JPH02142971A - Belt-type continuously variable transmission control method - Google Patents

Abstract

PURPOSE:To keep off any worsening of riding quality and controllability by detecting a fact that a farm working machine is proximate to the upper end of an operating range and an operating lever is in upward operation with a sensor, and preventing any reduction gear ratio of the existing belt from occurring. CONSTITUTION:In an interval between a frame 3 and a farm working machine 4, there is provided with a sensor 7 detecting a position of this machine 4 when it goes up to the upmost position. Also, in a base of a machine operating lever 6, there is provided with another sensor 13 contacting at time of upward operation of a bucket 5. When the farm working machine 4 is proximate to the upper end of an operating range and the operating lever 6 is in this upward operation, both these sensors 7, 13 are operated, transmitting the detection signals VS, VL to a controller 14 which outputs the signals as a belt shift control signal after processing them, and controls a belt-type continuously variable transmission 15 so as to make it hold a existing belt reduction ratio. In this connection, when either of these sensors 7, 13 is not operated, normal shift control is performed. Thus, the farm working machine is prevented from any speed change is and around the upper end of the operating range, whereby the worsening of riding quality and controllability is prevented from occurring.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a continuously variable transmission method for a construction vehicle having a working machine, and more particularly to a belt type continuously variable transmission control method.

(Prior Art) Conventional control methods for belt-type continuously variable transmissions, for example, as seen in regular automobiles, change the speed by changing the winding of the belt in response to any load fluctuations such as engine torque and rotation speed. A method is being taken to do so.

(Problem to be Solved by the Invention) However, when the belt speed change is controlled by an external load, the belt changes speed due to the load of the work equipment, which causes problems in riding comfort and operability. This is when an attempt is made to forcibly raise the machine above the upper limit of its operating range, so if it is made to respond to all conditions of the work equipment,
Sensors, judgment processing, etc. are complicated and costs are high.

In view of this, the present invention prevents the belt from decelerating due to the increase in engine load caused by forcing the work equipment to rise above the upper end of its operating range, prevents deterioration of riding comfort and operability, and furthermore, is simple and inexpensive. The purpose of this invention is to provide a belt-type continuously variable speed control method that enables belt speed change control when a work machine is loaded using a sensor or a simple ON-OFF judgment process.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a continuously variable speed control for changing the speed of a belt depending on the magnitude of load such as increase/decrease in engine torque or rotation speed of a construction vehicle having a working machine. Attach sensors such as potentiometers and encoders to the work equipment to detect whether the work equipment has risen to near the upper end of its operating range, and install sensors such as potentiometers and encoders to detect whether the work equipment control lever has been raised. It is attached to the control lever of the machine, inputs the sensor signal of each sensor to the controller, determines whether the sensor signal is near the upper end of the work machine operating range or higher, and if it is determined that the sensor signal is near the upper end of the work machine operating range or higher, the work machine If it is determined that the control lever is being operated to raise the work equipment, the current belt reduction ratio is maintained, and if the determination is otherwise, the control method is to change the speed of the plow belt based on the normal load. Features.

(Example) Hereinafter, an example in which the belt type continuously variable transmission control method according to the present invention is applied to a wheel loader will be described with reference to FIGS. 1 to 5.

Figure 1 shows a side view of the wheel loader.
A frame 3 is provided at the front of a vehicle body 1 having a frame 3, and a working implement 4 having a packet 5 at its tip is provided on the frame 3.

A control lever 6 for the working machine 4 is provided on the seat of the vehicle body 1, and when the control lever 6 is operated, the packet 5 is moved up and down by an angle of θ.

FIG. 2 shows a belt-type continuously variable transmission control system according to the present invention. A sensor 7 is provided between the frame 3 and the working machine 4 to detect the position of the working IR4 when it reaches its highest position.
is provided.

The work i operation lever 6 is attached to the work machine valve 8 and is used when supplying oil from a pump 10 connected to the engine 9 to the work machine cylinder 12 for lifting and lowering the work machine 4 through a pipe line 11. This operation lever 6 is used to raise or lower the packet 5 by switching the valve 8.
A sensor 13 that comes into contact during a lifting operation is provided at the base end of the holder.

The signals from sensors 7 and 13 are then sent to controller 1.
4, and the belt speed change control signal is sent from the controller 14 to the belt type continuously variable transmission 15.

In the figure, 16 is a relief valve, and 17 is a tank.

Therefore, whether the work equipment 4 is near the upper end of the operating range or higher,
The sensors 7 and 13 detect whether or not the work implement operating lever 6 has been operated to raise the work implement. Sensor 7.13 in this case is a limit switch. The detection signal S of the sensor 7 and the detection signal VL of the sensor 13 are sent to the controller 14, and after the signals are processed by the controller 14, a belt speed change control signal is sent to the belt type continuously variable transmission 15.

As shown in FIG. 3, the sensor detection signal {circle around (2)} shows a voltage of VS near the upper end of the operating range of the work implement 4 and above, and shows 0 voltage in other operating ranges.

Further, ■sne, which is smaller than VS, is set as a voltage determination reference value.

As shown in FIG. 4, the sensor detection signal {circle around (2)} indicates a voltage of Vl when the working machine operating lever 6 is operated to raise the working machine, and indicates an O voltage during other operations. Then, VL, which is smaller than VL, is set as the voltage determination reference value.

Next, as shown in FIG. 5, it is determined whether the signal VS input to the controller 14 is greater than or equal to S* or less than or equal to VS
If VS reference VL > VL*, control is performed to maintain the current reduction ratio of (7)/< 0. If VS < VS and VL < VL*, control is performed based on the (normal) load. Controls the belt speed.

This prevents the belt from decelerating due to an increase in engine load due to forcibly raising the working machine above the upper end of its operating range, thereby preventing deterioration of ride comfort and operability.

Although the present invention is applied to a wheel loader as an example of application, it goes without saying that the present invention can also be applied to other construction vehicles equipped with a working machine, such as a motor grader.

(Effects of the Invention) As described above, the present invention prevents the belt from decelerating due to an increase in engine load caused by forcibly raising the work equipment above the upper end of the operating range, improving ride comfort and operability. In addition, it is possible to control the belt speed change when the work machine is loaded by using a low-cost and simple sensor or by a simple ON-OFF judgment process.

[Brief explanation of the drawing]

Figure 1 is a schematic diagram of a wheel loader to which the present invention is applied;
The figure is a schematic explanatory diagram of the belt type continuously variable transmission control system according to the present invention, Figure 3 is a graph showing the relationship between the operating range of the working machine and the sensor output voltage according to Figure 2, and Figure 4 is the same as Figure 2. Work involved I! A graph showing the relationship between the operating lever position and the sensor output voltage, and FIG. 5 is a flowchart of the belt type continuously variable transmission control method according to the present invention. 1...Vehicle body, 3...-Frame, 4...Work equipment, 5
...Packet, 6...Operation lever, 7...Sensor, 8...Work machine valve, 9...Engine, 10...
・Pump 12...Work equipment cylinder, 13...Sensor, 14...-Controller, 15...Belt type continuously variable transmission, VS, VL...Sensor detection signal (voltage), VS*, VL *-・, Voltage judgment standard value.

Claims (1)

[Claims] In continuously variable speed control that changes the speed of a belt depending on the magnitude of load such as an increase or decrease in engine torque or rotation speed of a construction vehicle having a work machine, when the work machine rises to near the upper end of its operating range,
A belt-type continuously variable transmission control method, characterized in that, when a work equipment operating lever is operated upward, speed change of the belt is prohibited and the current speed reduction ratio by the belt is maintained.