JPH0516708A - Cargo controller in engine-driven vehicle equipped with variable delivery type hydraulic pump for speed change - Google Patents

Abstract

PURPOSE:To control the sharp increase of car speed by operating a driving means by selecting the operation force with which the hydraulic pressure corresponding to the number of engine revolution becomes the least, in substitution for the operation quantity which is calculated in the ordinary traveling, in the selection of mode from the ordinary traveling to the loading traveling. CONSTITUTION:As for an engine 1 for a forklift, the opening degree of an engine throttle valve is adjusted through a lever 39 by the drive of a step motor 38 controlled by a controller 37, and the number of revolution is controlled. In this controller 37, if a lift lever La, etc. are operated, and the opening degree of a throttle valve which is based on the operation becomes larger than the throttle valve opening degree corresponding to an accelerator, it is judged that the transition from the ordinary traveling to the loading traveling is performed. In the selection of mode, the operating power with which the hydraulic pressure corresponding to the number of engine revolution becomes the least is selected in substitution for the operation quantity which is calculated in the ordinary traveling, and a pressure reducing valve 13 as driving means for controlling the delivery adjusting means 8 of a hydraulic pump 5 for traveling is operated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cargo handling control device for an engine vehicle equipped with a variable speed variable displacement hydraulic pump.

[0002]

2. Description of the Related Art The present applicant has conventionally proposed various engine vehicles such as forklifts equipped with a variable displacement hydraulic pump (Japanese Laid-Open Patent Publication Nos. 2-247684 and 2-245572).

This type of vehicle is constructed as follows, for example. That is, as shown in FIG. 6, a cargo handling pump 3, a charge pump 4 and a traveling hydraulic pump 5 as a variable displacement hydraulic pump are sequentially connected to the output shaft 2 of the engine 1. An accelerator pedal 7 is connected to the throttle lever 6 of the engine 1, and the throttle lever 6 connected to the throttle valve tilts in accordance with the operation amount of the accelerator pedal 7 (accelerator operation amount). The engine 1 rotates at a rotation speed associated with the above, and the pumps 3 to 5 are driven.

The traveling hydraulic pump 5 is a two-way type swash plate type variable displacement hydraulic pump. The direction in which the hydraulic oil flows in the traveling pipe lines 5a, 5b is selected by the inclination direction of the swash plate, and the left side is selected. The traveling hydraulic motors Lm and Rm as the left and right hydraulic motors are rotated in the forward and reverse directions to drive a pair of left and right drive wheels (not shown) connected to the traveling hydraulic motors Lm and Rm. Further, the displacement of the traveling hydraulic pump 5 is adjusted to be large when the tilt angle (swash plate angle) of the swash plate is large and to be small when the swash plate angle is small. Then, the traveling hydraulic motors Lm, Rm are driven at a rotational speed according to the discharge amount of the traveling hydraulic pump 5 (increases / decreases according to the rotational speed of the traveling hydraulic pump 5 at the discharge capacity defined by the swash plate angle). It

A servo cylinder 8 as a discharge capacity adjusting means is disposed adjacent to the traveling hydraulic pump 5, and a piston rod 9 of the servo cylinder 8 is provided.
Are connected to the swash plate of the traveling hydraulic pump 5, and the angle of the swash plate is adjusted by the movement of the piston rod 9. The inside of the servo cylinder 8 is divided into a front chamber 10a and a rear chamber 10b by a piston 9a provided on a piston rod 9, and a pair of push springs S mounted on the piston 9a from each side wall of the servo cylinder 8 normally Sometimes the piston 9a is the servo cylinder 8
It is held in the central position. That is, at this time, the swash plate angle becomes zero and the discharge capacity of the traveling hydraulic pump 5 becomes zero.

The charge pump 4 discharges an amount of hydraulic oil based on the rotation speed (engine speed) of the engine 1 into the charge conduit 11. The charge conduit 11 is provided with a pressure reducing valve 13 via an orifice 12 so as to reduce the pressure of the hydraulic oil discharged by the charge pump 4. Then, from the pressure reducing valve 13, the pressure-reduced working oil flows out as a pilot fluid to the pilot fluid passage line 15 extending to the forward / reverse valve 14.

An inching lever 16 which constitutes a driving means together with the pressure reducing valve 13 is connected to the spool 13a of the pressure reducing valve 13, and the inching lever 16 is connected to the motor shaft of the stepping motor 13b via a rod 16a. ing. And the stepping motor 13b
The inching lever 16 is tilted relative to the rotation amount of the pilot pressure P flowing into the pilot fluid passage 15 by the tilt angle, that is, the operation angle Ir.
r is controlled. Therefore, the pilot pressure Pr is controlled by the engine speed and the operation angle Ir.

In general, the pilot pressure Pr for each operation angle Ir with respect to the engine speed is preset so as to be as shown in FIG. That is, for example,
When the operation angle Ir of the inching lever 16 is zero, the engine speed is A from the idling state (the accelerator pedal 7 at the time of no load, which will be described later, is 25% of the operation amount starting from the idling state, and the no-load rotational speed is Up to 25% (see FIG. 8) (see FIG. 8), the pilot pressure Pr increases in proportion to the engine speed, and the engine speed changes from A to B (accelerator pedal 7 in an idling state under no load described later). The pilot pressure Pr is always 100% irrespective of the engine speed up to 50% of the operation amount after the engine is started and the unloaded rotation speed corresponds to 50%.

Further, the operating angle I of the inching lever 16
When r is Ad, the engine speed changes from the idling state to C (according to the accelerator pedal 7 under no load described later).
Is a 75% manipulated variable after starting from the idling state, the pilot pressure Pr is zero until the no-load rotational speed corresponds to 75%), and the engine rotational speed is from C to D.
The pilot pressure Pr is proportional to the engine speed until (the accelerator pedal 7 at the time of no-load, which will be described later, starts from an idling state and the operation amount is 100%, and the no-load rotational speed corresponds to 100%). When the engine speed is D or higher, the pilot pressure Pr is always 100% regardless of the engine speed. The values 0 to Ad of the operation angle Ir are calculated by the controller 18 described later.

The forward / reverse valve 14 has a forward position (a
Position) or reverse position (b position) or neutral position (c position)
There are three positions, which can be switched through the controller 18 by operating the forward / backward lever 17. The pilot fluid passage line 15 is branched into a pair of front and rear pilot lines 15a and 15b. If the forward / reverse valve 14 is in the forward position, the pilot line 15b is provided.
To the rear chamber 10b of the servo cylinder 8 and, if the forward / reverse valve 14 is in the reverse position, the pilot line 15
The front chamber 10a of the servo cylinder 8 is communicated with each other via a. Further, among these pilot conduits 15a and 15b, those that are not communicated with the pilot fluid passage conduit 15 are communicated with the drain tank D through the forward / reverse valve 14. When the forward / reverse valve 14 is in the neutral position, the pilot lines 15a and 15b are shut off from the pilot fluid passage line 15 and the drain tank D.

In the pilot lines 15a and 15b,
Immediately before the input port of the servo cylinder 8, the orifices 19a and 1a for preventing abrupt fluctuations of the discharge amount, respectively.
9b is provided, and the pilot fluid of which the flow rate is regulated is sent into the servo cylinder 8 by these orifices 19a and 19b. Further, a detour conduit 20 that bypasses the orifice 19b and is connected to the rear chamber 10b of the servo cylinder 8 is provided in the rear pilot conduit 15b, and electromagnetic control is performed in the detour conduit 20. A valve 21 is provided. The bypass line 20 and the rear chamber 10b of the servo cylinder 8 are opened or closed by opening and closing the electromagnetic control valve 21.

Thus, when the forward / reverse valve 14 is at the forward position (position a), the pilot pressure from the pressure reducing valve 13 increases as the engine speed increases, and the pilot pressure causes the piston rod 9 to move. Moving to the left, the swash plate angle is largely tilted in the forward direction.
At this time, when the electromagnetic control valve 21 is closed, the pilot fluid flows into the rear chamber 10b of the servo cylinder 8 while the flow rate is restricted by the orifice 19b, and the piston 9a
Is moved slowly. On the other hand, when the electromagnetic control valve 21 is opened, the pilot fluid flows into the rear chamber 10b of the servo cylinder 8 through the bypass conduit 20 and the piston 9a is moved quickly.

Then, the traveling hydraulic pump 5 discharges the hydraulic oil from one of the discharge ports so that the traveling hydraulic motors Lm and Rm can be discharged.
To rotate the engine forward to move the engine vehicle such as a forklift forward.

When the forward / reverse valve 14 is in the reverse position (position b), the pilot pressure increases in the same manner as described above due to the increase in the rotation speed of the engine 1, and the pilot pressure causes the piston rod 9 to move to the right. And the swash plate angle is largely tilted in the backward direction. At this time, when the electromagnetic control valve 21 is closed, the flow rate of the pilot fluid is restricted by the orifice 19b, and the servo cylinder 8 is controlled.
Flows out of the rear chamber 10b through the orifice 19b,
The piston 9a is moved slowly. On the other hand, the electromagnetic control valve 2
When 1 is opened, the pilot fluid flows out of the rear chamber 10b of the servo cylinder 8 through the bypass line 20, and the piston 9a is moved rapidly.

Then, the traveling hydraulic pump 5 discharges the hydraulic oil from one of the discharge ports so that the traveling hydraulic motors Lm and Rm are discharged.
To reverse the engine vehicle such as a forklift.

A replacement conduit 22 is branched from the charge conduit 11 downstream of the orifice 12, and an exclusion conduit 23 extending from the pressure reducing valve 13 is replaced by the replacement conduit 22.
Is in communication with.

In addition, the charge line 11 includes a filter 24.
And a charge relief valve 25, and is connected to a pair of replenishment circuits 28 including check valves 26a and 26b and relief valves 27a and 27b. The replenishment circuit 28 is connected to the traveling pipelines 5a and 5b, and when the hydraulic pressure in the traveling pipelines 5a and 5b decreases due to leakage of hydraulic oil from the traveling hydraulic pump 5 or the like, the charge pipeline 28 is connected. 11 through the replenishment circuit 28, the pipeline 5a for traveling,
Hydraulic oil is supplied into 5b. Further, the hydraulic oil flowing from the charge pump 4 into the exchange conduit 22 is charged by the charge relief valve 2 when the traveling conduits 5a and 5b are overloaded.
5 is opened and mixed with the hydraulic oil in the traveling pipe lines 5a and 5b, and the traveling hydraulic pump 5 and the traveling hydraulic motors Lm and R are supplied.
The oil temperature of the running pipelines 5a and 5b which is circulated and heated to m is lowered.

The cargo handling hydraulic pump 3 outputs a quantity of hydraulic oil based on the rotational speed of the engine 1 to a cargo handling hydraulic line (not shown). This cargo handling hydraulic line supplies hydraulic oil to cargo handling lift cylinders, tilt cylinders, etc.
The known cargo handling work is possible.

Next, the electrical configuration of this example will be described. The accelerator pedal 7 is provided with an accelerator operation amount sensor 29 composed of a potentiometer, and detects the depression amount of the accelerator pedal 7,
The detection signal is output to the controller 18. Further, the engine 1 is provided with an engine rotation speed sensor 30 as a rotation speed detecting means including a pickup coil, detects the rotation speed of the engine 1, and outputs a detection signal to the controller 18. ..

The brake pedal 31 provided in the driver's seat is provided with a brake operation amount sensor 32 composed of a potentiometer, and the brake pedal 31 is provided.
The amount of stepping on the controller is detected and the detection signal is sent to the controller 1
Output to 8.

The forward / backward lever 17 is provided with a forward / backward position sensor 35 composed of a limit switch, which detects forward, backward and neutral positions of the forward / backward lever 17, and outputs detection signals thereof. Output to the controller 18.

The inching lever 16 is provided with an inching lever angle sensor 36 composed of a potentiometer.
Angle of the controller 1 and the detection signal is detected by the controller 1
Output to 8.

On the other hand, the controller 18 calculates the accelerator operation amount Acc at that time on the basis of the signal from the accelerator operation amount sensor 29, and also determines the accelerator operation amount A.
A target operation angle Iacc of the inching lever 16 corresponding to cc is calculated. The target operation angle Iacc of the inching lever 16 is calculated in advance experimentally or theoretically as shown in FIG. 8 to obtain the engine speed (no-load speed Nacc) corresponding to only the accelerator operation amount.
As shown in, the target operation angle Iacc with respect to the no-load rotational speed Nacc is similarly obtained in advance experimentally or theoretically. The data relating to this is stored in the controller 18 in advance. Therefore, the target operation angle I
acc is uniquely obtained with respect to the accelerator operation amount Acc.

More specifically, the target operation angle Ia of the inching lever 16 is between the non-depressed position where the accelerator operation amount Acc is 0% and the depressed position where the accelerator operation amount is 50%.
Set cc to zero. When the accelerator operation amount Acc is 100% in the depressed position, the target operation angle Iacc is Ad. Then, the accelerator operation amount Acc is 50% to 100.
The target operation angle Iacc at the stepping position of% is calculated by the following arithmetic expression.

Iacc = AdAcc / 100 Incidentally, the following formula is obtained by converting this into the no-load rotational speed Nacc.

Iacc = Ad · Nacc / 100 This target operating angle Iacc is the rotational speed at which the engine speed is relative to the accelerator operation amount Acc (no-load rotational speed Nac
When it becomes equal to or higher than c), the pilot pressure Pr becomes 100%, and at the rotational speed lower than that, the pilot pressure Pr increases and decreases at the same rate as the target operation angle Iacc = 0 (or Ad). Therefore, the operating angle Ir of the inching lever 16
Is controlled so as to reach each of the obtained target operation angles Iacc, the pilot pressure Pr with respect to the engine speed becomes as shown in FIG.

Further, the controller 18 controls the forward / backward lever 17 based on the signal from the forward / backward position sensor 35.
Judging the operating position of, the forward / reverse valve 14 is moved forward, neutral,
Switch to any of the three reverse positions. Further, the controller 18 calculates the angle of the inching lever 16 according to the signal from the inching lever angle sensor 36.

[0028]

By the way, the engine 1
There is a case where the cargo handling traveling work is performed by increasing the rotation speed (engine speed) of the engine and increasing the discharge amount of the cargo handling hydraulic pump 3. In this way, when carrying out cargo handling traveling, the controller 1
As described above, No. 8 controls so that the operating angle Ir of the inching lever 16 also rises as the engine speed rises, but in reality there was a problem as described below. That is, as shown in FIG. 7, for example, Ir = I
It is assumed that the vehicle is normally traveling at rx ₁ and engine speed k ₁ (point α in the figure). Then, it is assumed that the accelerator pedal 7 is depressed to carry out the cargo handling traveling work, and the engine speed is increased to k ₂ . At this time, the operation angle Ir of the inching lever 16 is Ir depending on the depression amount of the accelerator pedal 7.
From x ₁ to Irx ₂ , the pilot pressure Pr becomes point β and the discharge amount of the traveling hydraulic pump 5 is maintained in the previous state.

However, since the operating angle Ir of the inching lever 16 cannot swiftly follow Irx ₂ ,
Even if the engine speed increases, the pilot pressure Pr remains temporarily held at 100% (point β ′ in the figure), that is, the swash plate angle rapidly tilts, and momentarily. There was a risk of shock to the vehicle, such as a sudden increase in vehicle speed. As a result, driving could be unstable.

The present invention has been made in order to solve the above problems, and its purpose is to prevent a shock such as a sudden increase in vehicle speed from occurring during normal to cargo handling travel, and to provide stable operation. An object of the present invention is to provide a cargo handling control device in an engine vehicle equipped with a variable speed variable displacement hydraulic pump capable of performing the cargo handling traveling work.

[0031]

In order to achieve the above object, the present invention provides a variable displacement hydraulic pump driven by an engine, a discharge displacement adjusting means for controlling the displacement of the hydraulic pump, and the hydraulic pump. Drive means for driving the discharge capacity adjusting means with hydraulic pressure relative to the engine speed so as to make the discharge capacity of the engine follow the engine speed,
In an engine vehicle equipped with a variable displacement hydraulic pump for variable speed, which comprises a hydraulic motor driven by hydraulic oil discharged from the hydraulic pump to rotate a drive wheel for traveling, the engine speed is adjusted according to the opening degree. The opening of the throttle valve is determined on the basis of a throttle valve, a rotation drive means for rotating the throttle valve, a cargo handling operation means for performing cargo handling operation, and an operation amount of an accelerator pedal or a cargo handling operation means. An opening degree determination means, a throttle valve rotation drive control means for controlling the rotation of the throttle valve via the rotation drive means so as to achieve the opening degree determined by the opening degree determination means, an accelerator pedal or a cargo handling operation. Judgment means for judging mode switching between normal traveling and cargo handling traveling based on the operation amount of the means, and corresponding to the engine speed at that time A first calculation means for determining the operation amount of the drive means, a second calculation means for determining the operation amount of the drive means based on the operation amount of the accelerator pedal and the engine speed at that time; The drive means is controlled based on the operation amount calculated by the first calculation means, the drive means is controlled based on the operation amount calculated by the second calculation means during the cargo handling traveling, and the determination means is usually When it is determined that the mode has been switched from traveling to cargo handling traveling, within a predetermined time, instead of the operation amount calculated by the first calculation means, the oil pressure relative to the engine speed is the smallest oil pressure. Select the working amount
An object is a cargo handling control device in an engine vehicle equipped with a variable speed variable displacement hydraulic pump, characterized in that an operation control means for operating the drive means based on the selected operation amount is provided.

[0032]

The operation control means controls the drive means on the basis of the operation amount calculated by the first arithmetic means during normal traveling, and the operation control means on the basis of the operation amount calculated by the second arithmetic means during cargo handling traveling. While controlling the driving means, when the judging means judges that the mode has been switched from the normal traveling to the cargo handling traveling, the engine rotation is replaced with the operation amount calculated by the first calculating means within a predetermined time. Select the operating amount that gives the smallest hydraulic pressure,
The drive means is operated based on the selected operation amount. Therefore, when the mode is switched from the normal traveling to the cargo handling traveling, even if the engine speed rises, the operation amount at which the oil pressure corresponding to the engine speed becomes the smallest oil pressure is selected. The drive means is driven based on the operated amount. As a result, the drive means drives faster,
Since the discharge capacity adjustment means does not change significantly and the discharge capacity from the hydraulic pump does not increase, shocks such as sudden increases in vehicle speed do not occur, and the transition from normal travel to cargo handling travel is performed smoothly. .. Further, since the drive means is controlled based on the operation amount calculated by the second calculation means during traveling as cargo, the drive means is adjusted by operating the accelerator pedal, and the vehicle speed is controlled.

[0033]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which a cargo handling control device of the present invention is embodied in a hydraulic circuit of a forklift will be described below with reference to the drawings. Since the present embodiment is embodied in the engine vehicle described in FIG. 6, only different parts will be described for convenience of description.

Although the accelerator pedal 7 is connected to the throttle lever 6 of the engine 1 in FIG. 6,
In the present embodiment, as shown in FIG. 1, the accelerator pedal 7 determines the opening degree together with the lift lever La operated to raise and lower the fork and the tilt lever Lb operated to tilt the mast back and forth. Means, throttle valve rotation drive control means, first calculation means, second calculation means, judgment means, controller 37 as operation control means are electrically connected. The lift lever La and the tilt lever Lb have a lever sensor L.
s is provided, the lever sensor Ls detects the operation amount of each of the levers La and Lb, and the detection signal is the same as in the case of the accelerator operation amount sensor 29.
7 is input.

Further, the engine 1 is provided with a step motor 38 as a rotation driving means, and the step motor 38 is driven by a signal from the controller 37. The throttle lever 3 connected to the engine 1 is driven by the driving of the step motor 38.
9, the throttle valve is opened and closed by this tilting, and the engine speed is controlled.

A map shown in FIG. 2 is previously stored in the controller 37. In this map, the accelerator pedal 7, lift lever La and tilt lever Lb are shown.
The throttle opening of the throttle valve based on each operation amount (forward tilt, backward tilt) is preset. The controller 37 sets the throttle opening degree at that time as the throttle opening degree that has the maximum opening value among the throttle opening degrees based on the respective operation amounts. When the throttle opening based on the operation amount of the accelerator pedal 7 is the maximum, the throttle opening (throttle opening corresponding to the accelerator) is set by the throttle opening based on the operation amount of the accelerator pedal 7. On the other hand, the lift lever La or the tilt lever Lb
When the throttle opening amount based on the operation amount of is the maximum, the throttle opening amount (lever-corresponding throttle opening amount) is set to the maximum throttle opening amount based on the operation amount of the lift lever La or the tilt lever Lb. It is supposed to be set.

Further, the controller 37 prestores the three-dimensional map shown in FIG. In this three-dimensional map, the engine speed at that time (lift lever L
a or an inching lever target operation angle Iacc that is determined from the engine speed (based on the operation amount of the accelerator pedal 7) predicted from the operation amount of the tilt lever Lb) and the accelerator depression amount is set. And
During the cargo handling traveling, the operation angle Ir of the inching lever 16 is controlled according to this three-dimensional map.

On the other hand, during the normal running, the target operation angle Iacc according to the maps shown in FIGS. 8 and 9, that is, corresponding to the engine speed at that time (however, this engine speed is based on the throttle opening corresponding to the accelerator). Set
The operating angle Ir of the inching lever 16 is controlled. Further, the inching lever 16 is operated within a predetermined time (the time required for the inching lever operation angle Ir to be maximum in this embodiment) from the start of the cargo handling traveling.
The target operation angle Iacc is set to be maximum, and the operation angle Ir is controlled.

This will be described with reference to the time chart of FIG. 4. During normal traveling, the target operating angle Iacc is set according to the conventional maps shown in FIGS. 8 and 9, that is, in accordance with the engine speed at that time, and inching is performed. Lever 1
The operation angle Ir of 6 is controlled. Then, after it is determined that the cargo handling is started, the target operation angle Iacc of the inching lever 16 is set to be the maximum, and the actual operation angle Iacc is set.
Control is performed until r becomes maximum. Thereafter, during the cargo handling traveling, the target operation angle Iacc of the inching lever 16 is set according to the three-dimensional map shown in FIG. 3, and the operation angle Ir is controlled. Then, after the end of the cargo handling traveling, the map returns to the conventional map, and the operation angle Ir of the inching lever 16 is controlled.

Next, the operation of this embodiment will be described according to the processing operation of the controller 37. As shown in the flow chart of FIG.
Based on the data map shown in FIG. 2, it is determined whether the current cargo handling traveling mode is set. That is, the throttle opening of the throttle valve based on each operation amount of the accelerator pedal 7, the lift lever La, and the tilt lever Lb (forward tilt, rear tilt) is mutually compared. When the throttle opening corresponding to the accelerator is the maximum, it is not in the cargo handling traveling mode, that is, only traveling, that is, the normal traveling mode, and the process proceeds to step 7 described later.

In step 7, the throttle opening corresponding to the accelerator is set as the throttle opening to adjust the opening of the throttle valve, and in the next step 8,
The target operation angle Iacc of the inching lever 16 is set according to the conventional map shown in FIG. 8 to control the operation angle Ir.

On the other hand, when shifting from normal traveling to cargo handling traveling, that is, the lift lever La and the tilt lever Lb.
If one of (forward tilt, backward tilt) is operated and the throttle opening based on the operation amount (lever corresponding throttle opening) becomes larger than the accelerator corresponding throttle opening, go to step 1. It is determined that the vehicle is in the cargo handling traveling mode, and the process proceeds to the next step 2.

In step 2, of the throttle opening compared in step 1, the largest one is selected,
The throttle opening corresponding to the lever is set as the throttle opening, and the valve opening is adjusted. Therefore, the engine speed increases according to the operation of the cargo handling lever such as the lift lever La and the tilt lever Lb.

Then, in step 3, the target operating angle Iacc of the inching lever 16 is set to the maximum, and the inching lever 16 is controlled until the operating angle Ir of the inching lever 16 becomes the maximum. In the next step 4, it is judged based on the signal from the inching lever angle sensor 36 whether or not the actual inching lever operation angle Ir becomes maximum. If the inching lever operation angle Ir has not reached the maximum yet, the inching lever 1 is used until it reaches the maximum.
The operation angle Ir of 6 is increased. In this case, the larger the target operation angle Iacc is, the higher the speed of rising per unit time is. Therefore, the increase in the operating angle Ir of the inching lever 16 cannot follow the increase in the engine speed as in the conventional case, and the pilot pressure Pr increases, that is, the swash plate angle tilts more and the vehicle speed increases. Things will not happen. That is, by setting the target operation angle Iacc to the maximum until the actual operation angle Ir of the inching lever 16 becomes maximum, the operation angle Ir of the inching lever 16 also rises following the increase in the engine speed. Therefore, the pilot pressure Pr does not increase, and the vehicle speed does not increase.

On the other hand, when it is determined in step 4 that the actual inching lever operation angle Ir has reached the maximum, the process proceeds to the next step 5, and the target of the inching lever 16 is determined based on the three-dimensional map shown in FIG. Operation angle Iacc
Is set to control the operation angle Ir. At this time, that is, the inching lever operation angle Ir during cargo handling traveling
Is determined from the engine speed and the engine speed expected from the accelerator depression amount. Therefore, the operating angle Ir of the inching lever 16 is
The operation angle Ir of the inching lever 16 is adjusted not only by the engine speed determined by the operation of the lift lever La and the tilt lever Lb but also by the depression of the accelerator pedal 7. as a result,
The vehicle speed is adjusted by depressing the accelerator pedal 7.

Next, in step 6, as in the case of step 1, it is judged whether or not the cargo handling is completed based on the data map shown in FIG. If the throttle opening corresponding to the accelerator is smaller than the maximum throttle opening corresponding to the lever so far, it is determined that the cargo handling is still in progress, the process returns to step 5, and based on the three-dimensional map shown in FIG. The target operation angle Iacc of the inching lever 16 is set, the operation angle Ir is controlled, and the cargo handling traveling work is continued.

On the other hand, when returning from the cargo handling traveling to the normal traveling, that is, the lift lever La or the tilt lever L.
When the accelerator-corresponding throttle opening becomes larger than the lever-corresponding throttle opening based on the operation amount by operating either b (forward tilt or rearward tilt) to return to the original state, the cargo handling traveling It is determined that the mode has ended, and in the next step 7, the throttle opening corresponding to the accelerator is set as the throttle opening and the valve opening is adjusted. Then, in the next step 8, the target operation angle Iacc of the inching lever 16 is set according to the conventional map shown in FIG. 7, and the operation angle Ir is controlled.

As described above, in this embodiment, the throttle lever 39 is tilted by driving the step motor 38, and the controller 37 is based on the accelerator operation amount, the lift lever operation amount and the tilt lever operation amount. Since the optimum throttle opening is set, the optimum engine speed based on the accelerator operation and both lever operations can be obtained. Therefore, energy can be saved by setting the engine speed to the minimum necessary, and the switching operation between normal traveling and cargo handling traveling can be smoothly performed.

Further, when carrying out the cargo handling traveling, the inching lever target operation angle Iacc is controlled to be the maximum from the start of the cargo handling traveling until a predetermined time (the time when the inching lever operation angle Ir becomes the maximum). Therefore, the rising speed of the operation angle Ir can be increased. Therefore, even if the engine speed increases, the inching lever operation angle Ir can also be increased following the increase. Therefore, there is no risk that the pilot pressure Pr will rise, that is, there will be no risk of further tilting of the swash plate angle, so there is no risk of a shock being generated in the vehicle due to an instantaneous increase in vehicle speed. As a result, stable cargo handling traveling work can be performed.

Further, during the cargo handling traveling after the lapse of a predetermined time,
Inching lever 1 based on the three-dimensional map shown in FIG.
The operation angle Ir of 6 was controlled. That is, the operation angle Ir of the inching lever 16 can be adjusted not only by the engine speed based on the lever-corresponding throttle opening degree at that time but also by the operation amount of the accelerator pedal 7. Therefore, even during the cargo handling traveling, by depressing the accelerator pedal 7, the operating angle Ir of the inching lever 16 and thus the vehicle speed can be appropriately adjusted.

The present invention is not limited to the above embodiments, but may be configured as follows, for example, within the scope of the invention. (1) The inclinations of the maps shown in FIGS. 2 and 3 may be changed appropriately.

(2) In the above embodiment, a knob or the like for adjusting the acceleration / deceleration feeling may be further provided, and the controller 37 may appropriately duty-control the opening of the electromagnetic control valve 21.

(3) In the above embodiment, the time for setting the inching lever target operation angle Iacc to the maximum is
Although it is the time until the actual inching lever operation angle Ir reaches the maximum, it may be a predetermined time experimentally or theoretically obtained in addition to the time.

[0054]

According to the cargo handling control device for an engine vehicle equipped with the variable displacement hydraulic pump for variable speed according to the present invention, a shock such as a sudden increase in vehicle speed may occur when carrying out cargo handling traveling from normal traveling. It is possible to carry out stable cargo handling traveling work.

[Brief description of drawings]

FIG. 1 is a hydraulic and electric circuit configuration diagram in an engine vehicle equipped with a variable speed variable displacement hydraulic pump of the present invention.

FIG. 2 is a data map that defines a set value of a throttle opening for each operation amount of an accelerator pedal, a lift lever, and a tilt lever.

FIG. 3 is a map showing a target operation angle of an inching lever, which is set based on an engine speed predicted from an engine speed and an accelerator depression amount.

FIG. 4 is a time chart showing a control configuration of an inching lever angle.

FIG. 5 is a flowchart showing a processing operation of a controller.

FIG. 6 is a hydraulic and electric circuit configuration diagram in an engine vehicle including a conventional variable speed variable displacement hydraulic pump.

FIG. 7 is a diagram showing a relationship between pilot pressure and engine speed.

FIG. 8 is a diagram showing a relationship between a no-load rotation speed and an accelerator operation amount.

FIG. 9 is a diagram showing a relationship between an inching lever operation angle and a no-load rotation speed.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Engine, 3 ... Hydraulic pump for cargo handling, 5 ... Hydraulic pump for traveling as variable displacement hydraulic pump, 7 ... Accelerator pedal, 8 ... Servo cylinder as discharge capacity adjusting means, 1
3 ... Pressure reducing valve as drive means, 16 ... Inching lever as drive means, 37 ... Opening degree determination means, throttle valve rotation drive control means, determination means, first calculation means, second calculation means, operation control Controller as a means, 3
8 ... Step motor as rotation driving means, Lm, Rm
... a traveling hydraulic motor as a hydraulic motor, La ... a lift lever as a cargo handling operation means, Lb ... a tilt lever as a cargo handling operation means.

Continuation of the front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display location F16H 59:42 8207-3J

Claims (1)

Claim: What is claimed is: 1. A variable displacement hydraulic pump driven by an engine, a displacement control means for controlling the displacement of the hydraulic pump, and a displacement of the hydraulic pump that follows the engine speed. To drive the discharge capacity adjusting means with hydraulic pressure relative to the engine speed, and a hydraulic motor driven with hydraulic oil discharged from the hydraulic pump to rotate the drive wheels for traveling. In an engine vehicle equipped with a variable displacement hydraulic pump for variable speed, a throttle valve that adjusts the engine speed according to the opening degree, a rotation drive unit that rotates the throttle valve, and a cargo handling operation for performing a cargo handling operation. An operating means; an opening degree determining means for determining an opening degree of the throttle valve based on an operation amount of an accelerator pedal or a cargo handling operating means; The throttle valve rotation drive control means for controlling the rotation of the throttle valve via the rotation drive means and the normal operation based on the operation amount of the accelerator pedal or the cargo handling operation means in order to reach the opening determined by the degree determination means. Judgment means for judging mode switching between traveling and cargo handling, first computing means for deciding the operation amount of the drive means corresponding to the engine speed at that time, and the accelerator pedal at that time Second operation means for determining the operation amount of the drive means on the basis of the operation amount and the engine speed, and the drive means is controlled on the basis of the operation amount calculated by the first operation means during normal traveling to carry out cargo handling. During traveling, the drive means is controlled based on the operation amount calculated by the second calculating means, and the determining means determines that the mode has been switched from normal traveling to cargo handling traveling. , Within a predetermined time, instead of the operating amount calculated by the first calculating means, an operating amount at which the hydraulic pressure corresponding to the engine speed is the smallest is selected, and based on the selected operating amount And a drive control means for operating the drive means, and a cargo handling control device for an engine vehicle equipped with a variable speed variable displacement hydraulic pump.