step motors 29A, 29
By controlling B to be driven, the eccentric amounts δA and δB of the pintles 32 and 14 are appropriately controlled. Therefore, the gear ratio RF is changed, and the load applied to the engine 1 is appropriately changed. Therefore, the engine speed ENG controlled in the main control is changed to the target engine speed ENG1, and as a result, the maximum shaft output STMAX at the accelerator opening ACC at that time can be obtained.

If it is determined in step 207 of the conditional region control routine that the region is in the second feedforward control region, the process proceeds to the second process in FIG. 20 (c).
Move to the feedforward control routine. When the processing shifts to this routine, first, in step 501, the target gear ratio RF2 for the throttle opening SLO at that time is calculated based on the map G of FIG. Then, in the following step 502, the step motors 29A and 29B are feedforward-controlled at high speed so that the gear ratio RF becomes the target gear ratio RF2 calculated in step 501, and the subsequent processing is temporarily terminated.

As described above, in the second feedforward control routine, the target gear ratio RF1 is controlled on the region boundary line which is the upper limit of the feedback control region. Therefore, after the start of traveling, the gear ratio RF does not become maximum even though the throttle opening SLO is low. As a result, it is possible to prevent the vehicle speed V from rapidly increasing, which is not intended by the driver, and the operability can be greatly improved.

Next, the inching control during traveling will be described. FIG. 21 is a flowchart showing a processing routine of inching control executed by the controller 61 in the present embodiment, and this processing is executed during traveling.

When the processing shifts to this routine, first in step 601, the pintle position sensors 31A, 3
Based on the detection result of 1B, the eccentricity amounts δA and δB of the pintles 32 and 14 are read. In the next step 602, the brake depression amount BRK is read based on the detection result of the brake sensor 44.

In step 603, it is determined whether the brake depression amount BRK is less than 70%. And
When the brake depression amount BRK is less than 70%, the process proceeds to step 604.

In step 604, the coefficient Kα is calculated based on the map H. This coefficient Kα is the map G
It is a value multiplied by the target gear ratio RF2. Next, in step 605, the target gear ratio RF2 is multiplied by the coefficient Kα determined based on the map H, and the value is set as a new target gear ratio RF2.

Then, in step 606, the step motors 29A and 29B are drive-controlled so that the gear ratio RF becomes the target gear ratio RF2. That is, the controller 61 feed-forward-controls the step motors 29A and 29B so that the value thereof becomes smaller than the target gear ratio RF2 at the time of the second feed-forward control described above, and temporarily terminates the subsequent processing.

On the other hand, in step 603, when the brake depression amount is 70% or more, the routine proceeds to step 607, where it is judged that the driver has made a sudden stop request, and the target gear ratio RF1 or Set RF2 to zero.

Then, in step 608, the step motor 29A is driven and controlled at high speed so that the eccentricity amount δA of the pintle 32 on the hydraulic pump 3 side becomes zero.
The subsequent processing is once ended. Along with this, the eccentricity amount δA of the pintle 29A on the pump side is quickly returned to zero, and the forklift is stopped.

As described above, in the inching control of the present embodiment, for example, when performing so-called inching traveling, which is a cargo handling work (a work of operating the lift lever or the tilt lever to move the fork up and down and tilting) while traveling. With the accelerator pedal 41 depressed, the brake pedal 43 is depressed to perform the above-mentioned inching control. That is, the gear ratio RF is reduced, and the load on the engine 1 is reduced. Therefore,
Target engine speed EN for the vehicle speed V at that time
G1 becomes higher than that when the brake pedal 43 is not depressed. As a result, the engine speed E required for running
With NG secured, it is possible to obtain the engine speed ENG required for cargo handling work, and thus smooth inching travel becomes possible.

When the brake depression amount BRK is 70% or more, as described above, the gear ratio RF approaches zero at high speed regardless of the knob position, and the forklift is quickly decelerated.

Next, the deceleration feeling control will be described. FIG. 22 is a flowchart showing a processing routine of deceleration feeling control executed by the controller 61 in this embodiment. It should be noted that this processing routine is executed when the degree of deceleration is detected to be equal to or higher than a predetermined value while the vehicle is traveling.

First, in step 701, the knob position of the feeling adjustment knob 49 at that time is read based on the detection result from the knob sensor 50. In the next step 702, the rotational speeds SMA and SMB of both step motors 29A and 29B with respect to the knob position of the feeling adjusting knob 49 read in step 701 are calculated based on the map I.

In the following step 703, the rotation speeds SMA and SMB are set as the rotation speeds of both step motors 29A and 29B, and the subsequent processing is temporarily terminated.
Therefore, for example, when the vehicle is traveling in the feedback control range and the feeling adjustment knob 49 is in the SOFT position at that time, the step motors 29A and 29B are at the lowest speed (1 step / ST). Driven. Therefore, when the accelerator opening ACC is zero, the gear ratio RF approaches zero at the lowest speed, so the forklift is slowly stopped. Further, when the position of the feeling adjusting knob 49 at that time is HARD, the step motors 29A and 29B are set to the highest speed (10st).
ep / ST). Therefore, the accelerator opening AC
When C is zero, the gear ratio RF approaches zero at the lowest speed, so the forklift is immediately stopped.

When the brake depression amount BRK is 70% or more, as described above, the gear ratio RF approaches zero at high speed regardless of the knob position, and the forklift is quickly decelerated and stopped.

Thus, in the deceleration control of this embodiment, the rotational speeds SMA and SMB of both step motors 29A and 29B with respect to the position of the feeling adjusting knob 49 are set during deceleration. For this reason, when the accelerator pedal is stepped down and the vehicle is decelerated while the vehicle is traveling in the feedback control range, if the feeling adjustment knob 49 is located at the SOFT side at that time, the step motors 29A and 29B are It will be driven at the lowest speed, and if it is on the HARD side, step motor 29
A and 29B will be driven at the highest speed. Therefore,
By adjusting the feeling adjusting knob 49, it is possible to experience the deceleration feeling according to the driver's preference.

As described above, in the condition-based region control of this embodiment, the condition is the first feedforward control region X.
When the forklift starts, the step motors 29A and 29B are driven and controlled at a low speed when the speed increase rate requested by the driver is relatively small. Therefore, at the start of traveling of the forklift, the forklift can be smoothly started if it is desired to travel at a very low speed. Further, since the gear ratio RF is feed-forward controlled on the basis of the map E, it is possible to quickly start and accelerate the vehicle without delaying the depression of the accelerator pedal 41, and it is possible to greatly improve the response.

Further, when the condition is in the feedback control area Y, the maximum axis output control is performed.
That is, in the maximum shaft output control, the target engine speed ENG1 calculated by the maximum shaft output control is the engine speed ENG controlled in the main control.
The gear ratio RF is changed so that the load is applied to the engine 1 to obtain the maximum shaft output STMAX. That is, since the engine speed ENG at that time is controlled by the feedback control so as to become the target engine speed ENG1, it is possible to obtain the maximum shaft output STMAX at the accelerator opening ACC at that time.

Further, in the feedback control area Y,
Since the upper limit is set, the gear ratio RF reaches the feedback control region Y after the start of traveling, and thereafter, the second ratio
Even if the vehicle enters the feedforward control region Z, the target gear ratio RF2 does not exceed the upper limit of the feedback control region. As a result, it is possible to prevent a rapid increase in the vehicle speed V against the driver's intention, and it is possible to further improve the operability of the forklift.

Further, in the inching control, when the inching running is performed, the accelerator pedal 41 is depressed and the brake pedal 43 is depressed, whereby the target engine speed ENG with respect to the vehicle speed V at that time.
1 can be made higher than that when the brake pedal 43 is not depressed. As a result, the engine speed ENG required for traveling can be secured, and the engine speed ENG required for cargo handling work can also be obtained, so that inching traveling can be performed smoothly.

Further, in the deceleration feeling control, when the brake pedal 43 is depressed during deceleration of the forklift and the depression amount BRK is less than 70%, the position of the feeling adjustment knob 49 (SOFT) at that time is set. ~ HARD), the rotation speeds SMA and SMB of both step motors 29A and 29B are changed appropriately.

Therefore, the driver can decelerate according to the feeling that the driver sometimes demands, and the operability of the forklift at the time of deceleration can be further improved. When the depression amount BRK is 70% or more, the step motors 29A and 29B are rotated at the highest speed regardless of the position of the feeling adjusting knob 49. Therefore, when a rapid deceleration request is made, the speed can be quickly reduced.

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 maximum shaft output control, the area control, the inching control and the deceleration feeling control are performed in addition to the engine speed control which is the main control. It may be configured such that only the main control and the inching control are performed, and it does not depart from the gist of the present invention even if other controls are not particularly executed.

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

(4) In the above embodiment, the brake depression amount B
When RK is 70% or more, the maximum speed is step motor 2
9A and 29B are set to be drive-controlled, but the numerical value is not particularly limited, for example, 50% or more or 8
You may change suitably, such as 0% or more.

(5) The boundary line of each area in the above embodiment may be changed appropriately.

[0102]

As described in detail above, according to the inching traveling control device for an industrial vehicle equipped with the radial cylinder type variable displacement pump / motor of the present invention, the operation amount of the brake pedal based on the brake operation amount detecting means is changed. Accordingly, the second pintle drive control means drives and controls the pintle drive means so that the gear ratio at that time becomes smaller than that when the brake pedal is not operated, so that inching traveling can be performed smoothly. It has an excellent effect that it can be done.

[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 the shaft output with respect to the engine speed is experimentally obtained.

FIG. 9 is a map in which a target engine speed with respect to an accelerator opening is set.

FIG. 10 is a map in which a feedback coefficient for a gear ratio is set.

FIG. 11 is a map in which each control region divided based on a throttle opening and a gear ratio is set.

FIG. 12 is a map in which a target gear ratio with respect to a throttle opening when executing the first feedforward region control is set.

FIG. 13 is a map in which a target gear ratio with respect to a throttle opening when executing the second feedforward region control is set.

FIG. 14 is a map in which a coefficient for multiplying a target gear ratio with respect to a brake depression amount is set.

FIG. 15 is a graph showing a target speed ratio newly set by multiplying a target speed ratio by a coefficient.

FIG. 16 is a map in which a motor rotation speed is set for a knob position.

FIG. 17 is an explanatory diagram illustrating a control flow.

FIG. 18 is a flowchart showing a processing operation during main control executed by the controller.

FIG. 19 is a flowchart showing the processing operation of region control for each condition, which is executed by the controller.

FIG. 20 is a flowchart showing a processing operation executed by a controller, wherein (a) shows a processing routine of feedforward area control, and (b) shows a processing routine of feedback area control (maximum axis output control). , (C) show other area control processing routines.

FIG. 21 is a flowchart showing a processing operation during inching travel control executed by a controller.

FIG. 22 is a flowchart showing a processing operation during deceleration feeling control executed by the 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 a pintle drive means, 27 ... Control rod which comprises a pintle drive means, 29A, 29B ... Pintle Step motor constituting drive means, 41 ... Accelerator pedal, 42 ... Accelerator sensor as accelerator opening detection means, 43 ... Brake pedal, 44 ... Brake sensor as brake operation amount detection means, 51 ... Valve as valve drive means Step motor, 61 ... Pintle drive control means, target opening calculation means, valve drive control means, controller as second pintle drive control means, RF
... Gear ratio, δA, δB ... Eccentricity.

Claims (1)

[Claims] 1. A radial cylinder type variable displacement pump / motor driven by an engine to drive driving wheels, and an eccentric amount of a pintle provided on the variable displacement pump / motor for controlling a gear ratio of a vehicle by displacement. A pintle drive means for changing the throttle valve opening degree, an accelerator opening degree detecting means for detecting an operation amount of an accelerator pedal operated to control an opening degree of a throttle valve, a valve driving means for opening and closing the throttle valve, and the accelerator. Target opening calculation means for calculating the target opening of the throttle valve based on the detection result of the opening detection means, and a valve for driving and controlling the valve driving means based on the target opening calculated by the target opening calculation means. Drive control means, and a pintle that drives and controls the pintle drive means based on the target opening calculated by the target opening calculation means. A travel control device for an industrial vehicle having a radial cylinder type variable displacement pump / motor having drive control means, comprising: a brake pedal; a brake operation amount detection means for detecting an operation amount of the brake pedal; and a brake operation amount. Second pintle drive control means for driving and controlling the pintle drive means so that the gear ratio at that time becomes smaller than that when the brake pedal is not operated according to the operation amount of the brake pedal based on the detection means. A travel control device for an industrial vehicle, which is provided with a radial cylinder type variable displacement pump / motor.