JPH03237233A - Drive controller for front wheel drive type shovel - Google Patents

Abstract

PURPOSE:To surely prevent the slip of front wheels in simple manner by memorizing the throttle opening degree immediately before the slip of the front wheels when the front wheels slip in the initial period of scooping-up work and opening a throttle up to the memorized opening degree. CONSTITUTION:A throttle lever 12 performs drive control through an actuator 13 by a drive control circuit 17 on the basis of each detection signal of the left and right front wheel revolution speed sensors 5L and 5R, rear wheel revolution speed sensor 10, accelerator pedal stepping-on quantity sensor 7, and a throttle opening degree sensor 14. In this case, if the stepping-on quantity of the accelerator pedal exceeds a prescribed value, and front wheels slip, a throttle is closed to a prescribed opening degree, and then opened again from the prescribed opening degree, and the opening degree up to the slip of the front wheels during the opening of the throttle is memorized. After the slip of the front wheel, the throttle is closed to a prescribed opening degree, and the throttle is opened to the above-described memorized opening degree.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a drive control device for a front wheel drive excavator.
More specifically, the present invention relates to a drive control device that automatically prevents two drive wheels from slipping during scooping work.

(Prior Art) Conventionally, a front wheel drive excavator 51 as shown in FIG.
A hydraulically driven excavator 51A as shown in the figure is provided at the front of the vehicle body, and has a drive mechanism as shown in FIG. 9. That is, the throttle wire 5 is connected to the accelerator pedal 52.
3 is connected to one end of the throttle wire 53.
The other end is connected to a throttle 55 of the engine 54.

With this configuration, when the accelerator pedal 52 is depressed by the driver, the throttle 55 opens in accordance with the amount of depression, and the rotational speed of the engine 54 is increased. The output of the engine 54 is transmitted to a torque converter 56, and a transmission shaft 56A of the torque converter 56 is connected to a differential (differential mechanism) 57. Front wheels 58 and 59 are attached to the left and right ends of the differential 57. Further, the rear wheels 60 in FIG. 8 (the other rear wheel is hidden in the vehicle body) have a steering function.

With the front wheel drive excavator 5■ having the above configuration, when scooping the soil pile 61 as shown in FIG. 10, the front wheel drive excavator 5
When moving the excavator 51A forward and pushing the excavator 51A into the earthen pile 61, if the driving force of the engine 54 exceeds the static friction force of the front wheels 58.59, the front wheels 58.59 slip. When the front wheels 58 and 59 slip, the driver reduces the amount by which the accelerator pedal 52 is depressed to stop the slip, and then tries to press the accelerator pedal 52 deeper again to move the vehicle forward again, or even if the front wheels 58 and 59 slip, the driver does not continue to depress the accelerator pedal 52. There were times when I had to continue working.

(Problems to be Solved by the Invention) In the case of scooping work using the conventional front-wheel drive excavator 51, the driver must perform a depression operation to adjust the amount of depression of the accelerator pedal 52 in order to stop the front wheels from slipping. In many cases, the operator has to move or continue work with the front wheels in slip, resulting in poor operability and premature wear of the front tires 58 and 59.

Therefore, in the present invention, when a slip occurs in the front wheel at the beginning of the work during scooping work, the throttle opening immediately before the slip occurs is memorized, and the throttle opening is automatically adjusted even if the accelerator pedal is depressed. By controlling the opening to the memorized opening limit,
The technical problem to be solved is to prevent the front wheels from slipping.

(Means for Solving the Problem) The technical means for solving the above problem is to replace the drive control device of the front wheel drive excavator with a vehicle speed detection means that detects the vehicle speed and outputs a signal corresponding to the detected speed. , a driving wheel rotation speed detection means that detects the rotation speed of the front wheels and outputs a signal corresponding to the detected rotation speed, and an accelerator pedal depression amount detection means that detects the amount of depression of the accelerator pedal and outputs a signal corresponding to the depression amount. a throttle actuator for opening and closing a throttle of the engine; a throttle opening detecting means for detecting the opening of the throttle and outputting a signal corresponding to the detected opening; and a signal from the accelerator pedal depression amount detecting means. When it is recognized that the amount of depression of the accelerator pedal exceeds a predetermined value, it is determined that the front wheels have slipped based on the signal from the vehicle speed detection means and the signal from the drive wheel rotation speed detection means. In this case, the throttle actuator is controlled to close the throttle to a predetermined opening while referring to the signal from the throttle opening detection means, and then the throttle actuator is controlled to open the throttle from the predetermined opening. At the same time, in the process of opening the throttle, the throttle opening until the front wheel slips is memorized, and after the slip, the throttle is controlled to be closed again to a predetermined opening, and then the front wheel is and drive control means for controlling the throttle actuator to open the throttle to the throttle opening degree immediately before the previous slip.

(Function) According to the drive control device for a front-wheel drive excavator having the above configuration, the drive control means for controlling the throttle actuator inputs the signal from the accelerator pedal depression amount detection means so that the depression amount of the accelerator pedal reaches a predetermined value. When it is determined that the front wheels have slipped based on the signal from the vehicle speed detection means and the signal from the driving wheel rotation speed detection means, the throttle opening detection means The throttle actuator is controlled to close the throttle to a predetermined opening while referring to a signal from the controller, and then the throttle actuator is controlled to open the throttle from the predetermined opening, and the throttle is opened. During this process, the throttle opening until the front wheel slips is memorized, and after the slip, the throttle is controlled to be closed again to a predetermined opening, and then the throttle opening is closed to the throttle opening just before the previous slip of the front wheel. By controlling the throttle actuator to open the throttle, the front wheels are automatically prevented from slipping without the driver having to manually adjust the amount of depression of the accelerator pedal.

(Example) Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a perspective external view of a differential mechanism l installed in a front-wheel-drive excavator similar to the conventional front-wheel-drive excavator 51. As shown in this drawing, a left front wheel 2 and a right front wheel 3 are attached to the left and right sides of the differential mechanism l, and a differential housing 4 is equipped with an electric current that detects the rotation of the left front wheel 2 and generates an electric current corresponding to the rotation speed. A rotation speed sensor 5L that outputs a signal and a rotation speed sensor 5R that detects the rotation of the right front wheel 3 and outputs an electric signal corresponding to the rotation speed are attached.

Incidentally, the input shaft lA of the differential mechanism 1 is connected to the output section of a torque converter 15, which will be described later, as in the conventional front-wheel drive excavator 51.

FIG. 2 is a perspective view showing the part of the accelerator pedal 6 installed in the front-wheel drive excavator. An accelerator pedal depression amount sensor 7 is attached that outputs an electric signal corresponding to.

In addition, FIG. 3 shows a rear wheel 9 (one of the two wheels is shown) supported by a rear axle beam 8 of a front-wheel drive excavator.
This shows the part. A rear wheel rotation speed sensor 10 is disposed near the rear wheel 9 to detect the rotation of the rear wheel 9 and output an electric signal corresponding to the rotation speed. Note that this rear wheel 9 is used for steering and is not driven.

Therefore, when the front wheel drive excavator moves forward or backward, the rear wheels 9 rotate at a rotational speed corresponding to the vehicle speed, so the rotational speed of the rear wheels 9 has a value corresponding to the vehicle speed.

FIG. 4 shows the engine 11 of the front-wheel drive excavator in terms of the road surface.
A throttle lever 12 connected to the first throttle is provided, and the throttle lever 12 is connected to a plunger 13A of the actuator 13 so as to be rotated by an actuator 13 formed by a step motor or the like. Further, a throttle opening sensor 14 is attached to the throttle lever 12. The throttle opening sensor 14 detects the rotation angle of the throttle lever 12 and outputs an electric signal corresponding to the rotation angle, that is, the throttle opening of the engine 11. . Additionally, a torque converter 15 is provided adjacent to the engine 11.
is equipped.

FIG. 5 shows a control block diagram of a drive control device for a front-wheel drive excavator.

As shown in FIG. 5, the actuator 13, which rotates the throttle lever 12 to open and close the throttle of the engine 11, is driven and controlled by a drive control circuit 17 using a microcomputer. This drive control circuit 17
includes a rotation speed sensor 5L that detects the rotation of the left front wheel 2 and outputs an electric signal corresponding to the rotation speed, and a right front wheel 3.
a rotation speed sensor 5R that detects the rotation of the rear wheel 9 and outputs an electric signal corresponding to the rotation speed; and a rear wheel rotation speed sensor 10 that detects the rotation of the rear wheel 9 and outputs an electric signal corresponding to the rotation speed. , the accelerator pedal depression amount sensor 7 and the throttle opening sensor 14 are connected, and signals output from each sensor are input. Then, the drive control circuit 17 drives the actuator 13 according to the flowchart shown in FIG.
By controlling the opening and closing of the throttle, it is possible to perform scooping operations using a front-wheel drive excavator with less slippage of the front wheels.

Next, the drive control circuit 1
The control of No. 7 will be explained.

In step S1 of the flowchart, it is determined whether the rear wheels (RR) 9 of the front-wheel drive excavator are rotating, and if it is determined that the front-wheel drive excavator is moving forward, the accelerator pedal 6 is depressed in step S2. It is determined whether or not the amount of depression of the accelerator pedal 6 is greater than a predetermined value A.
When it is determined that the amount of depression is larger than the predetermined value A, in step s3, a value obtained by multiplying the rotation speed of the larger of the rotation speeds of the front wheels (FR) 2 and 3 and the rotation speed of the rear wheel 9 by a constant K is determined. If the number of rotations on the front wheel side is large, it is determined that the front wheel is slipping. In this case, during scooping work, the excavator crashes into the earth, for example, and the vehicle speed, that is, the rotation of the rear wheels 9, decreases rapidly, while the front wheels 2
．． The rotation of the front wheel 3 will drop for a while, but the driving force will decrease at a certain point.
．． This shows that if the static friction force of 3 is exceeded, the front wheels 2.3 will slip.

If it is determined in step S3 that the front wheels 2.3 are slipping, the actuator 13 is controlled in step S4 so that the throttle is closed to the idle position. Then, as shown in step S5, the throttle opening degree C is set to O (idle opening degree). In step S6, the actuator 13 is controlled to increase the throttle opening degree C by a certain amount. In step S7,
It is determined whether the front wheels 2.3 are slipping or not, and if it is determined that they are not slipping yet, step S8
, change the throttle opening C to a new value E= (C+D
). On the other hand, if it is determined that the front wheels 2.3 are slipping as a result of the determination in step S7, the actuator 13 is controlled in step S9 so that the throttle is closed to the idle position. Thereafter, in step S10, the front wheels 2 and 3 are
The actuator 13 is controlled so that the throttle is opened to the throttle opening just before the throttle opening was determined to be slipping. - Then, in step Sll, it is determined whether the accelerator pedal 6 has been returned to the idle position, and if it is determined that it is still being depressed, the process returns to step S3, while the accelerator pedal 6 is returned to the idle position. If it is determined that it has been returned, the process returns to step Sl.

Note that in step 811, when the accelerator pedal 6 is returned to the idle position, when the brake pedal is depressed, or when the parking brake is activated, the process returns to step SL.

Fig. 7 is a timing chart showing the control according to the above flowchart, in which Fig. 7 (A) shows the accelerator pedal depression amount, Fig. 7 (B) shows the throttle opening, and Fig. 7 (C) shows the rearward depression amount. The rotation speed of wheel 9, Figure 7 (D) is the rotation speed of front wheel 2 or 3, and Figure 7 (E) is the engine 11 for reference.
, and each of the above is shown corresponding to the steps in the flowchart of FIG.

As described above, during scooping work with a front-wheel-drive excavator, the drive control circuit 17 controls the actuator 13, so that even if the front wheels 2.3 temporarily slip at the beginning of the work, the throttle of the engine 11 remains unchanged. Because the opening is automatically controlled to the point just before front wheels 2 and 3 slip,
Even if the accelerator pedal 6 is continued to be depressed, the front wheels 2 and 3 are prevented from slipping thereafter.

(Effect of the invention) As described above, according to the present invention, in the scooping operation,
If the accelerator pedal is depressed beyond a predetermined amount, even if the front wheels of a front-wheel-drive excavator slip temporarily at the beginning of the work, the throttle opening will automatically resume at the throttle opening just before the front wheels slipped. Since the engine is driven, the driver can continue scooping work without having to adjust the accelerator pedal depression to prevent the front wheels from slipping. Furthermore, since the occurrence of slip in the front wheels can be reduced, the life of the front tires can be extended.

[Brief explanation of drawings]

1 to 7 relate to one embodiment of the present invention, FIG. 1 is a perspective external view showing the front wheel portion and the arrangement state of the rotation speed sensor that detects the rotation speed of the front wheel, and FIG. The installation state of the accelerator pedal depression amount sensor is shown in Figure 3. Figure 3 is a perspective external view showing the arrangement state of the rotation speed sensor that detects the rotation speed of the rear wheel.
Fig. 4 is a road body mechanism diagram for controlling opening and closing of the engine throttle, Fig. 5 is a control block diagram, Fig. 6 is a control flowchart of the drive control circuit, Figs. 7 (A), (B),
(C), (D), and (E) are timing charts showing the effects of the embodiment. Furthermore, Fig. 8 is a diagram of a conventional front-wheel drive excavator, Fig. 9 is a road drive mechanism diagram of a conventional front-wheel drive excavator, and Fig. 1O is a side view showing the state of scooping work with a front-wheel drive excavator. be. 2.3: Front wheel 5L, 5R: Front wheel rotation speed sensor 6 Near = 9 = 0 1 2 3 4 7 l Accelerator pedal Accelerator pedal depression amount sensor Rear wheel: Rear wheel rotation speed sensor: Engine throttle lever: Actuator: Throttle opening degree Sensor: Drive control circuit-811: Steps of flowchart

Claims (1)

[Claims] A vehicle speed detection means detects the vehicle speed and outputs a signal corresponding to the detected speed, a drive wheel rotation speed detection means detects the rotation speed of the front wheels and outputs a signal corresponding to the detected rotation speed, and an accelerator pedal an accelerator pedal depression amount detection means for detecting a depression amount and outputting a signal corresponding to the depression amount; a throttle actuator for opening and closing an engine throttle;
Throttle opening detection means detects the opening of the throttle and outputs a signal corresponding to the detected opening, and signals from the accelerator pedal depression amount detection means are input so that the depression amount of the accelerator pedal reaches a predetermined value. When it is determined that the front wheels have slipped based on the signal from the vehicle speed detection means and the signal from the drive wheel rotation speed detection means, the throttle opening detection means A process in which the throttle actuator is controlled so that the throttle is closed to a predetermined opening degree while referring to a signal from the above, and then the throttle actuator is controlled to open the throttle from that predetermined opening degree, and the throttle is opened. The throttle opening until the front wheel slips is memorized, and after the slip, the throttle is controlled to be closed again to a predetermined opening, and then the throttle is closed to the throttle opening just before the previous slip of the front wheel. and drive control means for controlling the throttle actuator to open the throttle actuator.