JPH02275177A - Running control device in engine vehicle which furnishes variable capacity hydraulic pump for variable speed - Google Patents

Abstract

PURPOSE:To allow the inching control easily by reading the regulating data of the oil pressure power responding to the engine rotation frequency to the accelerator operation amount from a memory device, and regulating and controlling a releasing capacity regulating device depending on the regulating data. CONSTITUTION:A controller 29 calculates the operation amount of an accelerator pedal 10 from the signal of an accelerator operation amount sensor 28, and at the same time, a regulating data of the oil pressure power responding to the rotation frequency of an engine 1 to the operation amount is red from a memory device, depending on which, the releasing amount of a charge pump 4 is controlled through a motor 17b for regulation, an inching lever 20, and a reducing valve 17, so that the generation of the oil pressure responding to the engine rotation frequency is transferred to the higher engine rotation side as the accelerator operation amount is increased. And when the accelator pedal 10 is not operated, the charge pump 4 is regulated and controlled to generate the oil pressure power at the higher engine rotation area. In such a way, an inching running can be carried out easily, and a stable stopping operation can be guaranteed by preventing an error starting.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a travel control device for an engine vehicle equipped with a variable displacement hydraulic pump.

[Prior Art] In general, industrial vehicles such as forklifts that are driven by a hydraulic system having a variable capacity hydraulic pump whose discharge capacity is controlled by adjusting the swash plate angle using a charge pump are shown in Fig. 8. It has the configuration shown in.

That is, a charge pump 42 and a variable capacity traveling hydraulic pump 43 are connected to the engine 41, and both pumps 42.
43 rotates following the rotation of the engine 41. The travel hydraulic pump 43 supplies hydraulic oil to the left and right travel hydraulic motors M, causing them to rotate in forward and reverse directions.

Hydraulic oil having a pressure proportional to the rotational speed of the engine 41 flows into the pressure reducing valve 44 from a charge pump 42 connected to the engine 41 . After the pressure reducing valve 44 reduces the pressure of this hydraulic oil in proportion to the discharge amount of the charge pump 42,
This reduced pressure hydraulic oil is made to flow into the passage pipe 46 on the downstream side as a pilot fluid.

Furthermore, the position of the forward/reverse valve 45 is determined by operating the forward/reverse lever 52 either forward or backward. And pressure reducing valve 4
The pilot fluid passing through the passage pipe 46 extending from the swash plate control cylinder 47 flows into either the front chamber or the rear chamber defined by the piston 48 of the swash plate control cylinder 47 based on the switching position of the valve 45, and enters into the other chamber. The pilot fluid that had been staying inside is discharged to the drain side. The swash plate of the traveling hydraulic pump 43 is connected to the cylinder rod 49 of the swash plate control cylinder 47, and the pressure difference between the front chamber and the rear chamber,
The tilt angle and direction of the swash plate are controlled by the balance with the force of the spring 50 that tries to return the piston 48 to the center within the cylinder 47.

Therefore, as the rotation speed of the engine 41 increases, the swash plate angle of this running oil leg pump 43 increases and the discharge capacity increases, and conversely, as the rotation speed decreases, the swash plate angle decreases and the discharge capacity decreases. It is supposed to be done.

When the accelerator pedal 54 connected to the throttle lever 53 of the engine 41 is depressed, the engine 41 rotates at a rotational speed corresponding to the amount of depression, thereby rotationally driving the travel hydraulic pump 43. Furthermore, when the indenter par 57 connected to the spool 55 of the pressure reducing valve 44 via the indenter par 56 is depressed, the pilot pressure is lowered by the movement of the spool 55 according to the amount of depression, and the swash plate of the hydraulic pump 43 is lowered. returned to the neutral side.

[Problems to be Solved by the Invention] A forklift equipped with the above-mentioned hydraulic system is capable of performing inching travel in which the vehicle speed is kept low and the engine 41 is rotated with high torque, such as when traveling upward on a slope. To do this, the driver depresses the inching pedal 57 at the same time as the accelerator pedal 54 to increase the rotational speed of the engine 41, lower the biloft pressure, reduce the swash plate angle of the travel hydraulic pump 43, and increase the discharge capacity. Lower the vehicle and drive at a lower speed.

However, during this inching drive, the accelerator pedal 53 and the inching pedal 57 are pressed simultaneously, which causes physical strain on the driver and causes fatigue. Furthermore, it is difficult to properly press down the accelerator pedal 54 and inching pedal 57 to perform inching driving, and if the amount of depression of both pedals 54,57 becomes large, the engine 41 will rotate at a higher speed than necessary, resulting in reduced fuel consumption. This leads to unnecessary consequences.

In order to solve the above-mentioned problems, an object of the first invention of the present application is to perform inching control without putting a physical burden on the driver, thereby reducing driver fatigue, and furthermore, preventing the engine from operating at an unnecessarily high engine speed. It is an object of the present invention to provide a travel control device for an engine vehicle equipped with a variable speed variable displacement hydraulic pump that can avoid rotation and realize low fuel consumption.

In addition to the object of the first invention, the object of the second invention of the present application is to provide an engine vehicle equipped with a variable displacement hydraulic pump that prevents erroneous starting of the vehicle and ensures stable stopping. An object of the present invention is to provide an inching device.

[Means for Solving the Problems] In order to achieve the above-mentioned object, the first invention of the present application includes a variable displacement hydraulic pump connected to an engine and driven by the engine, and controlling the discharge displacement of the hydraulic pump. a drive means for driving the discharge capacity adjustment means with a hydraulic pressure relative to the engine rotation speed so that the discharge capacity of the hydraulic pump follows the engine rotation speed; In an engine vehicle equipped with a variable speed variable displacement hydraulic pump comprising a hydraulic motor driven by discharged hydraulic oil to rotate a driving drive wheel, an accelerator operation operated to instruct the rotation speed of the engine. means, an accelerator operation amount detection means for detecting the operation amount of the accelerator operation means, and generation of hydraulic pressure relative to the engine rotation speed of the drive means shifts toward a higher engine rotation speed as the accelerator operation amount increases. As shown in FIG. The gist thereof is to provide a control means for reading out adjustment data of the relative hydraulic pressure from the storage means and adjusting and controlling the driving means based on the adjustment data.

A second invention of the present application also provides a variable displacement hydraulic pump connected to an engine and driven by the engine, a displacement adjusting means for controlling the displacement of the hydraulic pump, and a displacement adjusting means for controlling the displacement of the hydraulic pump according to the engine rotation speed. a driving means for driving the discharge volume adjusting means with a hydraulic pressure relative to the engine rotational speed so as to follow the engine rotational speed; and a hydraulic motor that is driven by hydraulic oil discharged from the hydraulic pump to rotate the driving drive wheels. An engine vehicle equipped with a variable displacement hydraulic pump for variable speed, comprising: an accelerator operating means operated to instruct the rotational speed of the engine; an accelerator operating amount detecting means detecting an operating amount of the accelerator operating means; As the accelerator operation amount increases, the generation of hydraulic pressure relative to the engine rotation speed of the drive means shifts toward a high engine rotation speed, and when the accelerator operation means is not operated, the hydraulic pressure is in a high engine rotation range. The accelerator operation amount is determined by the storage means storing the adjustment data of the force of the hydraulic pressure relative to the engine rotation speed with respect to the accelerator operation amount, and the accelerator operation amount detection means, and the engine rotation relative to the operation amount is determined so that the accelerator operation amount is determined. The gist of the present invention is to provide a control means for reading adjustment data of the hydraulic pressure relative to the number from the storage means and adjusting and controlling the driving means based on the adjustment data.

[Function] By employing the above-mentioned means, in the first invention of the present application, the operation amount of the accelerator operation means that indicates the engine speed is detected by the accelerator operation amount detection means. The control means determines the accelerator operation amount according to the detection result of the accelerator operation amount detection means, and reads from the storage means adjustment data of hydraulic pressure relative to the engine rotational speed for the operation amount,
Based on the adjustment data, the drive means is adjusted and controlled so that the generation of hydraulic pressure relative to the engine speed shifts toward a higher engine speed as the accelerator operation amount increases.

Further, in the second invention of the present application, in addition to the first invention, the control means determines the accelerator operation amount according to the detection result of the accelerator operation amount detection means, and adjusts the hydraulic pressure relative to the engine rotation speed with respect to the operation amount. The data is read from the storage means, and based on the adjustment data, the generation of hydraulic pressure relative to the engine speed shifts toward higher engine speeds as the accelerator operation amount increases, and when the accelerator operation means is not operated, The drive means is adjusted and controlled so that hydraulic pressure is generated in a high engine rotation range.

[Example] Hereinafter, a first example in which the present invention is embodied in a hydraulic circuit for a forklift will be described in detail with reference to FIGS. 1 to 5.

As shown in FIG. 1, a cargo handling pump 3, a charge pump 4, and a traveling hydraulic pump 5 as a variable displacement hydraulic pump are connected in this order to an output shaft 2 of an engine 1. The throttle lever 6 of the engine 1 includes a lift lever 7,
A tilt lever 8 and an accelerator pedal 10 as an accelerator operation means are connected, and the engine 1 rotates at a rotational speed according to the amount of operation of these, thereby driving each of the pumps 3 to 5.

The travel hydraulic pump 5 is a two-way type swash plate type variable displacement hydraulic pump motor, and the direction in which the hydraulic oil flows in the travel pipes 5a and 5b is selected depending on the direction of inclination of the swash plate. Rotate the right-hand power running hydraulic motors l, m, and Rm in forward and reverse directions. Further, the discharge capacity of the travel hydraulic pump 5 is adjusted so that it increases when the inclination angle of the swash plate (swash plate angle) is large, and decreases when the swash plate angle is small, and the adjusted discharge capacity and the pump The traveling motor oil pressures Lm and Rm are rotationally driven at a speed according to the rotational speed of 5.

The rotation of the hydraulic motors Lm and Rm rotates drive wheels (not shown), so that the forklift truck travels.

A swash plate control cylinder 13 as a discharge capacity adjusting means is arranged adjacent to the traveling hydraulic pump 5, and its cylinder rod 14 is connected to the swash plate of the traveling hydraulic pump 5. The swash plate angle of the traveling hydraulic pump 5 is adjusted by this movement of the cylinder rod 14. Inside the cylinder 13 is a piston 1 provided on a cylinder rod 14.
The cylinder 13 is divided into a front chamber and a rear chamber at 4a, and the piston 14a is always kept at approximately the center in the longitudinal direction of the cylinder 13 by a pair of push springs S mounted from each side wall of the cylinder 13 to the corresponding side surface of the piston 14a. held in position.

The charge pump 4 discharges a quantity of hydraulic oil into the charge pipe 15 based on the rotational speed of the engine 1. The charge pipe 15 communicates with a pressure reducing valve 17 via an orifice 16, and the pressure reducing valve 17 reduces the pressure of the hydraulic fluid discharged by the charge pump 4. Then, the pressure-reduced hydraulic oil flows out as a pilot fluid into the pilot fluid passage pipe 18 extending from the pressure reducing valve 17 to the forward/reverse movement valve 19. Therefore, although the pilot pressure Pr of the pyrofluid 7) flowing out into the passage pipe 18 is reduced by the pressure reducing valve 17, it increases in proportion to the rotational speed of the charge pump 4, that is, the engine 1.

A charge pump 4 is connected to the spool 17a of the pressure reducing valve 17.
One end of an indenter par 20 constituting a driving means is connected thereto, and the other end of the indenter par 20 is connected via a rod 20a to a motor shaft of a pilot pressure adjusting electric motor 17b.

Then, by the rotation of the adjustment electric motor 17b, the inverter par 20 is tilted, and the operating angle 1r
The pilot pressure Pr of the pilot fluid flowing into the passage pipe 18 is controlled by.

Therefore, it is controlled by the engine speed NO and the operating angle 1r. In this embodiment, the pilot pressure Pr for each operating angle Ir with respect to the engine speed No.
is preset as shown in FIG.

For example, when the operating angle 1r is zero, the biloft pressure Pr
is when the engine speed Ne is at an operating angle from idling to A (the accelerator pedal 10 is at an operating angle of 25% for starting the no-load engine 1 from the idling state, which will be described later), and the no-load speed of the engine 1 is 25%. The pilot pressure Pr is zero until the corresponding value), and the rotational speed Ne is from 8 to B (the operating angle of the accelerator pedal 10 up to 50% during no-load operation of the engine 1, which will be described later), and when the engine 1 is under no-load. The pilot pressure Pr increases in proportion to the engine speed Ne until the engine speed Ne reaches a value equivalent to 25%, and when the engine speed Ne exceeds B, the biloft pressure Pr is always maintained at 100% regardless of this value. It is now possible to do so.

When is Ad, the engine speed Ne changes from the idling state to C (a value corresponding to 75% of the no-load speed specified by the accelerator pedal operating angle of 75% during no-load operation of engine 1, which will be described later). The pilot pressure Pr is zero, and the engine rotation speed Ne is from C to D (the no-load rotation speed instructed by the operation angle of the accelerator pedal 10 at 100% during no-load operation of the engine 1 described later corresponds to 100%). value), the pilot pressure P' increases in proportion to the engine speed Ne, and when the engine speed Ne exceeds D, the pilot pressure Pr is always maintained at 100% regardless of the engine speed Ne. It has become.

The value of the operating angle Ir of the indenter par 20 from zero to Ad is calculated by a controller 29, which will be described later.

Therefore, when the operating angle Ir of the indenter par 20 is held constant, the pilot pressure Pr is 100%.
The discharge capacity of the travel hydraulic pump 5 increases in proportion to the engine rotational speed Ne until reaching the engine speed Ne.

In this embodiment, a stepping motor is used as the adjustment motor 17b, and when the controller 29 (to be described later) outputs a number of pulse signals in accordance with the arrangement of the accelerator pedal IO ff1Acc, the angle (indenter pedal 2'') based on this number of pulses is 0 (corresponding to the operating angle 1r).

Furthermore, the indenter puller 20 is biased toward the vehicle's brake F side by the tension spring 12, and is held at the original position by the biasing force of the tension spring 12 when the drive control of the adjustment motor 17b is released. There is.

The passage pipe 18 passes through a forward/reverse valve 19 located at a forward position (a position) or a reverse position (b position), and then branches into a pair of front and rear pilot pipes 18a, 18b. The front chamber or the rear chamber of the swash plate control cylinder 13 is connected to the front chamber or the rear chamber of the swash plate control cylinder 13 by one of the pilot conduits 18a and 18b selected according to the forward/reverse position switching of the swash plate control cylinder 19. Further, among these pilot pipes 18a, 18b, those which are not communicated with the four-pass pipe 18 are communicated with the drain tank D via the forward/reverse valve 19. Note that when the forward/reverse valve 19 is in the neutral position, the pilot pipes 18a, 18
b is cut off from the passage pipe 18 and the drain tank D.

A cylinder 13 is installed in the pilot pipes 18°a and 18b.
Orifices 21 are provided immediately before the input boats, and the viroft fluid whose flow rate is regulated by these orifices 21 is pumped into the front chamber or rear chamber of the cylinder 13. Further, as shown in the figure, when the forward/reverse valve 19 is in the forward position, the swash plate is inclined in the forward direction, and as the rotational speed Ne of the engine l increases, the pilot pressure Pr from the pressure reducing valve 17 increases, and the pilot pressure Pr from the pressure reducing valve 17 increases. Pressure Pr
At , the cylinder rod 14 moves to the left and the swash plate angle increases.

Further, when the forward/reverse valve 19 is in the reverse position, the swash plate is held tilted in the reverse direction, and the rotational speed Ne of the engine 1 is
As described above, the pilot pressure Pr increases.
increases, and with this pilot pressure Pr, the cylinder rod 1
4 moves to the right and the swash plate angle increases.

Furthermore, the charge pipe line 15 is branched into a replacement pipe line 24 downstream of the orifice 16, and a removal pipe line 25 extending from the pressure reducing valve 17 is communicated with the replacement pipe line 24. After the hydraulic oil flowing from the charge pump 4 into the replacement pipe 24 is filtered by a filter 26, the pressure reducing valve 27 is opened when the replacement pipe 24 is overloaded, and the hydraulic oil flows into the running pipes 5a and 5b. The temperature of the hydraulic oil in the traveling pipes 5a and 5b is mixed with the hydraulic fluid flowing through the traveling hydraulic pump 5 and the traveling hydraulic motors l, m, and Rm, and the temperature is increased by Vfil. lower.

Next, the electrical configuration in this embodiment will be explained.

The accelerator operation amount sensor 28, which serves as an accelerator operation amount detection means, is constituted by a potentiometer, and detects the depression angle of the accelerator pedal 10, and outputs the detection signal to a controller 29, which serves as a control means and a storage means.

The engine rotation speed sensor 30 consists of a pitch-up coil, detects the rotation speed of the engine 1 at any given time, outputs the detection signal to the controller 29, and the controller 29 detects the engine rotation speed Ne at that time. Let it be calculated.

The brake operation amount sensor 31 is composed of a potentiometer, detects the depression operation angle of the brake pedal 11, and outputs the detection signal to the controller 29. The forward/reverse position sensor 33 is composed of a limit switch, detects the forward, backward, and neutral positions of the forward/reverse lever 9, and outputs this detection signal to the controller I/roller 29. Further, the inching lever angle sensor 34 is composed of a potentiometer, detects the current angle (operation angle 1r) of the inching lever 20, and outputs this detection signal to the controller 29.

The controller 29 determines the amount of depression of the brake pedal 11 based on the signal from the brake operation amount sensor 31, and controls the brake pedal 2 based on the determined amount of depression.
The angle at which 0 should be operated is calculated, and the adjustment motor 17b is driven based on the result of this calculation. Further, the controller 29 determines the operation position of the forward/reverse lever 9 according to the signal from the forward/reverse position sensor 33, and switches the forward/reverse valve 19 to one of three positions: forward, neutral, and reverse.

The controller 29 determines the current accelerator operation fiAcc based on the detection signal from the accelerator operation amount sensor 28, and also calculates the target operation angle [acc] of the inverter par 20 with respect to the accelerator operation amount Acc.

In this embodiment, the calculation of the target operating angle 1acc of the inverter par 20 is performed by determining the no-load rotational speed of the engine 1 experimentally or theoretically in advance with respect to the accelerator operation amount Acc, as shown in FIG. The target operating angle 1ace relative to the rotational speed is also determined experimentally or theoretically. Therefore, the target operation angle [acc] of the indenter puller 20 can be uniquely determined with respect to the accelerator operation ff1Acc.

To explain in more detail, the accelerator production amount cc
The accelerator operation amount Acc is 5 from the non-depressing position where is O%.
In the distance up to the 0% depression position, the inch diameter par 20
The target operating angle 1acc becomes zero.

When the accelerator operation amount Ace is at the depression position of 100%, the target operation angle Iacc is set to Ad. Then, at a depression position where the accelerator operation 1iAcc is between 50% and 100%, the target operation angle 1acc is determined by the following calculation formula.

1acc=Ad-Acc/100If this is converted into a no-load rotational speed, the following equation is obtained: 1acc=Ad-Nacc/100.

Therefore, the inch diameter par 20 obtained as above
At each target operating angle 1ace, the engine speed Ne
The pilot pressure Pr changes as shown in FIG.

The controller 29 controls the calculated inching lever 20.
The target operating angle 1acc is compared with the operating angle 1r of the inching lever 20 at that time, and when the re-operating angles [acc and Ir are equal, the adjustment motor 17b is held in a stopped state. The controller 29 also controls the target operating angle 1acc and the operating angle 1r of the indenter par 20.
If they do not match, calculate the corrected operation angle 1cor by calculating the difference between the re-operation angle 1acc and [r,
Adjustment motor 17b according to this corrected operation angle 1cor
to accurately tilt the inch lever 20 to a target operating angle of 1 acc.

Now, the operation of the forklift travel control system configured as described above will be explained with reference to a flowchart showing the operation of the controller 29 in FIG. 5.

Now, when the forklift is running, in step (hereinafter simply referred to as S) Sl, the controller 29 controls the operation amount Acc of the accelerator pedal IO at that time.
is calculated based on the signal from the accelerator operation amount sensor 28, and the accelerator operation 11 is calculated as shown in FIG.
It is determined whether the no-load rotation Nacc with respect to Acc is greater than or equal to B (%) (S2). Then, when the no-load rotational speed Nacc with respect to the accelerator operation amount Acc at that time is less than 8, the target operation angle 1ac of the inch lever 20 is
Set c to zero (S3). On the other hand, when the no-load rotational speed Nacc with respect to the accelerator operation amount Acc at that time is 8 or more, a target operation angle 1acc is calculated based on the following calculation formula (S4).

1acc= A d - Nacc/ 100 Furthermore, Ad
is the value of the target operation angle [acc] at the time of maximum (100%) depression operation of the accelerator pedal 10, and is set in advance.

Target operation angle 1ac for accelerator operation ff1Acc
When c is determined, in order to set the operating angle 1r of the inching lever 20 to the target operating angle 1acc, the actual operating angle 1r of the inching lever 20 at that time is determined based on the detection signal from the inching lever angle sensor 34 in S5. and calculate it. Subsequently, in S6, the controller 29 compares the actual operating angle 1r at that time and the target operating angle 1acc, and if Ir = Iacc, that is, the actual operating angle 1r is equal to the target operating angle 1acc. Therefore, in S7, the adjustment morph 17b is held in that state without being rotated, and the process returns to Sl.

On the other hand, when Ir #1acc, the controller 29
It is determined in S8 whether the target operating angle 1ace is smaller than the operating angle 1r, and if it is smaller, the adjustment motor 17b is rotationally driven in S9 so that the operating angle Ir of the inching lever 20 becomes larger. On the contrary, if the target operating angle 1acc is larger than the operating angle 1r, the controller 29 controls the inverter par 20 in S10.
Adjustment motor 17b so that the operating angle 1r of
drive the rotation. Therefore, based on the rotational drive of the adjustment motor 17b, the indenter puller 20 adjusts Ir=Iacc.
As a result, the adjustment motor 17b is held stopped in that state in S7, and the state of Ir=Iacc is held.

In this way, the operation angle 1r of the inchindarepago 20 is controlled based on the operation IAcc of the accelerator pedal IO, and the set operation angle 1r (=target operation angle 1acc) is controlled.
The pilot pressure Pr will take a value between zero and 100% depending on the engine rotational speed Ne at that time. Therefore, depending on the rotation speed of the engine 1, the traveling hydraulic pump 5
The discharge capacity of the fuel will be controlled.

That is, the operation of the accelerator pedal 10 (iAcc is set to the maximum (1)
00%) (when the no-load rotation speed Nacc corresponds to D), Iacc (-=Ir) is A from the above formula.
It becomes d. At this time, since the pilot pressure Pr is determined by the characteristic line of Ir=Ad as shown in Fig. 3,
In the high rotation range (high torque range) of the engine 1, it is possible to achieve a state in which the speed of the vehicle is from low to high.

Furthermore, when the operation 1Acc of the accelerator pedal 10 corresponds to the no-load rotation speed Nacc which is less than or equal to B, the target operation angle 1acc (-operation angle 1r) of the engine lever 20 is
=O, and the pilot pressure Pr is determined by the characteristic line of the operating angle 1r=O as shown in FIG. Therefore,
When the rotation speed of the engine 1 is A, the pilot pressure Pr
is zero and the vehicle speed is also zero, and in the rotation range from A to B, the vehicle speed of the forklift gradually increases as the rotation speed increases.

In this way, in this embodiment, unlike conventional cargo handling vehicles such as forklifts, the engine l can be controlled in each rotational range by operating only the accelerator pedal 10, without relying on the two operating means of the inflator and the accelerator pedal. A wide range of vehicle speeds from low to high speeds can be obtained.

Furthermore, by adopting a configuration in which the inverter par 20 is biased toward the original position by the tension spring 12, the adjustment motor 17b, the accelerator operation amount sensor 28, and the controller 2
If any malfunction occurs in various parts such as 9, etc.,
0 is held at the position where the operating angle 1r=0. Therefore, when the engine 1 rotates at a rotational speed exceeding B, the pilot pressure Pr does not become 0, and the vehicle can run reliably despite malfunctions of various parts.

Next, the separate parts of this invention will be explained according to FIG. 6.7.

In this embodiment, the target operation angle 1acc of the indentation lever 20 is set based on the accelerator operation amount cc as shown in FIG. In other words, when the accelerator pedal 10 is not operated, the adjustment motor 17b is driven to set the target operating angle Ir = taax of the inflator 20, and even though the accelerator pedal 10 is not operated, the rotational speed Ne of the engine 1 is changed for some reason. Even when the forklift reaches a high speed range, the pilot pressure Pr is always maintained at 0 to prevent the forklift from starting.

Then, as shown in FIG. 7, following step S2, the controller 29 determines whether or not the no-load rotational speed Nacc corresponding to the accelerator operation amount Acc is O in the determination in 5101, and if it is not 0, the controller 29 proceeds to S3. When the target rotational speed Nacc is 0, the target operating angle I ace -taax of the indenter puller 20 is set in step 5102, and the process proceeds to S5, where the same processing as in the first embodiment is performed.

As described above, by adding two steps to the program of the first embodiment, it is possible to maintain the pilot pressure Pr at O even if the engine l is rotated for some reason when the accelerator pedal 10 is not operated. Since the swash plate of the traveling hydraulic pump 5 is maintained in a neutral state and the discharge capacity is 0, the vehicle will not malfunction.

Note that this invention is not limited to the above-described embodiments, and any changes may be made without departing from the spirit of the invention, such as using another electric motor instead of the stepping motor for the adjustment motor 17b. Can be operated without electricity.

[Effects] As detailed above, the first invention of the present application enables inching driving without putting a physical burden on the driver and causing fatigue, and also reduces fuel consumption by avoiding unnecessarily high rotation of the engine. It becomes possible to realize the

Further, the second invention of the present application exhibits an excellent effect of preventing erroneous starting of the vehicle and ensuring stable stopping operation.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram showing the hydraulic and electrical configuration in the first embodiment of the present invention, Fig. 2 is a diagram showing the relationship between the accelerator operation amount and the no-load rotation speed of the engine, and Fig. 3 is a diagram showing the relationship between the accelerator operation amount and the no-load rotation speed of the engine. Figure 4 shows the swash plate angle that is controlled by the inch diameter puller angle for each actual rotational speed of the engine. FIG. 5 is a flowchart showing the operation of the controller; FIG. 6 is a diagram showing changes in the operating angle of the inverter when the pilot pressure is set to O in the second embodiment of the present invention; FIG. FIG. 7 is a flowchart showing the operation of the controller in the second embodiment, and FIG. 8 is a hydraulic circuit diagram showing a conventional example. An engine 1, a charge pump 4 as a driving means, a traveling hydraulic bomb 5 as a variable displacement hydraulic pump, an accelerator pedal 10 as an accelerator operating means, a swash plate control cylinder 13 as a discharge capacity adjusting means, and an inch as a driving means. controller 29 as a control means and storage means, an accelerator operation amount sensor 28 as an accelerator operation amount detection means, and hydraulic motors Lm and Rm. Patent applicant Toyota Industries Corporation representative
Patent Attorney On 1) Hironobu (and 1 other person) Diagram Accelerator operation f ¥ 1 ACC Diagram Engine rotation speed Ne Diagram Mugen rotation speed Nacc Diagram Muji rotation speed Nacc

Claims (1)

[Scope of Claims] 1. A variable displacement hydraulic pump connected to an engine and driven by the engine; Discharge capacity adjusting means for controlling the discharge capacity of the hydraulic pump; a driving means for driving the discharge volume adjusting means with hydraulic pressure relative to the engine rotational speed so as to follow the rotational speed of the engine; and a hydraulic motor that is driven by the hydraulic oil discharged from the hydraulic pump and rotates the traveling drive wheels. An engine vehicle equipped with a variable displacement hydraulic pump for variable speed, comprising: an accelerator operation means operated to instruct the rotation speed of the engine; and an accelerator operation amount detection means for detecting the operation amount of the accelerator operation means. and adjustment data of the hydraulic pressure relative to the engine rotation speed relative to the accelerator operation amount so that the generation of the hydraulic pressure relative to the engine rotation speed of the drive means shifts toward a higher engine rotation speed as the accelerator operation amount increases. The accelerator operation amount is determined by the accelerator operation amount detection means, and adjustment data of the hydraulic pressure relative to the engine rotational speed for the operation amount is read from the storage means, and based on the adjustment data, the accelerator operation amount is determined. A travel control device for an engine vehicle equipped with a variable speed variable capacity hydraulic pump comprising a control means for adjusting and controlling a drive means. 2. a variable displacement hydraulic pump connected to an engine and driven by the engine; a displacement adjusting means for controlling the displacement of the hydraulic pump; A variable speed motor comprising: a drive means for driving the discharge capacity adjusting means with a hydraulic pressure relative to the engine rotational speed; and a hydraulic motor driven by hydraulic oil discharged from the hydraulic pump to rotate a driving drive wheel. An engine vehicle equipped with a variable displacement hydraulic pump, comprising: an accelerator operating means operated to instruct the rotational speed of the engine; an accelerator operating amount detecting means detecting an operating amount of the accelerator operating means; In such a way that the generation of hydraulic pressure relative to the engine rotation speed shifts toward higher engine rotation speeds as the accelerator operation amount increases, and the hydraulic pressure is generated in a high engine rotation range when the accelerator operation means is not operated.
A storage means that stores adjustment data of hydraulic pressure relative to the engine rotation speed with respect to the accelerator operation amount, and an accelerator operation amount detection means that determines the accelerator operation amount and adjusts the oil pressure relative to the engine rotation speed with respect to the operation amount. An inching device for an engine vehicle equipped with a variable speed variable capacity hydraulic pump, comprising control means for reading pressure adjustment data from a storage means and adjusting and controlling the drive means based on the adjustment data.