JPH0315570B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a travel control device for a cargo handling vehicle, and more particularly to a cargo handling vehicle equipped with a prime mover that drives drive wheels and a cargo handling hydraulic pump through a continuously variable transmission. The present invention relates to a travel control device that controls the travel speed of a cargo handling vehicle in a vehicle by varying the gear ratio of a continuously variable transmission.

Conventionally, some cargo handling vehicles equipped with cargo handling equipment, such as forklifts and shovel loaders, have a single engine that drives the drive wheels and drives the cargo handling hydraulic pump via a continuously variable transmission. . This type of cargo handling vehicle has a continuously variable transmission with a torque converter or a hydrostatic continuously variable transmission.

In the case of a torque converter vehicle, when carrying out cargo handling work while traveling at low speeds, the rotation speed of the cargo handling hydraulic pump must be increased, so it is necessary to press the accelerator pedal to rev the engine. At this time, as the rotational speed increases, the vehicle speed increases. Therefore, it was necessary to adjust the vehicle speed by operating the inching pedal to prevent the vehicle speed from increasing.
Therefore, cargo handling operations while the vehicle is running are troublesome and require advanced techniques, and it is extremely difficult to carry out cargo handling operations while compensating for fluctuations in vehicle speed caused by cargo handling operations.

In addition, in a cargo handling vehicle equipped with a hydrostatic continuously variable transmission, the engine is revved similarly to the torque converter vehicle, and the gear ratio is lowered by operating the swash plate operation pedal to maintain a constant vehicle speed, or the engine is used for driving or cargo handling. No matter what, I always left it blowing and adjusted the vehicle speed with the swash plate operation pedal. However, in this case as well, it is very difficult to perform cargo handling operations while compensating for fluctuations in vehicle speed caused by cargo handling operations.Moreover, since the engine is blown regardless of driving or cargo handling operations, noise and fuel consumption are reduced. There was a problem.

The present invention has been made to solve the above problems, and its purpose is to eliminate the need for advanced operating techniques at all when carrying out cargo handling operations while driving, and to prevent fluctuations in vehicle speed based on cargo handling operations. It is an object of the present invention to provide a travel control device for a cargo handling vehicle that can eliminate the need for transportation and improve noise and fuel efficiency.

In order to achieve the above object, the present invention provides a cargo handling vehicle equipped with a cargo handling device, in which a prime mover drives a cargo handling hydraulic pump of the cargo handling device, and the prime mover drives a continuously variable transmission. , a calculating means for calculating a ratio between an amount corresponding to the rotation speed of the prime mover based on the operation of the cargo handling operation device during traveling and an amount corresponding to the rotation speed of the prime mover before the operation, and a calculation means based on the operation of the cargo handling operation device It consists of means for calculating a gear ratio of the continuously variable transmission to compensate for fluctuations in vehicle speed based on the calculated ratio, and a control means for controlling the gear ratio of the continuously variable transmission based on the calculated gear ratio. Its gist is a speed control device for cargo handling vehicles.

The gist of the present invention is to ensure that the vehicle speed does not change even when it is necessary to change the rotation speed of the hydraulic pump for cargo handling in accordance with cargo handling requirements when carrying out cargo handling operations or changing cargo handling operations while driving. It is to do so. In other words, if the rotation speed of the prime mover is changed to the rotation speed required by the cargo handling hydraulic pump, the vehicle speed is determined by the rotation speed of the prime mover and the gear ratio, so if the gear ratio does not change, it will not be related to the amount of travel pedal operation. The vehicle speed will change without any change.

Therefore, the gear ratio of the continuously variable transmission is changed according to the ratio of the rotational speed of the prime mover before and after the cargo handling operation while the vehicle is traveling, thereby controlling the gear ratio in response to the cargo handling operation while the vehicle is traveling. The calculation control of the gear ratio of the continuously variable transmission is performed by setting the gear ratio before cargo handling operation to e, the rotation speed of the prime mover to n,
If the gear ratio after cargo handling operation is E and the rotation speed is N, then
It is necessary to satisfy the relational expression e.n=E.N, where the vehicle speed is constant, and this can be achieved by setting the gear ratio after the operation to E=e.(n/N). As a result, the vehicle speed can be maintained at the vehicle speed before the operation.

Furthermore, by controlling the gear ratio of the transmission basically in accordance with the above relational expression, it has the advantage of compensating for fluctuations in vehicle speed after the cargo handling operation and maintaining the same vehicle speed as before the operation. .

Furthermore, the present invention has the advantage that the gear ratio is automatically controlled when carrying out cargo handling operations while the vehicle is running, thereby eliminating the need for sophisticated operations to keep the vehicle speed constant.

Next, preferred embodiments embodying the present invention will be described below with reference to the drawings.

First Embodiment The first embodiment is an embodiment embodied in a forklift, and FIG. An electric block circuit diagram of a control device that controls the rotation of an engine 4 mounted on a lift and controls the gear ratio of a continuously variable transmission 5 is shown. The engine 4 is used for cargo handling to drive driving wheels 6 via a continuously variable transmission 5, and to supply pressure oil to a cargo handling device, that is, a lift cylinder that moves a fork up and down, and a tail cylinder that tilts a mast in the front and back direction. The hydraulic pump 7 is driven. Further, the opening degree of the throttle that adjusts the rotational speed of the engine 4 is controlled by a throttle actuator 8.

The continuously variable transmission 5 is composed of a variable displacement hydraulic pump 5a and a hydraulic motor 5b.The variable displacement hydraulic pump 5a is driven by the engine 4, and the hydraulic motor 5b is driven by the variable displacement hydraulic pump 5a. It rotates with hydraulic oil supplied by the drive and transmits its rotational force to the drive wheel 6. Variable displacement hydraulic pump 5a
In this embodiment, a swash plate type hydraulic pump is used, and the gear ratio is changed by changing the inclination angle of the swash plate. The angle of inclination of the swash plate that adjusts the gear ratio is appropriately controlled by a swash plate actuator 9.

On the other hand, the travel pedal 1 is provided with a depression angle detector 10 consisting of a potentiometer for detecting the depression angle thereof, and outputs a travel operation amount signal SG1 having a value proportional to the depression angle, that is, the amount of depression. The lift lever 2 is used to drive the lift cylinder, and the lever 2 is provided with a lift lever operation amount detector 11 consisting of a potentiometer that detects the amount of operation of the lift cylinder, and the lift lever operation amount detector 11 is configured to detect a cargo handling operation proportional to the detected amount. A lift operation amount signal SG2 as an amount signal is output.

The tail lever 3 is used to drive the tail cylinder, and the lever 3 is provided with a tail lever operation amount detector 12 consisting of a potentiometer that detects the amount of operation. A tail operation amount signal SG3 is output as a cargo handling operation signal.

The driving function generator 13 to which the driving operation amount signal SG1 is input is a circuit that converts the input operation amount signal SG1 into engine rotation speed data A1 for driving, and converts the input operation amount signal SG1 into a function according to preset driving conditions. Based on the operation amount signal SG1 is the rotation speed data A1
is converted to In this embodiment, the function corresponding to the driving conditions is set to a function in which the throttle opening of the engine 4 linearly increases as the operation amount increases, as shown in FIG. Therefore, according to this function, rotation speed data A1 for travel operation amount signal SG1 is output.

The lift function generator 14 to which the lift operation amount signal SG2 is input is a circuit that converts the input operation amount signal SG2 into engine rotation speed data A2 for driving the lift cylinder, and is a circuit that converts the input operation amount signal SG2 into data A2 of the engine rotation speed for driving the lift cylinder. Manipulated variable signal SG based on the function
2 is converted into rotation speed data A2. As shown in FIG. 1, the function corresponding to the cargo handling conditions was set to a function in which the throttle opening of the engine 4 increases linearly in accordance with an increase in the amount of operation when the fork is raised. Therefore, the rotation speed data A2 for the lift operation amount signal SG2 is output according to this function.

The tailing function generator 15 inputting the tailed manipulated variable signal SG3 receives the input manipulated variable signal SG.
This is a circuit for converting the signal SG3 into engine rotational speed data A3 for driving the tail cylinder, and converts the operation amount signal SG3 into rotational speed data A3 based on a function corresponding to preset cargo handling conditions. In this embodiment, the function corresponding to the cargo handling conditions is such that when the mast is tilted backwards or forwards as shown in FIG. 1, the throttle opening of the engine 4 increases linearly as the amount of operation increases. I set it like this. Therefore, according to this function, rotation speed data A3 for the tilt operation amount signal SG3 is output.

The optimum function for each of the function generators 13 to 15 is selected based on a sensor (not shown) that detects the presence or absence of luggage and its weight, a sensor that detects vehicle speed, and a pressure sensor of a hydraulic circuit that detects the load on the road. Based on this, the running conditions and cargo handling conditions at the time may be determined, and the optimal functions that meet the conditions may be selected.

Each of the rotational speed data A1 to A3 is output to the next stage selection circuit 16. The selection circuit 16 discriminates and selects the data having the largest value among the rotation speed data A1 to A3, and selects the data having the largest value from among the rotation speed data A1 to A3.
It is now output to . Then, when the largest rotational speed data selected by the selection circuit 16 is output to the throttle actuator 8, the actuator 8 adjusts the throttle based on the same data and adjusts the rotational speed of the engine 4 based on the same data. Control.

The rotational speed data A1 outputted from the running function generator 13 and the maximum rotational speed data selected and outputted by the selection circuit 16 are outputted to a comparator 17. The comparator 17 compares both data and determines whether the values are the same, and determines whether the engine 4 is being driven and controlled by the rotation speed data A1 based on the operation of the travel pedal 1, that is, whether the lift lever 2 or the tail lever 3 is operated. This system is used to detect whether cargo handling operations are being carried out. Then, the comparator 17 outputs a signal indicating the presence or absence of a cargo handling operation to an inverse proportion calculator 18 serving as rotation speed ratio calculation means.

The inverse proportion calculator 18 inputs the rotation speed data A1 and a detection signal from a rotation detector 20 that detects the rotation speed N of the engine 4 via a signal converter 19. Then, when the inverse proportion calculator 18 determines that a cargo handling operation is being performed based on the detection signal from the comparator 17, the rotation speed N of the engine 4 at that time (hereinafter referred to as the rotation speed after the operation for convenience of explanation) )
is calculated based on the detection signal from the rotation speed detector 20, and if no cargo handling operation is performed at that time, the rotation speed data for traveling is output based on the operation amount of the travel pedal 1 at that time. The rotational speed n that would have been obtained if the engine 4 had been controlled by A1 (hereinafter referred to as the rotational speed before operation for convenience of explanation) is calculated based on the same data A1. Next, the inverse proportion calculator 18 calculates the rotation speed n, N
A ratio (=n/N) is calculated based on this and is output to a multiplier 22, which will be described later.

Further, when the inverse proportion calculator 18 determines that no cargo handling operation is being performed based on the detection signal from the comparator 17, it always outputs a ratio of 1 to the multiplier 22.

The traveling operation amount signal SG1 is output to the swash plate function generator 21. The swash plate function generator 21 is a circuit that converts the input operation amount signal SG1 into gear ratio data e for controlling the inclination angle (gear ratio) of the swash plate of the variable displacement hydraulic pump 5a,
The operation amount signal SG1 is converted into gear ratio data e based on a preset function corresponding to the driving operation.

As shown in Figure 1, the function corresponding to the driving conditions has a dead band from zero to a small amount of operation, and in a larger range, the engine 4 linearly increases as the amount of operation increases. The throttle opening is set to a function that increases. Therefore, the gear ratio data e for the traveling operation amount signal SG1 is output to the multiplier 22 according to this function.

The multiplier 22 multiplies the gear ratio data e by the ratio (n/N) from the inverse proportional calculator 18, and uses the multiplied value (E=e・(n/N)) as compensation gear ratio data E. It is output to the code converter 23 at the next stage.

The code converter 23 detects the operating position of the forward/reverse lever 24 and performs the compensation shift based on a detection signal SG4 from a detector 25 that detects whether the lever 24 is in forward, reverse, or neutral position. Ratio data E is output to the swash plate actuator 9. Then, in the case of forward movement, the compensation gear ratio data E is set to a negative value in the case of reverse movement, and in the case of neutral, the compensation gear ratio data E is invalidated and the value is set to 0. Output to the swash plate actuator 9.

Then, the swash plate actuator 9 adjusts the inclination angle of the swash plate based on the data E to control the gear ratio.

Next, the effects of the first embodiment configured as described above will be explained.

If you are currently driving by operating only the travel pedal 1, the travel operation amount signal SG is sent from the depression angle detector 10.
1 is output to the running function generator 13. The running function generator 13 converts the running operation amount signal SG1 into running speed data A1 according to the above-mentioned function and outputs it to the selection circuit 16. Selection circuit 16
At this time, based on the fact that only the rotational speed data A1 is input, the data A1 is outputted as the largest value data to the throttle actuator 8, and the rotational speed of the engine 4 is controlled by the same actuator 8. .

The operation amount signal SG1 is supplied to the swash plate function generator 21.
is output to. The swash plate function generator 21 converts the amount of depression of the travel pedal 1 into gear ratio data e according to the above-described function, and outputs the data to the multiplier 22.

On the other hand, since the comparator 17 determines that the data from the selection circuit 16 and the data A1 from the running function generator 13 are the same, the inverse ratio sequence operator 18
outputs a ratio of 1 to the multiplier 22. Therefore, the multiplier 22 outputs the speed ratio data e as it is to the swash plate actuator 9 via the sign converter 23 as compensation speed ratio data E (=e).

At this time, the gear ratio data E is output as is when the vehicle is traveling forward, and is converted to a negative value and output when the vehicle is traveling backwards. Then, the swash plate actuator 9 controls the gear ratio of the continuously variable transmission 5 by adjusting the inclination angle of the swash plate based on this gear ratio data E. Therefore, in this case, the gear ratio is controlled based on the depression of the travel pedal 1. Also, forward/backward lever 24
When is neutral, actuator 9 is set to 0.
Since the compensating gear ratio data E is output, the inclination angle of the swash plate becomes 0.

Next, when the lift lever 2 is operated while driving, the rotation speed data A for driving is performed in the same way as above.
1 is output to the selection circuit 16. On the other hand, the lift lever operation amount detector 11 sends a lift operation amount signal SG.
2 is output to the lift function generator 14. The lift function generator 14 converts the lift operation amount signal SG2 into rotation speed data A2 for driving the lift cylinder according to the above-mentioned function and outputs it to the selection circuit 16.

The selection circuit 16 compares the magnitudes of both rotational speed data A1 and A2, selects the larger one, and outputs it as maximum rotational speed data to the throttle actuator 8, and the actuator 8 controls the rotational speed of the engine 4. .

At this time, since the number of revolutions is required for cargo handling and the torque is required for traveling, the number of revolutions data A2 output from the lift function generator 14 is higher than the number of revolutions of the travel function generator 13. Since the value is set to be larger than the data A1, the data output from the selection circuit 16 becomes the rotation speed data A2. Therefore, in this case, the rotation speed N of the engine 4 is controlled based on the rotation speed data A2. That is, the rotation speed N of the engine 4
is no longer the number of revolutions N based on the amount of depression of the travel pedal 1, but the number of revolutions N increases based on the amount of operation of the lift lever 2. As a result, the vehicle speed increases if the gear ratio remains the same.

On the other hand, since the two data input to the comparator 17 are different, the inverse proportion calculator 18 calculates the number of revolutions n of the engine 4 based on the amount of depression of the travel pedal 1 based on the rotation speed data A1 for travel. At the same time, the rotation speed N of the engine 4 at that time is calculated based on the detection signal from the rotation speed detector 20. Next, the inverse proportion calculator 18 outputs the ratio of the two rotational speeds n and N (=n/N) to the index multiplier 22.

The multiplier 22 multiplies the gear ratio data e based on the amount of depression of the travel pedal 1 by the ratio (=n/N), calculates compensation gear ratio data E (=e・(n/N)), and performs sign conversion. It is output to the swash plate actuator 9 via the device 23.

The swash plate actuator 9 adjusts the inclination angle of the swash plate based on this gear ratio data E, and adjusts the gear ratio of the continuously variable transmission 5 to maintain the vehicle speed at the vehicle speed before the cargo handling operation, that is, the vehicle speed based on the amount of depression of the travel pedal 1. Convert. Therefore, when cargo handling operations are carried out while the vehicle is running, it is possible to compensate for fluctuations in vehicle speed based on cargo handling operations without requiring any sophisticated operating techniques.

Similarly, when the lift lever 2 or the tail lever 3 is operated in a stopped state, or when the tail lever 3 is operated while driving, the optimum rotation speed data A1 to A3 is output from each function generator 13 to 15. The rotation of the engine 4 is controlled under optimal conditions, and the gear ratio of the continuously variable transmission 5 is controlled based on the ratio (=n/N) output from the inverse proportional calculator 18 to maintain the vehicle speed before the cargo handling operation. be done.

Therefore, there is no need for sophisticated operations to keep the vehicle speed constant as in the past.

In this embodiment, the functions of the rotation speed data A1 to A3 and the gear ratio data e to the manipulated variable signals SG1 to SG3 are determined by the function generators 13 to 15, 2, respectively.
Although the number is set to 1 in advance, the number may be further increased or decreased. Of course, it is also possible to set a function corresponding to a certain purpose different from the above and perform the processing based on that function.

Alternatively, the calculation may be performed using a functional formula including various conditions such as running load and cargo handling load.

Furthermore, when the rotation speed data A1 to A3 are input at the same time, the selection circuit 16 selects the largest rotation speed data among them. You may.

In addition, the comparator 17 was provided to calculate and control the gear ratio only when carrying out cargo handling operations while driving, but when the throttle signal and engine speed are almost proportional, such as in an all-speed governor type engine, Can be omitted.

Further, the continuously variable transmission 5 may be of any type as long as its gear ratio can be changed arbitrarily, such as a V-belt type continuously variable transmission.

In addition, the operating amounts of the travel pedal 1, lift lever 2, and tail lever 3 are converted into electrical signals to control the rotation speed of the engine 4, which are mechanically connected to the throttle of the engine 5 via links, wires, etc. It may also be applied to a connected cargo handling vehicle. In this case, it is necessary to provide a pedal angle sensor and a throttle angle sensor.

Further, the code converter 23 does not need to be provided after the multiplier 22, and may be provided, for example, before the swash plate function generator 21 or between the function generator 21 and the multiplier 22. .

Also, instead of the comparator 17, rotation speed data A1, A
2 and cargo handling operation amount signals SG2 and SG3,
The inverse proportion calculator 18 may also be controlled using the detection signal. Further, the depression angle detector 10, the lift lever operation amount detector 11, and the tail lever operation amount detector are not limited to potentiometers, but may be, for example, inductance type displacement meters or variable capacitance type displacement meters. It's okay.

Furthermore, in this embodiment, if the running pedal 1 is replaced with a seesaw-type running pedal 1 operated as shown in FIG. 2, in which front depression is operated to move forward and rear depression is operated to move backward, the code converter 23 is unnecessary. Electronic circuits are simplified. In this case, when the rear depression is performed, the swash plate function generator 21 outputs negative gear ratio data e.

Further, the engine 4 may be replaced with a diesel engine, a gasoline engine, a motor, etc., and in short, any prime mover capable of driving the vehicle and driving the cargo handling hydraulic pump may be used.

Furthermore, although the throttle actuator 8 and the engine 4 are separated in this embodiment,
This may be integrated with the engine, such as an electronically controlled fuel injection device.

Furthermore, it may be applied to various cargo handling vehicles other than forklifts, such as shovel loaders and aerial work vehicles.

Second Embodiment The second embodiment is embodied in a forklift like the first embodiment, but the engine 4 in the first embodiment as the prime mover is replaced with an all-speed governor type diesel engine or a DC motor. The difference is that the engine is equipped with a motor whose rotational speed can be set arbitrarily.

The feature of an all-speed governor type diesel engine is that the load changes at a constant throttle opening, and if the variation in load is smaller than the maximum load, the change in rotational speed is small, so the throttle opening and engine rotational speed are almost proportional. It is in. Therefore, the engine rotation speed N is the rotation speed data A1.
It can be calculated by converting ~A3.

In other words, compensation gear ratio data E(=e・(n/
N)) is E=e・(rotation speed data for driving A
1)/(rotation speed data output from the selection circuit 16).

A second embodiment that utilizes the characteristics of the all-speed governor type diesel engine will be described below with reference to FIG. 3.

That is, in the second embodiment, the comparator 17, signal converter 19, and rotation speed detector 20 provided in the first embodiment are not required, and the inverse proportional calculator 18 uses the rotation speed data A1 for constant running, The largest rotational speed data output from the selection circuit 16 (hereinafter referred to as maximum rotational speed data A) is input, a ratio (=A1/A) is calculated based on both data, and the ratio is output to the multiplier 22. The multiplier 22 calculates compensation gear ratio data E (=e·(A1/A)) in the same manner as in the first embodiment,
The gear ratio of the continuously variable transmission 5 is controlled via the swash plate actuator 9 to compensate for vehicle speed fluctuations.

Therefore, in the second embodiment, the same effects as in the first embodiment can be obtained, and since the comparator 17, signal converter 19, and rotation speed detector 20 are not required, the electronic circuit can be simplified. This is very advantageous in terms of cost and design.

Furthermore, in this embodiment, if the running pedal 1 is replaced with a seesaw-type running pedal 1 operated as shown in FIG. 4, in which front depression is operated as forward running and rear depression is operated as backward running, the code converter 23 becomes unnecessary. Furthermore, the electronic circuit is simplified.

Third Embodiment The third embodiment is an example in which a microcomputer is used.

As shown in Figure 5, each manipulated variable signal SG1~SG
3. Detection signal from rotation speed detector 20 and detection signal from detector 25 provided on forward/reverse lever 24
SG4 outputs to the electronic control unit 31, which is composed of a central processing unit (CPU), a read-only memory (ROM) that stores control programs, and a readable and rewritable memory (RAM) that stores various data. be done. Based on these signals, arithmetic processing operations are executed according to the flowchart shown in FIG.

At this time, a predetermined function is selected based on a program set in advance to calculate the rotation speed data A1 to A3 and the speed ratio data e, and the calculation is performed according to the selected function. Further, calculation of maximum rotational speed data A, engine rotational speed nN, ratio (=n/N), and compensation gear ratio data E, and control of throttle actuator 8 and swash plate actuator 9 are also processed by the program. You may also do so.

In each of the above embodiments, the compensation gear ratio data E was calculated based on the engine speed ratio or the ratio of the engine speed data. However, in the case of a swash plate type variable displacement hydraulic pump and a swash plate type hydraulic motor, Since efficiency decreases as the plate angle becomes smaller, it may no longer be possible to say that the swash plate angle and the gear ratio are proportional.

In that case, the compensation gear ratio based on the engine rotation speed and the compensation gear ratio based on the rotation speed data may be corrected as follows. That is, E=n/(f(θ)・(N-n)+n) E=A1/(f(θ).(A-A1)+A1) Note that f(θ) is the efficiency decrease with respect to the swash plate angle. It is a correction function.

Furthermore, if the swash plate angle usage range of the swash plate used when carrying out cargo handling operations while traveling is limited and the rate of efficiency decline can be approximated by a constant, the calculation may be performed as follows.

E=n/(a・(N-n)+n) E=A1/(a・(A-A1)+A1) Note that a is a correction constant for efficiency reduction.

As described in detail above, according to the above-described embodiments and modified examples, the engine throttle is automatically controlled when cargo handling operations are performed while the vehicle is traveling, so that troublesome engine throttle control during cargo handling operations is avoided. In addition to eliminating the need for any operations, the gear ratio is controlled so that even if the engine speed changes during cargo handling operations, the vehicle speed does not change as long as the driving pedal is held constant, so cargo handling operations do not affect vehicle speed. Further, since traveling can be performed by operating the travel pedal and cargo handling can be performed by the cargo handling operation device, extremely troublesome operations such as inching operations are freed. Furthermore, since the engine speed is increased only when necessary, it is possible to improve noise and fuel efficiency.

[Brief explanation of the drawing]

FIG. 1 is an electric block circuit diagram for explaining a first embodiment of the present invention, FIG. 2 is an electric block circuit diagram for explaining another example of the first embodiment, and FIG. 3 is an electric block circuit diagram for explaining another example of the first embodiment. FIG. 4 is an electric block circuit diagram for explaining another example of the second embodiment, and FIG. 5 is an electric block circuit diagram for explaining the third embodiment of the present invention. electrical block circuit diagram,
FIG. 6 is a flow chart showing the processing operation of the electronic device according to the third embodiment. Travel pedal 1, lift lever 2, tilt lever 3, engine 4, continuously variable transmission 5, variable displacement hydraulic pump 5a, hydraulic motor 5b, throttle actuator 8, swash plate actuator 9, depression angle detector 10, Lift lever operation amount detector 11, tail lever operation amount detector 12, driving function generator 1
3. lift function generator 14, tail function generator 15, selection circuit 16, comparator 17, inverse proportionality calculator 18, rotation speed detector 20, swash plate function generator 21, multiplier 22.

Claims (1)

[Scope of Claims] 1. In a cargo-handling vehicle equipped with a cargo-handling device, in which a prime mover drives a cargo-handling hydraulic pump of the cargo-handling device, and the prime mover travels via a continuously variable transmission, when the vehicle is traveling. a calculation means for calculating a ratio between an amount corresponding to the rotation speed of the prime mover based on the operation amount of the cargo handling operation device and an amount corresponding to the rotation speed of the prime mover before the operation; and a fluctuation in vehicle speed based on the operation of the cargo handling operation device. and a control means for controlling the gear ratio of the continuously variable transmission based on the calculated gear ratio. Travel control device.