JPH04347058A - Discharge capacity control device of working vehicle - Google Patents

Abstract

PURPOSE:To control the accelerting and decelerating speed of a hydraulic motor at an optimum condition by carrying out a fuzzy operation of an optimum discharge capacity control speed depending on the running condition, the load condition, and the data of preference of the operator to the acceleration and the deceleration of the hydraulic motor, and controlling the speed of a hydraulic pump at the optimum value, in a discharge capacity control device of a working vehicle using an HST(Hydro Static Transmission) system. CONSTITUTION:A pressure sensor 52 detects the pressure in a pipeline 42 between a hydraulic pump 31 and a working cylinder 64 as a load pressure, and inputs to a fuzzy control circuit 51. The up and down direction acceleration from an up and down G sensor 53, while the preference of the operator to the vehicle acceleration from a preferred input operation member 54 are input to the fuzzy control circuit 51 respectively. As a result, a fuzzy operation part 51a fuzzy-calculates an optimum discharge capacity control speed based on the input data. The result of the calculation is output to a controller 51b, and the controller 51b controls the discharge capacity control speeds of a variable capacity hydraulic pump 2 and a variable capacity hydraulic motor 4 at the optimum values through electronic control regulators 61 and 62.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to HST (Hydro
The present invention relates to a discharge capacity control device for a work vehicle that employs a static transmission (static transmission) system.

0002

2. Description of the Related Art FIG. 12 shows an example of a hydraulic closed circuit for running a wheel loader employing the above-mentioned HST system. Figure 1
2, when the forward/reverse switching valve 22 is switched to, for example, the F position (forward position) and the travel pedal (not shown) is depressed, the high pressure side pipe line 41 connected to the charge pump 21 is moved to the pump tilt adjustment device 23. The hydraulic chamber 23b is connected to the low pressure side pipe line 42 (connected to the charge pump 21 via the throttle 32). As a result, the piston 23c moves to the left in the figure and the tilting angle (discharge capacity) of the hydraulic pump 2 increases to the forward side, so the hydraulic pump 2 discharges pressure oil to the main pipeline 3a on the forward side. A hydraulic motor 4 connected to the hydraulic pump 2 in a closed circuit is driven by the pressure oil. The rotation is transmitted to the wheels 7 via the transmission 5 and axle 6, and the wheels 7 rotate to move the vehicle forward. The oil discharged from the charge pump 21 is also led as charge oil to the main pipes 3a and 3b via check valves 33a and 33b.

Reference numeral 24 denotes a high pressure selection valve, whose selection pressure always acts on the hydraulic chamber 27b of the motor tilt control device 27. At the beginning of traveling (during acceleration), the pressure in the forward main pipe 3a increases due to the oil discharged from the hydraulic pump 2, so
The high pressure selection valve 24 selects the pressure in the main pipe 3a, and the hydraulic pilot type switching valve 25 changes from the "A" position to the "RO" position.
position or "C" position. Therefore, main pipe 3
The pressure a is also guided to the hydraulic chamber 27a of the tilting control device 27 via the switching valve 25, and as a result, the piston 27c of the displacement control device 27 moves downward in the figure due to the difference in pressure receiving area at both ends, thereby increasing the hydraulic pressure. The discharge capacity of the motor 4 increases.

[0004] When the pressure in the main pipe 3a falls below a predetermined value,
The switching valve 25 is switched to the "A" position, which causes the pipe line 3 to
Since the pressure a is no longer guided to the hydraulic chamber 27a of the displacement control device 27, the piston 27c moves upward and the displacement of the hydraulic motor 4 becomes smaller. Additionally, when the operation of the travel pedal (not shown) is released during forward travel, the hydraulic pump 21
Since the discharge pressure of the hydraulic pump 2 decreases, the differential pressure between the pipes 41 and 42 decreases, and as a result, the piston 23c of the pump tilt adjustment device 23 approaches neutral, and the discharge capacity of the hydraulic pump 2 decreases. When the discharge capacity of the hydraulic pump 2 decreases, brake pressure builds up in the main conduit 3b on the reverse side, and the hydraulic motor 4, that is, the vehicle, decelerates.

Here, 28 and 29 are variable throttles for adjusting the tilt angle control speed (the speed at which the tilt angle changes and corresponds to the discharge volume control speed) of the hydraulic pump 2 and the hydraulic motor 4, respectively. The larger the apertures of the variable apertures 28 and 29, the faster the tilting angle control speed of the hydraulic pump 2 and the hydraulic motor 4 becomes. As the tilt angle control speed increases, the absorption torque of the hydraulic pump 2 and the motor 4 fluctuates faster, and the vehicle can be accelerated or decelerated more quickly, but on the other hand, it lacks smoothness and the riding comfort deteriorates. On the other hand, the smaller the apertures of the variable apertures 28 and 29, the slower the tilt angle control speed becomes. Although it is not possible to do so, it provides smooth acceleration and deceleration and provides a comfortable ride.

[0006]

However, in the above-mentioned conventional device, the apertures of the variable apertures 28 and 29, that is, the tilting control speed is controlled based on, for example, the running condition of the vehicle, the working condition, or the driver's preference (the speed limit). Therefore, the acceleration/deceleration of the hydraulic motor 4, that is, the acceleration/deceleration of the vehicle, could not always be maintained in an optimal state.

SUMMARY OF THE INVENTION An object of the present invention is to provide a discharge capacity control device for a work vehicle that is capable of always maintaining the acceleration/deceleration of a hydraulic motor in an optimal state.

[0008]

[Means for Solving the Problems] To explain in conjunction with FIG. 1 showing one embodiment, the invention of claim 1 includes a variable displacement hydraulic pump 2, and a pair of main pipes 3a, 3 connected to the hydraulic pump 2.
The hydraulic motor 4 is connected in a closed circuit at b, the pump capacity control means 61 controls the discharge capacity of the hydraulic pump 2, and the control speed when controlling the discharge capacity of the hydraulic pump 2 is adjusted by the pump capacity control means 61. The present invention is applied to a discharge volume control device for a working vehicle, which is equipped with a pump speed adjusting means 61 for controlling the pump speed. A driving state detecting means 53 detects the traveling state of the vehicle, a load state detecting means 52 detects the load state of the working machine, and an input means inputs the driver's preference for acceleration/deceleration of the hydraulic motor 4 as a fuzzy variable. 54, a fuzzy calculation means 51a that performs fuzzy calculations according to the outputs of the running state detection means 53, the load state detection means 52, and the input means 54 to determine the optimum discharge volume control speed; Speed control means 5 that controls the pump speed adjustment means 61 so as to reach the optimum value calculated above.
1b, thereby solving the above problem. The invention of claim 3 further provides a variable displacement hydraulic pump 2, a variable displacement hydraulic motor 4 connected to the hydraulic pump 2 in a closed circuit through a pair of main pipes 3a and 3b, and a motor for controlling the discharge displacement of the hydraulic motor 2. The present invention is applied to a displacement control device for a work vehicle, which includes a displacement control means 62 and a motor speed adjustment means 62 that adjusts the control speed when controlling the displacement of the hydraulic motor 4 by the motor displacement control means 62. The above-mentioned running state detection means 53, load state detection means 52, input means 54, and fuzzy calculation means 51a,
A speed control means 51b is provided to control the motor speed adjustment means 62 so that the discharge capacity control speed of the hydraulic motor 2 becomes the calculated optimum value, thereby solving the above problem.

[0009]

[Operation] (1) The fuzzy calculation means 51a of the invention according to claim 1 uses the outputs of the running state detecting means 53, the load state detecting means 52, and the input means 54, that is, the running state of the vehicle, the load state of the work equipment, and the driver's Perform fuzzy calculations according to your preference to find the optimal discharge volume control speed. The speed control means 51b is a pump speed adjustment means 61.
is controlled to control the discharge capacity control speed of the hydraulic pump 2 to the optimum discharge capacity control speed calculated above. (2) The speed control means 51b of the third aspect of the invention controls the motor speed adjustment means 62 to control the discharge capacity control speed of the hydraulic motor 4 to the optimum discharge capacity control speed calculated as described above.

[0010] In the section of means and effects for solving the above-mentioned problems that explains the structure of the present invention, figures of embodiments are used to make the present invention easier to understand. It is not limited to.

[0011]

[Embodiment] An embodiment of the present invention will be explained with reference to FIGS. 1 to 8. Note that parts similar to those in FIG. 12 are denoted by the same reference numerals, and the explanation will focus on the differences. In FIG. 1, oil discharged from a working hydraulic pump 31 driven by an engine 1 is delivered to a pipe 43.
It is guided to a working cylinder 64 via a working switching valve 63, and an unillustrated working device (such as an arm) is driven by expansion and contraction of the working cylinder 64. Reference numeral 52 denotes a pressure sensor that detects the pressure in the work pipe 43, that is, the load pressure of the work machine (hereinafter referred to as front pressure), and the detection result is input to the fuzzy calculation section 51a of the fuzzy control circuit 51. The fuzzy calculation unit 51a also receives outputs from a vertical G sensor 53 that detects acceleration in the vertical direction of the vehicle (hereinafter referred to as pitching acceleration), and a preference input operation member 54 that inputs the driver's preferences regarding acceleration and deceleration of the vehicle. Each is input.

The preference input operation member 54 is slidable in the direction of the arrow, for example, as shown in FIG. 2, and the degree of smoothness and speed is set depending on the slide operation. That is, as the operating member 54 is operated to the left (toward the turtle mark) in the drawing, the smoothness increases and the speed decreases, and when the operating member 54 is operated to the right (towards the rabbit mark), the speed increases and the smoothness decreases. . Smoothness and speediness, which are mutually contradictory elements, correspond to the acceleration/deceleration characteristics shown in Fig. 3. The characteristics shown by the solid line in Fig. 3 are the speediest characteristics, and the characteristics shown by the broken lines are the smoothest characteristics. It shows. The fuzzy calculation section 51
a calculates the optimal tilting angle control speed (optimum discharge volume control speed) by performing fuzzy calculations as described later in accordance with the input preference, the pitching acceleration, and the front pressure.

This optimum tilt angle control speed is input to the control section 51b of the fuzzy control circuit 51. The control unit 51b includes electronic control regulators 61 and 6 that control the tilting angles (discharge capacities) of the hydraulic pump 2 and the hydraulic motor 4, respectively.
2 are connected, and these electronically controlled regulators 61, 6
2 controls the tilt angles of the hydraulic pump 2 and the hydraulic motor 4 in the same manner as the tilt adjustment devices 23 and 27 described in the prior art, depending on whether the vehicle is accelerating or decelerating or traveling at a constant speed. The tilt angle control speed at that time is controlled in accordance with a command from the control section 51b.

FIGS. 4 to 7 show each membership function used in the fuzzy inference in this embodiment. FIG. 4 shows the membership function of the pitching acceleration described above, where A shows the case where the pitching acceleration is large, B shows the case where the pitching acceleration is medium, and C shows the case where the pitching acceleration is small. Further, FIG. 5 shows the membership function of the front pressure, where D indicates the case where the front pressure is low, E indicates the case where the front pressure is intermediate, and F indicates the case where the front pressure is high. Furthermore, Figure 6
is the tilting angle control speed of the hydraulic pump 2 and the hydraulic motor 4 (
G indicates the case of slow, H indicates the case of medium, and I indicates the case of quick. In addition, FIG. 7 shows the operation member 54.
represents the preferred membership function for vehicle acceleration/deceleration inputted by , where J represents smooth and K represents speed.

[0015] Furthermore, it is assumed that the following four rules are used in fuzzy inference. Rule 1-1: If the pitching acceleration is large, set the tilt angle control speed to slow. Rule 1-2: If the pitching acceleration is medium, set the tilt angle control speed to medium. Rule 2-1: If the front pressure is Rule 3-1: If the pressure is high, the tilting angle control speed should be quick. If the pressure is smooth, the tilting angle control speed should be slow. This is based on the fact that the ride is more comfortable if the acceleration/deceleration is slower on a flat road (with a large pitching acceleration), and faster on a flat road (with a small pitching acceleration). Rule 2-1 is based on the fact that workability is better when the acceleration/deceleration speed is faster during heavy work than during light work.

Next, an example of fuzzy inference using the above membership functions and rules will be explained based on FIG. First, the detected value G1 of the pitching acceleration is input from the vertical G sensor 53. If this G1 is included in the range of the large and medium membership functions A and B in FIG. 4, for example, the fitness degrees α1 and α2 corresponding to G1 (FIG. 8( While determining a) and (b)), the above rules 1-1 and 1-2 are applied. That is, first, as shown in FIG. 8(a), rule 1
-1, the membership function A is made to correspond to the membership function G of the tilt angle control speed, and the upper part (indicated by diagonal lines) above the above-mentioned fitness α1 is cut from the membership function G. Similarly, as shown in FIG. 8B, the membership function B is made to correspond to the membership function H according to rule 1-2, and the portion above the fitness level α2 is cut from the membership function H.

Further, when the detected value P1 of the front pressure is inputted from the pressure sensor 52, and this P1 is included in the range of the high membership function F (FIG. 5), for example, the value corresponding to P1 is determined from the membership function F. At the same time, by applying Rule 2-1, the membership function F is made to correspond to the membership function I of the tilt angle control speed, and the upper part of the membership function I is cut off from the above-mentioned fitness β1.

Furthermore, if the preference input using the preference input operation member 54 is, for example, 3 on the smooth side in FIG. As shown in FIG. 8(d), the membership function J is made to correspond to the membership function G of the tilt angle control speed, and the part above the fitness degree γ1 is cut from the membership function G. After that, as shown in FIG. 8(e), the remaining membership functions G, H, I (where G
is the maximum value), calculate the center of gravity, and set this as the optimum tilt angle control speed. The above is an explanation of fuzzy inference.

The optimal tilting angle control speed set above is input to the control section 51b of the control circuit 51, and the control section 51b controls the electronic control regulators 61 and 62 based on this, and controls the hydraulic pump 2 and the hydraulic pressure. The tilting angle of the pump 4 is changed at the optimum discharge capacity control speed.

According to the above control, the tilting angles of the hydraulic pump 2 and the hydraulic pump 4 are finely controlled according to the running condition and working condition of the vehicle, or the driver's preference, so that the hydraulic motor 4, that is, the tilt angle of the hydraulic pump 4 acceleration/deceleration can always be maintained at an optimal state. For example, according to the example in FIG.
The driver's preference is set to "3", which puts a lot of emphasis on smoothness, so the tilt angle control speed is medium despite the high front pressure.

In the configuration of the above embodiment, the electronic control regulator 61 functions as the pump capacity control means and the pump speed adjustment means, and the vertical G sensor 53 functions as the running state detection means.
The pressure sensor 52 constitutes a load state detection means, the preference input operation member 54 constitutes an input means, the fuzzy calculation section 51a constitutes a fuzzy calculation means, and the control section 51b constitutes a speed control means. Further, the electronic control regulator 62 constitutes a motor capacity control means and a motor speed adjustment means.

Further, FIGS. 9 and 10 show another embodiment of fuzzy inference. In this embodiment, as shown in FIG. 9, three membership functions G, H, and I of the tilt angle control speed are used.
In addition to , membership functions G', H', and I' are also used. Here, membership functions G, H, and I are used for pitching acceleration and front pressure membership functions, and membership functions G', H', and I' are used for preferred membership functions. In addition to the above four rules, the following two rules 2-2 and 3-2 are also used. Rule 2-2: If the front pressure is low, make the tilt angle control speed slow. Rule 3-2: If your preference is speed, make the tilt angle control speed quick.

FIG. 10 shows an example of fuzzy inference. First, the detected value G2 of the pitching acceleration is inputted from the vertical G sensor 53 in the same way as described above, and this G1 is determined by, for example, the large and medium membership functions A and B in FIG. If it falls within the range of
The fitness degrees α3 and α4 corresponding to G1 are determined respectively, and the membership functions G,
Cut out H (FIGS. 10(a) and (b)).

[0024] Furthermore, when the detected value P2 of the front pressure is inputted from the pressure sensor 52 and this P2 is included in the low pressure range, for example, the degree of conformity β2 corresponding to P2 is determined and Rule 2-2 is applied. , the membership function D is made to correspond to the membership function G of the tilt angle control speed, and the upper part of the above fitness β2 is cut from the membership function G (Fig. 10(c)
)). In this case, since P2 corresponds to the upper part of the membership function G, no cutting is actually performed.

Furthermore, if the preference input using the preference input operation member 54 is, for example, Speedy 2 in FIG. It is cut at the fitness degree γ2 (Fig. 10(d)). Then, as shown in Fig. 10(e), the remaining membership functions G, H, and I' are logically summed (where G is two), their centroids are determined, and this is optimized. Set as the tilt angle control speed. In this example, since the preference is set to "3" for speedy, the optimum tilting angle control speed is closer to the medium side even though the pitching acceleration is large and the front pressure is low.

In the above description, the electronic control regulator 61
, 62 has been shown. For example, as shown in FIG. The optimum tilting angle control speed may be controlled. Further, the above-mentioned tilt angle control speed control may be performed on either the hydraulic pump 2 or the hydraulic motor 4. Therefore, the present invention can also be applied to a device using a fixed capacity hydraulic motor 4.

[0027]

According to the invention as claimed in claim 1, it is possible to input the driver's preference for acceleration/deceleration of the hydraulic motor as a fuzzy variable, and the driver's preference for acceleration/deceleration of the hydraulic motor can be inputted as a fuzzy variable, and the driver's preference for acceleration/deceleration of the hydraulic motor can be inputted as a fuzzy variable. Since the optimal discharge capacity control speed of the hydraulic pump is controlled by performing fuzzy calculations, the tilting control speed can be precisely controlled according to the vehicle running condition, work condition, and driver's preference, and the hydraulic It becomes possible to always maintain the acceleration/deceleration of the motor in an optimal state. Further, according to the third aspect of the invention, the optimum discharge capacity control speed of the hydraulic motor is controlled by the same control as described above, so that similar effects can be obtained.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram showing an embodiment of a discharge volume control device according to the present invention.

FIG. 2 is a diagram showing the configuration of a preference operation member.

FIG. 3 is a diagram showing acceleration/deceleration characteristics of a vehicle.

FIG. 4 is a diagram showing membership functions of pitching acceleration.

FIG. 5 is a diagram showing a membership function of front pressure.

FIG. 6 is a diagram showing a membership function of tilt angle control speed.

FIG. 7 is a diagram showing membership functions preferred by workers.

FIG. 8 is a diagram showing an example of fuzzy inference.

FIG. 9 is a diagram showing a membership function of tilt angle control speed showing another embodiment.

FIG. 10 is a diagram showing another example of fuzzy inference.

FIG. 11 is a configuration diagram showing another embodiment of the discharge volume control device.

FIG. 12 is a hydraulic circuit diagram illustrating the configuration of a conventional device.

[Explanation of symbols]

1 Engine 2 Variable displacement hydraulic pump 3a, 3b Main pipeline 4 Variable displacement hydraulic motor 31 Hydraulic pump for work 51 Fuzzy control circuit 51a Fuzzy operation section 51b Control section 52 Pressure sensor 53 Vertical G sensor 54 Preference input operation member

Claims (3)

[Claims] Claims: 1. A variable displacement hydraulic pump, a hydraulic motor connected to the hydraulic pump in a closed circuit through a pair of main pipes, a pump displacement control means for controlling the discharge displacement of the hydraulic pump, and the pump displacement control means. A discharge capacity control device for a work vehicle, comprising a pump speed adjusting means for adjusting a control speed when controlling the discharge capacity of a hydraulic pump,
a driving state detecting means for detecting the traveling state of the vehicle; a load state detecting means for detecting the load state of the work equipment; an input means for inputting the driver's preference for acceleration/deceleration of the hydraulic motor as a fuzzy variable; fuzzy calculation means for calculating an optimum discharge volume control speed by performing fuzzy calculations according to the outputs of the state detection means, the load state detection means and the input means; and the discharge volume control speed of the hydraulic pump being the calculated optimum value. A discharge capacity control device for a work vehicle, comprising speed control means for controlling the pump speed adjustment means. 2. The hydraulic motor is of a variable displacement type, a motor displacement control means for controlling the displacement of the hydraulic motor, and a control speed when controlling the displacement of the hydraulic motor by the motor displacement control means. further comprising a motor speed adjusting means for controlling the pump speed adjusting means and the motor speed adjusting means so that the discharge capacity control speed of the hydraulic pump and the hydraulic motor becomes the calculated optimum value. The discharge volume control device for a work vehicle according to claim 1, characterized in that: 3. A variable displacement hydraulic pump, a variable displacement hydraulic motor connected to the hydraulic pump in a closed circuit through a pair of main pipes, a motor displacement control means for controlling the discharge displacement of the hydraulic motor, and a motor displacement control means for controlling the displacement of the hydraulic motor. A discharge capacity control device for a work vehicle includes a motor speed adjusting means for adjusting a control speed when controlling the discharge capacity of a hydraulic motor by a means, a driving state detecting means for detecting a traveling state of the vehicle, and a motor speed adjusting means for adjusting a control speed when controlling the discharge volume of a hydraulic motor. load state detection means for detecting a load state; input means for inputting a driver's preference for acceleration/deceleration of the hydraulic motor as a fuzzy variable; Fuzzy calculation means for performing fuzzy calculation to obtain an optimum discharge capacity control speed; and speed control means for controlling the motor speed adjustment means so that the discharge capacity control speed of the hydraulic motor becomes the calculated optimum value. A discharge volume control device for a work vehicle, characterized in that: