JPH02283533A - Speed control device of engine vehicle equipped with variable volume hydraulic pump for variable speed - Google Patents

Abstract

PURPOSE:To perform stable running, and to secure good drive operational feeling by correcting variation of vehicle speed in accordance with operation quantity on an accelerator at a time of loading operation performed when the accelerator is operated. CONSTITUTION:An engine 1 drives a loading pump 3, a charge pump 4 and a variable capacity hydraulic pump 5 for running, and a vehicle runs with right and left hydraulic motors Rm, Lm for running. A controller 29 reads out adjusting data of hydraulic force corresponding to engine revolution speed from a memory means 29a based on an accelerator pedal's 10 operation quantity detected by an accelerator operation quantity detecting means 28, and controls the charge pump 4 via an inching lever 20. If actual engine speed detected by a sensor 30 is varied by loading operation in relation to engine speed for accelerator operation quantity here, adjusting data of hydraulic force for the charge pump 4 are corrected, to correspond to accelerator operation quantity. Thus, stable running can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a vehicle speed adjustment device for an engine vehicle equipped with a variable speed 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. 7. 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 re-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 . Then, the pressure reducing valve 44 reduces the pressure of the hydraulic oil in proportion to the discharge amount of the hydraulic oil from the charge pump 42, and then flows the reduced pressure hydraulic oil 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 pressure passing through the passage pipe 46 extending from 4 flows into either the front chamber or the rear chamber defined by the piston 48 of the swash plate angle control cylinder 47 based on the switching position of the valve 45, and The pilot fluid remaining inside the other side is discharged to the drain side. The swash plate of the traveling hydraulic pump 43 is connected to the cylinder loft 49 of the swash plate angle control cylinder 47, and the pressure difference between the front and rear chambers and the spring 50 that tries to return the piston 48 to the center within the cylinder 47 are connected to the cylinder loft 49 of the swash plate angle control cylinder 47. The tilt angle and tilt direction of the swash plate are controlled by the balance with the force.

Therefore, in this traveling hydraulic pump 43, as the rotational speed of the engine 41 increases, the swash plate angle increases and the discharge capacity increases, and conversely, as the rotational speed decreases, the swash plate angle decreases and the discharge capacity decreases. It looks like this.

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. Further, when a lift lever 55 and a tilt lever 56 connected to the throttle lever 53 of the engine 41 are operated in the same manner as the accelerator pedal 54, the engine 41 rotates at a rotation speed corresponding to the amount of operation, and the cargo handling pump 57 is rotated. to drive.

[Problems to be Solved by the Invention] However, when the vehicle is running, that is, when the accelerator pedal 54 is depressed, when it becomes necessary to perform a cargo handling operation such as raising and lowering the fork, and the lift lever 55 is operated, the accelerator pedal 54 is depressed. The engine 41 rotates at a rotational speed based on the amount of operation of the lift lever 55 in addition to the amount of operation of the lift lever 55. Then, as the engine speed increases, the swash plate angle of the travel hydraulic pump 43 increases and the discharge capacity increases, thereby driving the travel hydraulic motor M to rotate at a rotation speed equal to or higher than the accelerator operation amount. do.

For this reason, during cargo handling operations, the vehicle speed increases faster than the speed instructed by the driver by operating the accelerator, and shock is transmitted to the vehicle, which impedes stable driving and impedes a good driving feel. becomes.

This invention was made to solve the above-mentioned problems, and its purpose is to quickly correct fluctuations in vehicle speed according to the amount of accelerator operation when cargo handling operations are performed during accelerator operation, so that stable driving can be achieved. An object of the present invention is to provide a speed control device for an engine vehicle equipped with a variable displacement hydraulic pump for variable speed, which can ensure good driving performance.

[Means for Solving the Problems] In order to achieve the above-mentioned objects, the present invention provides a variable displacement hydraulic pump connected to an engine and driven by the engine, and a discharge displacement for controlling the discharge displacement of the hydraulic pump. an adjusting means; a driving means for driving the discharge capacity adjusting means with a hydraulic pressure relative to the rotation speed of the engine so that the discharge capacity of the hydraulic pump follows the engine rotation speed;
In an engine vehicle equipped with a variable displacement variable displacement hydraulic pump comprising a hydraulic motor driven by hydraulic oil discharged from the hydraulic pump and rotating a driving drive wheel, the variable displacement hydraulic pump is operated to instruct the rotation speed of the engine. an accelerator operation means for detecting the operation amount of the accelerator operation means; an engine rotation speed detection means for detecting the rotation speed of the engine; a storage means for storing adjustment data of the hydraulic pressure with respect to the amount, and an accelerator operation amount detection means for determining an accelerator operation amount, and reading from the storage means adjustment data of the hydraulic pressure relative to the engine rotation speed for the operation amount. a control means for adjusting and controlling the drive means based on the data; a determining means for determining whether the actual engine speed detected by the rotation speed detection means exceeds the engine speed relative to the accelerator operation amount; and a correction means for correcting the adjustment data of the hydraulic pressure with respect to the operation amount in order to make the vehicle speed relative to the accelerator operation amount when the determination means determines that the actual engine rotation speed exceeds the engine rotation speed corresponding to the accelerator operation amount. The gist of this article is as follows.

[Function] When the operation amount of the accelerator operation means is detected by the accelerator operation amount detection means, the adjustment data of the hydraulic pressure relative to the engine rotation speed for this operation amount is read from the storage means, and the drive means is adjusted based on this data. Controlled by control means. Then, the determining means determines whether or not the actual engine rotation speed detected by the engine rotation speed detection means exceeds the engine rotation speed relative to the accelerator operation amount. When it is determined that the number exceeds the accelerator operation amount, the correction means corrects the adjustment data of the hydraulic pressure with respect to the operation amount so as to make the vehicle speed relative to the accelerator operation amount.

[Embodiment 1] An embodiment in which the present invention is applied to a hydraulic circuit of a forklift will be described in detail below with reference to FIGS. 1 to 6.

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 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 inclination direction of the swash plate. Rotate the rightward travel hydraulic motors Lm and Rm in forward and reverse directions. Further, the discharge capacity of the traveling 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. Traveling motor hydraulic pressures Lm and Rm are driven at a speed according to the rotational speed of the hydraulic pump 5.

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 is adjusted.

The inside of the swash plate control cylinder 13 is divided into a front chamber and a rear chamber by a piston 14a provided on a cylinder loft 14,
The piston 14a is always held at approximately the center of the cylinder 13 by a pair of push springs S mounted on the piston 14a from each side wall of the cylinder 13.

The charge pump 4 discharges hydraulic fluid into the charge pipe 15 in an amount based on the rotational speed of the engine 1. A pressure reducing valve 17 is provided in the charge pipe 15 via an orifice 16 to reduce the pressure of the hydraulic oil discharged by the charge pump 4. Then, the pressure-reduced hydraulic oil flows out as a pilot fluid into a pilot fluid passage conduit 18 extending from the pressure reducing valve 17 to the forward/reverse movement valve 19.

A charge pump 4 is connected to the spool 17a of the pressure reducing valve 17.
An inching lever 20 constituting a driving means is connected with the inching lever 20, and the inching lever 20 is connected to an electric motor 1 for adjustment.
It is connected to the motor shaft 7b via a loft 20a.

The rotation of the electric motor 17b causes the inverter par 20 to be tilted, and the pilot pressure Pr of the pilot fluid flowing into the passage pipe 18 is controlled by the operating angle 1r. Therefore, the pilot pressure Pr is controlled by the engine speed and the operating angle 1r. In this embodiment, the pilot pressure Pr for each operating angle Ir with respect to the engine speed is preset as shown in FIG.

For example, when the operating angle 1r of the inverter par 20 is zero, the engine speed changes from the idling state to A (the operating amount is 25% when the accelerator pedal 10 starts from the idling state during no-load conditions, which will be described later), and the no-load speed (rotational speed corresponding to 25%), the pilot pressure P
r is zero, and the engine speed is from A to B (the accelerator pedal IO at no-load, which will be described later, is 50% operation amount after starting from idling, and the no-load speed is 5).
The pilot pressure Pr increases in proportion to the engine speed until the engine speed corresponds to 0%, and when the engine speed is equal to or higher than B, the viroft pressure Pr is always 100% regardless of this value.

In addition, when the operating angle 1r of the inverter par 20 is A40, the engine speed changes from the idling state to C (the accelerator pedal 10 at no-load state, which will be described later, is 75% of the operating amount after starting from the idling state, and the no-load speed (rotational speed corresponding to 75%), the pilot pressure P
r is zero, and the engine rotation speed is from C to D (the rotation speed at which the accelerator pedal 10 at no load, which will be described later, is 100% operation amount after starting from idling, and the no-load rotation speed corresponds to 100%) ), the pilot pressure Pr increases in proportion to the engine speed, and when the engine speed is D or higher, the pilot pressure Pr is always 100% regardless of this value.
becomes.

The value of 0-Ad of this operating angle 1r is calculated by a controller 29, which will be described later.

Therefore, when the operating angle 1r of the inverter par 20 is constant, the discharge capacity of the travel hydraulic pump 5 increases in proportion to the engine speed until the pilot pressure Pr reaches 100%.

The passage pipe 18 is in the forward position (position a) or in the backward position!
After passing through the forward/reverse valve 19 located at position (b), it branches into a pair of front and rear pilot pipes 18a and 18b, and this passage pipe 18 is connected to one of the biloft pipes selected according to the forward/reverse position switching of the forward/reverse valve 19. Roads 18a and 18b
This communicates with the front chamber or rear chamber of the swash plate control cylinder 13. Further, among these pilot pipes 18a and 18b, those which are not communicated with the passage 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.

An orifice 21 is provided in each of the pilot conduits 18a and 18b immediately before the input port of the swash plate control cylinder 13, and a pilot fluid whose flow rate is regulated by these orifices 21 is sent into 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 engine speed increases, the pilot pressure from the pressure reducing valve 17 increases, and this pilot pressure causes the cylinder to rod 1
4 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 as the rotational speed of the engine 1 increases, the pilot pressure increases in the same manner as described above.
The biloft pressure moves the cylinder rod 14 to the right, increasing the swash plate angle.

Further, 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. The hydraulic oil flowing from the charge pump 4 into the replacement pipe line 24 is filtered by a filter 26, and then the pressure reducing valve 27 is opened when the pipe line is overloaded. Then, this hydraulic oil is mixed into the hydraulic oil in the traveling pipes 5a and 5b,
The temperature of the oil in the traveling conduits 5a, 5b, which has been raised by circulating between the traveling hydraulic pump 5 and the traveling hydraulic motors Lm, Rm, is lowered.

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

The accelerator operation amount sensor 28 is composed of a potentiometer, detects the depression angle of the accelerator pedal 10 (accelerator operation amount Acc), and sends the detection signal to the control means,
Controller 2 as a judgment means and a correction means
Output to 9. An engine rotation speed sensor 3° serving as an engine rotation speed detection means is composed of a pink amplifier coil, detects the rotation speed of the engine 1 (actual rotation speed Ne), and outputs a detection signal thereof to the controller 29.

The brake operation amount sensor 31 is made of a potentiometer, and the 0-reverse movement position sensor 33, which detects the depression angle of the brake pedal 11 and outputs the detection signal to the controller 29, is made of a limit switch, and the forward-reverse movement lever 9
The forward, backward, and neutral positions of the vehicle are detected and the detection signals are output to the controller 29. Further, the inch lever angle sensor 34 is composed of a potentiometer, detects the operating angle 1r of the inch 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 operates the inch lever 2 based on the determined amount of depression.
0 calculates the angle to be manipulated. Furthermore, 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 pulp 19 to one of three positions: forward, neutral, and reverse.

The controller 29 determines the accelerator operation amount Acc at that time based on the signal from the accelerator operation amount sensor 28, and also calculates the target operation angle 1acc of the inch lever 20 with respect to this operation amount Acc. In this embodiment, the target operation angle 1acc of the engine lever 20 is calculated by experimentally or theoretically determining the engine rotational speed (no-load rotational speed Nacc) for only the accelerator operation amount Acc as shown in FIG. Furthermore, as shown in FIG. 3, the target operating angle 1a for this no-load rotation speed Nacc is
Similarly, cc is determined experimentally or theoretically in advance. Data regarding this is stored in advance in a memory 29a built in the controller 29 as a storage means.

Therefore, the target operation angle 1ace can be uniquely determined with respect to the accelerator operation amount Acc.

To explain in more detail, the accelerator operation amount Ace is 0.
The target operating angle 1ace of the inching lever 20 is set to zero between the % non-depression position and the 50% depression position. When the accelerator operation amount Acc is at the depression position of 100%, the target operation angle 1acc is set to Ad. Then, at a depression position where the accelerator operation amount Acc is from 50% to 100%, the target operation angle 1acc is determined by the following calculation formula.

Iacc = Ad ・ Acc / 1 0 0 If this is converted to the no-load rotation speed Nacc, the following formula is obtained: Iacc = Ad - Nacc / 100 ・・・・■
becomes.

This target operation angle 1ace means that when the rotation speed Ne of the engine 1 becomes equal to or higher than the rotation speed relative to the accelerator operation amount Acc (no-load rotation speed Nacc), the pilot pressure Pr becomes 100%; At the number Ne, the pilot pressure Pr is the target operating angle 1acc=O (or Ad)
increases or decreases at the same rate.

Therefore, the pilot pressure Pr with respect to the engine rotational speed at each target operating angle 1 ace thus determined is as shown in FIG. 4 described above.

The controller 29 also controls the actual rotational speed Ne of the engine l when the cargo handling lever or the like is operated.
When the rotation speed (no-load rotation speed Nacc) based on only the operation amount Acc is exceeded, the target operation angle 1ace of the inching lever 20, which is uniquely determined with respect to the operation amount cc, is corrected. This prevents the vehicle speed based on the driver's operation of the accelerator pedal IO from becoming unintended due to the increase in rotational speed due to the operation of the cargo handling control lever and the increased pyro-/) pressure Pr. This is to prevent this.

This correction processing operation differs depending on the accelerator operation amount Acc at that time.

When the accelerator operation amount Acc is between zero and 25%, the target operation angle 1ace is zero and the pilot pressure Pcl that corresponds to this is zero, and the actual rotational speed Ne of the engine l is the target rotational speed, that is, the no-load rotational speed Nacc. Even if the bialoft pressure Pr increases above this value, it is necessary to maintain the bialoft pressure Pr at zero, that is, to maintain the vehicle speed at zero.

Therefore, at the target operating angle 1acc determined for each no-load rotational speed Nacc, the increase in rotational speed at that time ΔN
(= Ne - Nacc) to determine a new target operating angle 1rx. In other words, the rotation speed (-Na
cc+ΔN) as the new corrected target rotational speed Nx, the target operating angle 1rx for the target rotational speed Nx shown in FIG. 3.4 is determined.

Therefore, the target operation angle 1rx does not become zero even if the accelerator operation amount Ace is from 0% to 25%, and the increase ΔN
, and the pilot pressure Pr is held at zero.

Next, when the accelerator operation amount Acc is between 25% and 50%, the target operation angle 1acc is zero, and the pilot pressure Pr increases at a constant ratio to the actual rotation speed Ne (from A to B). Since the vehicle starts moving and reaches a speed Vx, it is necessary to maintain the vehicle speed vx.

Vehicle speed Vx is determined by rotation speed Ne and pilot pressure Pr (swash plate angle)
Since it is proportional to the product of Vx = -Pr.Ne .--. is a constant.

Therefore, when the target operation angle 1acc is zero, the no-load rotation speed Nac corresponding to the accelerator operation amount Acc at that time.
The controller 2 controls the pilot pressure Pcl determined for c.
9, the vehicle speed Vl at that time is -Pc1.Nacc...■.

Then, since it is necessary to set Vx-Vl, that is, ■-■, k・P
r-Ne- becomes -Pcl-Nacc...■, and the biloft pressure P to make the vehicle speed Vl when the rotation speed is Ne
r(Pc2) becomes Pc2-Pal-Nacc/Ne...■.

Therefore, when the rotation speed is Ne0, the new target operating angle 1rx (=I a
cc).

Therefore, the engine speed (
The function of the no-load rotation speed Nacc) is Pcl x a (N
acc - 1 acc) + b Note that a is the slope, b is the intercept, and the no-load rotation speed Nac with respect to accelerator operation amount cc
Target operating angle 1a for c and no-load rotation speed Nacc
It is determined in advance like cc.

Also, in this case, since 1acc=0, Pc1-a
-Nacc+b...■.

On the other hand, the engine speed Ne with respect to the biloft pressure Pc2
The function is Pc2=a (Ne-1rx) +b...-
■It becomes. Then, the target operating angle 1rx is obtained from 2000 as follows.

lrx = a (Ne-Nacg) + b(N
e −Nacc) a−Ne ...■ Therefore, the target operation angle 1acc is the accelerator operation amount Acc
is from 25% to 50%, even if the engine speed Ne increases to more than the engine speed Nacc based on the operation of the accelerator pedal IO due to the operation of the cargo handling lever, etc., the target operating angle 1acc will be corrected to the value found in 2〇. By doing this, the vehicle speed Vx is determined by the vehicle speed ν that is determined by the operation of the accelerator pedal 10.
It is held at 1.

Next, when the accelerator operation amount Acc is the operation amount of 50% or more, the target operation angle 1acc is calculated from the formula (■) as Iacc=Ad −
Since Nacc/100...■ and the pilot pressure Pr is 100%, it is necessary to maintain the vehicle speed Vx at that time at vl.

Vl = k - Pcl ・Nacc pilot pressure P
cl is the maximum (100%), and if this is 1, then Vl = k - Nacc.

Then, as before, Vx = Vl to k l'r
-Ne=k -Nacc, and in order to make the vehicle speed vl when the rotational speed is Ne, the pilot pressure Pr (=P
c2) becomes Pc 2 = Nacc/Ne.

Therefore, the above formula 〇 is Pc2 = a (Ne-1rx) + b = Na
cc/Ne, Irx = (a −Ne−Nacc+ b)a
-Ne ・ ・ ・ ・■
becomes.

Therefore, if the operating angle is 1 acc, the accelerator operating amount Acc is 5.
0% or more, even if the engine speed Ne increases to more than the engine speed Nacc based on the operation of the accelerator pedal 10, the vehicle speed Vx can be adjusted to the accelerator pedal lO by correcting the operation angle 1acc to the value obtained by formula (■). The vehicle speed is maintained at v1 depending on the operation.

Now, the operation of the vehicle speed adjusting device configured as described above will be explained below with reference to FIG.

Now, in step (hereinafter simply referred to as S) Sl, based on the signal from the accelerator operation amount sensor 28 and the signal from the engine rotation speed sensor 30, the controller 29 determines the no-load rotation speed of the engine 1 with respect to the accelerator operation amount Acc at that time. That is, the target rotational speed Nacc and the actual rotational speed Ne are calculated.

Then, in S2, the target rotational speed Nacc is compared with the actual rotational speed Ne, and when Nacc≧Ne, it is determined that no cargo handling operation is being performed and normal control is executed.On the contrary, the actual rotational speed Ne is When the target rotational speed Nacc is exceeded, it is determined that the engine rotational speed has increased based on the cargo handling operation, and it is determined in S3 whether the target rotational speed Nacc is lower than the rotational speed A in FIG. 3.

When it is below, the engine 1 determines that at least the accelerator operation amount Acc is 25% or more, and then in 84 it is determined whether the target rotational speed Nacc is equal to or less than B.

When the target rotational speed Nacc exceeds B, it is determined that the target rotational speed Nacc is 50% or more, and in S5, the formula (■), that is, Irx = (a - Ne - Nacc + b) / (a
-Ne), the target operation angle 1rx is calculated.

Then, when a signal from the inching lever angle sensor 34 that has detected the operating angle 1r of the inching lever 20 is inputted in S6, the controller 29 controls the operating angle 1r in S7.
It is determined whether or not r and the target operating angle 1rx are equal, and if they are equal, the inverter par 20 is held in the current state without driving the electric motor 7b for adjustment in S8.

When the target operating angle 1rx and the operating angle 1r differ in S7, the operating angle 1r becomes the target operating angle 1rx in S9.
It is determined whether or not the difference is larger, and if it is larger, the SIO drives the adjustment electric motor 17b to increase the inclination angle of the inverter par 20 by this difference. Further, when the controller 29 determines in S9 that the operating angle 1r is smaller than the target operating angle 1rx, it drives the adjustment electric motor 17b in Sll to reduce the inclination angle of the inverter par 20 by an angle corresponding to the difference.

Further, in S3, the controller 29 controls the target rotation speed Na.
If it is determined that the value of cc is smaller than A, that is, the target rotational speed NaccO value corresponds to the idling region, 312
After calculating the new target rotational speed Nx by calculating the formula (2), that is, Nx=Nacc+ΔN, and determining the corresponding target rotational speed 1rx, the process moves to S6.

Further, in S4, the controller 29 controls the target rotation speed N.
If it is determined that the accO value exceeds B, the target operating angle 1rx is determined in S13 based on the formula (■), and the process proceeds to S6.

As described above, in this embodiment, the rotation speed of the engine 1 is changed by the accelerator operation amount Acc by operating the cargo handling lever.
When the vehicle travels at a speed exceeding the rotational speed Nacc corresponding to the engine speed and higher than the vehicle speed intended by the driver, the pilot pressure is set to vary with each engine rotational speed in order to control the swash plate angle of the travel hydraulic pump 5. The target operating angle 1rx of the inchin lever 20 is determined by the above calculation method.

Then, the operating angle 1r of the inch lever 20 is corrected based on this target operating angle 1rx. Therefore, although the actual rotational speed Ne of the engine 1 exceeds the target rotational speed Nacc and the rotational speed of the travel hydraulic pump 5 increases, the discharge capacity is adjusted by adjusting the swash plate angle according to the angle correction of the engine lever 20. Therefore, the actual vehicle speed Vr is the target vehicle speed V.
It becomes equal to acc. Therefore, the vehicle has accelerator pedal 1
It travels at a speed according to the manipulated variable of 0.

[Effects] As described in detail above, the present invention quickly corrects fluctuations in vehicle speed according to the amount of accelerator operation when a cargo handling operation is performed during accelerator operation, thereby achieving stable driving and good driving operation feel. It has the excellent effect of guaranteeing the ring.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram showing the hydraulic and electrical configuration 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 no-load rotation speed of the engine. Diagram 4 showing the relationship between the angle and the operating angle of the inchin lever.
The figure is a diagram showing the relationship between engine speed and pilot pressure, Figure 5 is a diagram showing how to match the actual engine speed with the target engine speed that instructs idling, and Figure 6 is the action of the controller. FIG. 7 is a hydraulic circuit diagram showing a conventional example. Hydraulic pump 5 for running the engine 11, accelerator pedal IO1 as accelerator operation means, swash plate control cylinder 13 as discharge capacity itgm adjustment means, charge pump 4 and engine lever 20 as drive means, accelerator operation amount detection means An accelerator operation amount sensor 28, a controller 29 as a control means, a judgment means and a correction means, a memory 29a as a storage means, an engine rotation speed sensor 30 as an engine rotation speed detection means. Hydraulic motor Lm. Rm. Patent applicant Toyota Industries Corporation representative
Patent Attorney On 1) Hironobu (1 idiot) Figure Figure Figure Figure Figure No negative rotational 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; Adjustment of the discharge capacity of the hydraulic pump by engine rotation drive means for driving the discharge capacity adjusting means with hydraulic pressure relative to the rotational speed of the engine so as to follow the rotational speed of the engine; In an engine vehicle equipped with a variable speed variable capacity hydraulic pump consisting of a hydraulic motor, an accelerator operating means operated to instruct the rotational speed of the engine, and an accelerator operating amount detecting the operating amount of the accelerator operating means. detection means; engine rotation speed detection means for detecting the rotation speed of the engine; storage means for storing in advance engine rotation speed data for the accelerator operation amount and adjustment data of the hydraulic pressure for the operation amount; and the accelerator operation amount. a control means that determines an accelerator operation amount using a detection means, reads adjustment data of hydraulic pressure relative to the engine rotation speed for the operation amount from a storage means, and adjusts and controls the drive means based on the data; and the rotation speed. Judgment means for determining whether the actual engine rotation speed detected by the detection means exceeds the engine rotation speed relative to the accelerator operation amount; A speed control device for an engine vehicle equipped with a variable displacement hydraulic pump for variable speed, comprising a correction means for correcting the adjustment data of the hydraulic pressure with respect to the operation amount so as to make the vehicle speed relative to the accelerator operation amount when it is determined.