JP2005146886A - Tire slip control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tire slip control device capable of suppressing tire slip during a thrusting operation of a work vehicle.
A tire slip control device (18) for determining slip of a tire (3) of a work vehicle (1) based on a rotation speed of an engine (9) and an output rotation speed of a transmission (10) and suppressing the slip of the tire (3). It is provided with detection means for detecting information relating to the work state of the work vehicle 1, and it is determined that the work vehicle 1 is performing a rushing operation based on information relating to the work state of the work vehicle 1 obtained from the detection means. Sometimes it is configured to make the slip determination.
[Selection] Figure 3

Description

  The present invention relates to a tire slip control device for suppressing tire slip of a working vehicle such as a wheel loader.

  A work vehicle such as a wheel loader raises the engine to the maximum rotational speed when the bucket is pushed into the object for excavating and scooping up earth and sand. At this time, if the driving force is larger than the ground contact force, the tire slips. As a result, the tire may be worn or damaged in a short time.

In order to cope with this, the conventional tire slip control device has a tire slip when the engine speed is larger than the vehicle speed (output speed of transmission) and the vehicle speed rapidly increases near 0 km / h. (Hereinafter, referred to as slip determination) to lower the engine speed (see, for example, Patent Document 1).
Japanese Patent No. 3171251 (FIG. 4)

  However, the conventional tire slip control device sometimes suppresses tire slip (decreases the engine rotation speed) even when the work vehicle is not in a rushing operation.

  For example, when the working vehicle climbs a steep slope, the engine rotational speed is increased as compared with the vehicle speed, so that the tire slip may be suppressed by satisfying the above-described slip determination condition. In addition, when the engine speed is high (when the accelerator pedal is depressed) and the brake pedal is depressed suddenly when the foot is released from the brake pedal, the slip judgment condition described above is satisfied and tire slip is suppressed. May end up.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a tire slip control device capable of accurately suppressing tire slip during a thrusting operation of a working vehicle.

  In order to achieve the above object, the present invention device is a tire slip control device that suppresses tire slip by making a tire slip determination of a working vehicle based on an engine rotational speed and an output rotational speed of a transmission, A detecting means for detecting information relating to a work state of the work vehicle, and when it is determined that the work vehicle is in a rushing operation based on information relating to the work state of the work vehicle obtained from the detection means; The slip determination is performed. Thereby, the slip of the tire can be accurately controlled during the driving operation of the working vehicle.

  The detecting means is preferably configured to detect the angle of the hoist arm of the work vehicle and the pressure in the hoist arm cylinder. During the thrusting operation of the work vehicle, the position of the hoist arm of the work vehicle becomes lower and the pressure in the hoist arm cylinder becomes higher than the operation in other work. Therefore, if this characteristic is used, it can be easily determined whether or not the work vehicle is in a rushing operation. Accordingly, tire slip can be accurately suppressed during the rushing operation of the work vehicle.

  The detection means is configured to further detect the displacement of the brake pedal, and when it is determined that the brake pedal is not depressed based on the displacement of the brake pedal obtained from the detection means, from that time You may comprise so that the said slip determination may not be performed until predetermined time passes.

  According to this configuration, it is possible to prevent the slip determination from being made when the work vehicle suddenly removes the foot from the brake pedal from the state where the brake pedal is depressed during the rushing operation. Accordingly, tire slip can be accurately suppressed during the rushing operation of the work vehicle.

  Further, the device of the present invention may be configured to further include a slip control changeover switch for selecting whether or not to control the slip of the tire of the work vehicle. This makes it possible to suppress tire slip when it is necessary to control tire slip, that is, during the rushing operation of the work vehicle.

  ADVANTAGE OF THE INVENTION According to this invention, a slip of a tire can be suppressed during the plunging operation | work of a working vehicle.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a side view of a wheel loader to which a tire slip control device according to an embodiment of the present invention is applied. FIG. 2 is a block diagram showing a schematic configuration of a tire slip control device according to an embodiment of the present invention. FIG. 3 is a flowchart showing the operation of the tire slip control device of FIG. The wheel loader is an example of a working vehicle to which the tire slip control device is applied.

  As shown in FIG. 1, the wheel loader 1 includes a vehicle body 2, and a pair of tires 3 are provided on the lower front side and the lower rear side of the vehicle body 2, respectively. A base end portion of the hoist arm 4 is rotatably attached to the front portion of the vehicle body 2, one end portion of the hoist arm cylinder 5 that moves up and down the hoist arm 4 is attached to the front portion of the vehicle body 2, and the other end portion is the hoist arm. 4 is attached to the base end side. A bucket 6 is rotatably attached to the tip of the hoist arm 4. Further, the bucket 6 is connected via a lever 7 to a bucket cylinder 8 that is rotatably attached to the front portion of the vehicle body 2. The bucket 6 can be rotated by the bucket cylinder 8 as indicated by an arrow R in FIG.

  The vehicle body 2 is equipped with an engine 9 that generates power. A transmission 10 that changes the traveling speed (vehicle speed) of the wheel loader 1 is connected to the engine 9 via a torque converter 11. The transmission 10 is coupled to the tire 3 and transmits power from the engine 9 to the tire 3. Further, the vehicle body 2 is provided with a steering cylinder 12 that changes the traveling direction of the wheel loader 1, thereby steering the vehicle body 2.

  The vehicle body 2 is provided with an operation chamber 13 in which a handle 14 for steering the vehicle body 2, a shift lever 15 for operating the transmission 10, and a work for operating the hoist arm 4 and the bucket 6 as work machines. A machine operation lever 16, a brake pedal 17 for decelerating or stopping the wheel loader 1, and an operation control device (not shown) for controlling the operation of the wheel loader 1 by operating these are provided. The operation control device includes a tire slip control device 18 according to the present embodiment which will be described later.

  The tire slip control device 18 will be described based on the block diagram of FIG. Parts that are the same as the components of the wheel loader shown in FIG.

  As shown in FIG. 2, the tire slip control device 18 suppresses tire slip of the wheel loader 1, and includes a plurality of sensors 19 that detect information related to the traveling state and working state of the wheel loader 1, and these sensors 19. A controller 20 that determines whether or not the tire 3 has slipped based on an output signal from the vehicle (hereinafter referred to as slip determination) and controls an engine control unit (hereinafter referred to as ECU) 21 described later, and this control ECU 21 that controls the rotational speed of the engine 9 by adjusting the fuel injection amount based on the output signal from the container 20. The plurality of sensors 19 and the ECU 21 are electrically connected to the controller 20.

  The plurality of sensors 19 include a brake pedal displacement sensor 22 that detects the displacement of the brake pedal 17, an engine rotation speed sensor 23 that detects the rotation speed of the engine 9, an output rotation speed sensor 24 that detects the output rotation speed of the transmission 10, A hoist arm position sensor 25 for detecting the position of the hoist arm 4 and a hoist arm cylinder pressure sensor 26 for detecting the pressure in the hoist arm cylinder 5 are included. Among these, the engine rotation speed sensor 23 and the output rotation speed sensor 24 are used for slip determination. The brake pedal displacement sensor 22, the hoist arm position sensor 25, and the hoist arm cylinder pressure sensor 26 are used to obtain information regarding the working state of the wheel loader 1.

  The brake pedal displacement sensor 22 is actually arranged so as to detect a brake pressure corresponding to the displacement of the brake pedal 17. Here, the brake pressure is used as a simple representation of the displacement of the brake pedal, but a potentiometer that directly detects the displacement of the brake pedal 17 may be used. The engine rotation speed sensor 23 is arranged to detect the rotation speed of the output shaft of the engine 9. The output rotation speed sensor 24 detects the rotation speed of the output shaft of the transmission 10. The hoist arm position sensor 25 is actually arranged so as to detect the rotation angle of the hoist arm 4 corresponding to the position of the hoist arm 4. The hoist arm cylinder pressure sensor 26 is arranged to detect the pressure in the hoist arm cylinder 5.

  The controller 20 is processed by a control calculation unit 27 that determines slip and controls the ECU 21, and a program (such as a program that suppresses slip) that defines the operation procedure of the control calculation unit 27, or the control calculation unit 27. A storage unit 28 that stores power data and an interface 29 that outputs a result calculated by the control calculation unit 27 to the ECU 21 and receives an output signal from the sensor 19 are provided. Here, the control calculation unit 27 is mainly composed of a microprocessor, and the storage unit 28 is composed of a read-only memory (ROM), a random access memory (RAM) and the like.

  Further, a slip control changeover switch S / C / SW for selecting whether or not to perform the slip control of the wheel loader 1 may be provided between the controller 20 and the ECU 21. This makes it possible to suppress tire slip when it is necessary to control tire slip, that is, during the rushing operation of the work vehicle. The slip control switch S / C / SW may be a logical switch in the controller 20 instead of a physical switch as shown in FIG.

  The tire slip control device 18 configured as described above has the following effects. Based on the information received from the hoist arm position sensor 25 and the hoist arm pressure sensor 26, the controller 20 determines whether or not the wheel loader 1 is in a rushing operation. Specifically, the wheel loader 1 determines that the wheel loader 1 is performing a thrusting operation when the position of the hoist arm 4 is lower than the set position and the pressure in the hoist arm cylinder 5 is higher than the set pressure. . A setting position and a setting pressure for making this determination are set in the storage unit 28 in advance.

  Further, the controller 20 may prevent the slip determination from being performed until a predetermined time has elapsed from the time when it is determined that the brake pedal displacement sensor 22 is at the “position where the brake pedal is not depressed” based on the information received from the brake pedal displacement sensor 22. it can. The brake pressure corresponding to “a position where the brake pedal is not depressed” and a predetermined time (for example, several seconds) are also set in the storage unit 28 in advance. This prevents the wheel loader 1 from judging that the wheel loader 1 has slipped but not slipped, such as when the foot is suddenly released from the state where the brake pedal is depressed during the thrusting operation. Can do.

  Further, as disclosed in, for example, Japanese Patent No. 3171251, the controller 20 determines that a slip has occurred when the increase rate per unit time of the output rotation speed of the transmission 10 exceeds a predetermined value. Alternatively, it is determined that slip has occurred when the rate of increase in the ratio of the output rotational speed to the rotational speed of the engine 9 per unit time exceeds a predetermined value. That is, when the rotational speed of the engine 9 is larger than the vehicle speed (the output rotational speed of the transmission) and the vehicle speed rapidly increases near 0 km / h, it is determined that the tire has slipped. Note that the slip determination method is not particularly limited as long as the slip determination of the tire of the work vehicle is performed based on the engine rotation speed and the output rotation speed of the transmission.

  When it is determined that the tire 3 of the wheel loader 1 is slipping, the controller 20 instructs the ECU 21 to reduce the fuel injection amount to the engine 9 and to reduce the rotational speed of the engine 9. Along with this, the output rotational driving force of the transmission 10, that is, the rotational driving force of the tire 3 also decreases, so that the slip is eliminated.

  The flow of the above operation is shown in FIG. First, it is selected whether or not to perform slip control by the slip control changeover switch (S / C · SW) (step S1). When slip control is not required, it may be turned off.

  If it turns ON in step S1, it will be determined whether the position of the hoist arm 4 is below a setting position (step S2). When it determines with the position of the hoist arm 4 being below a setting position, it is determined whether the pressure in the hoist arm cylinder 5 is more than a setting pressure (step S3). When it is determined that the position of the hoist arm 4 exceeds the set position, it is determined that the wheel loader 1 is not in the thrusting operation, and the slip determination is not performed. When it is determined that the pressure in the hoist arm cylinder 5 is equal to or higher than the set pressure, it is determined whether or not the position of the brake pedal 17 is “a position where the brake pedal is not depressed” (step S4). When it is determined that the pressure in the hoist arm cylinder 5 is lower than the set pressure, it is determined that the wheel loader 1 is not in the rushing operation and the slip determination is not performed. When it is determined that the brake pedal 17 is in the “position where the brake pedal is not depressed”, the slip determination is not performed until a predetermined time has elapsed (step S5). A slip determination is made after a predetermined time has elapsed from the state where the brake pedal 17 is not depressed (step S6). Here, when it determines with having slipped, the rotational speed of the engine 9 is controlled (step S7).

  By repeatedly executing the above steps S1 to S7, slip of the tire 3 of the wheel loader 1 can be suppressed.

  Since the wheel loader 1 hardly steps on the brake pedal 17 during the thrusting operation, steps S4 and S5 among steps S1 to S7 can be omitted. Thereby, the whole apparatus can be simplified. Here, a slip control changeover switch (S / C · SW) is provided, but may be omitted to further simplify the apparatus.

It is a side view of a wheel loader to which a tire slip control device concerning one embodiment of the present invention is applied. It is a block diagram showing a schematic structure of a tire slip control device concerning one embodiment of the present invention. It is a flowchart which shows operation | movement of the tire slip control apparatus of FIG.

Explanation of symbols

1 ... Wheel loader
3 ... tyre
4 ... Hoist arm
5 ... Hoist arm cylinder
9 ... Engine
10 ... Transmission
17 ... Brake pedal
18 ... Tire slip control device
19 ... sensor
20 ... Controller
21 ... Engine control unit (ECU)
22 ... Brake pedal displacement sensor
23. Engine speed sensor
24 ... Output rotation speed sensor
25 ... Hoist arm position sensor
26 ... Hoist arm cylinder pressure sensor

Claims (4)

A tire slip control device that determines tire slip of a working vehicle based on an engine rotational speed and an output rotational speed of a transmission and suppresses tire slip,
A detecting means for detecting information on a working state of the working vehicle;
A tire slip control device configured to make the slip determination when it is determined that the work vehicle is in a rushing operation based on information on the work state of the work vehicle obtained from the detection means.   The tire slip control device according to claim 1, wherein the detection means is configured to detect a position of a hoist arm of a work vehicle and a hydraulic pressure in a hoist arm cylinder. The detection means is configured to further detect the displacement of the brake pedal,
The slip determination is not performed until it is determined that the brake pedal is not depressed based on the displacement of the brake pedal obtained from the detection means until a predetermined time elapses from that time. The tire slip control device described.   The tire slip control device according to any one of claims 1 to 3, further comprising a slip control changeover switch for selecting whether or not to control slip of the tire of the work vehicle.

Images