JP2657797B2 - Automatic transmission for construction machinery - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic transmission for a wheel loader in construction machines.

FIG. 3 is a side view of a wheel loader 1. In the figure, reference numeral 2 denotes a cab, and 3 denotes wheels. FIG. 4 is a diagram of a traveling mechanism system of the wheel loader 1. In the figure, reference numeral 4 denotes an engine, 5 denotes a torque converter, 6 denotes a transmission, 7 denotes a speed stage switching solenoid in the transmission 6, 8 denotes an axle device, and 3 denotes wheels. FIG. 5 is a diagram showing an electric control circuit of a conventional transmission.
In the figure, 9 is a downshift switch mounted on a knob of a boom lever 10, 11 is a transmission control lever for switching between forward and reverse gears and speed gears, 12 and 13 are cam switches, 14 is a power supply, 15 is a controller, 16 , 17,
Numeral 18 is a solenoid.

Next, the electric control of the prior art transmission will be described with reference to FIG. When the transmission control lever 11 is operated in the forward / second speed, an electric circuit is connected to the A → E circuit, and the second speed solenoid 17 is operated to connect a clutch (not shown). When the downshift switch 9 is turned on from this state. A → B → C → F
→ The E circuit is cut. Then, the circuit from A to F is formed by the self-holding function of the controller 15, and the 1st speed solenoid
Activate 16 and engage clutch in 1st gear. Also, when reversing, changing the mission control lever 11 to reverse, the circuit of F → D is cut, and A →
The circuit of F is also cut. At the same time, the circuit from A to F changes from A to E, the second speed solenoid 17 is automatically activated, and the clutch switches from the first speed to the second speed. When the transmission control lever 11 is in the first, third and fourth gear positions, the controller A does not operate because the circuit of A → B → C does not work.

Therefore, as described above, when the transmission control lever 11 is set to the second speed and the downshift switch 9 is turned on during forward excavation, the speed is automatically shifted to the first speed, and the rush force of the wheel loader 1 can be increased. it can.
Then, when the mission control lever 11 is operated backward when the vehicle retreats, the speed is automatically changed from the first speed to the second speed, and the reverse speed is increased. Thus, during excavation work, the work can be performed with the mission control lever 11 kept in the second speed.

Problems to be Solved by the Invention When performing excavation work with a conventional wheel loader, setting the transmission control lever to the second speed and turning on the downshift switch when starting forward excavation automatically shifts to the first speed. However, the thrust of the wheel loader can be increased. When the mission control lever is operated backward when the vehicle retreats, the speed is automatically changed from the first speed to the second speed to increase the reverse speed.
In this prior art transmission, when starting forward excavation, the driver must set the transmission control lever to the second speed and turn on the downshift switch.
Then, after retreating after the excavation operation, when the forward excavation is repeatedly performed, the downshift switch must be turned on again. This operation is troublesome for the driver, and sometimes the driver forgets to operate or performs an erroneous operation. Therefore, the wheel loader and its driver may be damaged or cause a disaster.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-described problems and to provide an automatic transmission capable of causing a controller to detect an excavation operation and shifting forward excavation and reverse traveling to an optimal speed stage.

Means for Solving the Problems Means of the present invention taken to solve the above problems are as follows. An excavation switch for generating a command signal for excavation work is provided near the driver's seat, and a stop switch is provided for the brake device. B. When the excavation switch is turned on, a signal from the excavation switch, a shift lever switching position signal, a signal from a stop switch, and a signal from a vehicle speed detector are set to be input to the controller. When the excavation switch is turned on and the shift lever is switched to the forward position, or when the stop switch is turned on or the shift lever is switched to the reverse position, the above-mentioned controller sets the optimum transmission speed for excavation forward traveling or reverse traveling. Calculate the stage and set the operation signal to be able to be input to the solenoid in the transmission.
Configured.

Action b. When the excavation switch is turned on to perform the excavation operation with the wheel loader and the shift lever is moved to the forward position, the signal is input to the controller, and the controller detects that the excavation operation is performed.

B. Among the traveling mechanisms, for example, a vehicle speed detector is provided in a transmission, and the vehicle speed detector and the controller are connected, so when the vehicle speed falls below a set value,
The transmission speed stage at that time is automatically converted to the next lower speed stage.

C. Since the switch operation position signal of the shift lever is set to be inputtable to the controller, the controller detects the end of the excavation operation by switching the shift lever to the reverse position. Accordingly, the reverse speed is reduced to, for example, the second speed.

D. When loading the soil in the bucket of the wheel loader into a dump truck or the like, the wheel loader is moved forward and close to the down truck. Then, the user depresses the brake to stop the wheel loader, further raises the engine speed to the full, and raises the boom of the wheel loader. In the above case, the brake is depressed, and the stop switch is turned on. Therefore, the ON operation signal of the stop switch is input to the controller. Based on the input signal, a calculation signal from the controller is output to a solenoid in the transmission. Thereby, the transmission returns to the neutral position. Thus, when the ON signal of the stop switch is input to the controller at the time of loading the earth and sand into the dump truck, the wheel loader does not run out of control even if the engine is rotating at a high speed.

E. The wheel loader is automatically shifted by turning the shift lever to the forward or reverse position if the excavation switch is turned on when performing the excavation work because the operation is performed as described in the above paragraphs a to d. . Further, when the brake is depressed and the stop switch is turned on, the transmission automatically returns to the neutral position to prevent the wheel loader from running out of control.

FIG. 1 is a diagram showing an automatic transmission according to the present invention. In the figure, the same reference numerals are given to components using the same components as the conventional technology. 19 is a transmission, 20 to 23 are solenoids in the transmission 19,
24 is an excavation switch, 25 is a shift lever, 26 is a foot-operated brake device, 27 is a stop switch in the foot-operated brake device 26, 28 is a brake pedal, 29 is a vehicle speed detector, and 30 is a controller.

Next, the configuration of the automatic transmission according to the present invention will be described with reference to FIG. An excavation switch 24 for generating a command signal for excavation work is provided near a driver's seat (not shown), and a stop switch 27 is provided for the foot-operated brake device 26. further. The signal from the excavation switch 24, the switching operation signal of the shift lever 25, the signal from the stop switch 27, and the signal from the vehicle speed detector 29 are set so as to be input to the controller 30. When the excavation switch 24 is turned on and the shift lever 25 is switched to the forward position, or when the stop switch 27 is turned on or the shift lever 25 is switched to the reverse position, the controller 30 excavates forward or reverse. The transmission speed stage optimal for traveling is calculated, and the calculation signal is set so that it can be input to the solenoids 20,-, and 30 in the transmission 19.

Next, the function of the automatic transmission according to the present invention will be described. When the excavation switch 24 is turned on and the shift lever 25 is turned to the forward position when performing excavation work with the wheel loader, the signal is input to the controller 30, and the controller 30 detects that the excavation work is performed. I do. Also, for example, transmission 19
The vehicle speed detector 29 is provided in the vehicle, and the vehicle speed detector 29 and the controller 30 are connected to each other. Therefore, when the vehicle speed falls below the set value, the speed stage of the transmission 19 at that time becomes one speed lower. Convert automatically. Further, since the switching operation position signal of the shift lever 25 is set so as to be input to the controller 30, the controller 30 detects that the excavation operation has been completed by switching the shift lever 25 to the reverse position. Therefore, the reverse speed changes to, for example, the second speed. When loading the earth and sand in the bucket of the wheel loader into the dump truck or the like, the wheel loader is moved forward and close to the dump truck. Then, the wheel loader is stopped by depressing the brake pedal 28, and further, the engine rotation is fully increased to raise the boom of the wheel loader. In the above case, the depressing operation of the brake pedal 28 is performed.
Turns on. Therefore, the ON operation signal of the stop switch 27 is input to the controller 30. An operation signal from the controller 30 is output to a solenoid in the transmission 19 based on the input signal. Thereby, the transmission 19 returns to the neutral position. In this manner, when the ON operation signal of the stop switch 27 is input to the controller 30 at the time of loading the earth and sand into the dump truck, the wheel loader does not run away forward even if the engine 4 is rotating at high speed. Absent. A flowchart showing the operation of the controller 30 is shown in FIG.

As described above, in the automatic transmission according to the present invention, if the excavation switch 24 is turned on when performing excavation work, the wheel loader is automatically activated by moving the shift lever 25 to the forward or reverse position. It is shifted.
When the stop switch 27 is turned on by depressing the brake pedal 28, the transmission
19 automatically returns to the neutral position, preventing runaway start of the wheel loader.

Effects of the Invention In the automatic transmission according to the present invention, the excavation switch,
Signals from the shift lever, the stop switch of the brake device, and the vehicle speed detector are set so that they can be input to the controller. Therefore, if the excavation switch is turned on when the construction machine performs the excavation operation, the wheel loader is automatically shifted to the optimal transmission speed stage by moving the shift lever to the forward or reverse position. Further, when the brake is depressed and the stop switch is turned on, the transmission automatically returns to the neutral position to prevent the wheel loader from running out of control.

Therefore, in the construction machine provided with the automatic transmission according to the present invention, the driver is prevented from forgetting to operate or operating erroneously, and the operability, safety and maintenance of the construction machine are improved.

[Brief description of the drawings]

FIG. 1 is a view showing an automatic transmission according to the present invention, and FIG.
Fig. 3 is a flowchart showing the operation of the controller in the automatic transmission according to the present invention. Fig. 3 is a side view of the wheel loader. Fig. 4 is a traveling mechanism system diagram of the wheel loader.
FIG. 1 is a diagram showing an electric control circuit of a conventional transmission. 4 ... Engine 6,19 ... Transmission 7,16-18,20-23 ... Solenoid 15,30 ... Controller 24 ... Excavation switch 25 ... Shift lever 26 ... Brake device 27 ... Stop switch 29 ... … Vehicle speed detector

Claims (1)

(57) [Claims] An excavation switch for generating a command signal for an excavation operation is provided in a construction machine having a transmission capable of electrically controlling a forward-reverse speed and respective speed stages by switching a shift lever. It is provided near the driver's seat, and a stop switch is provided in the brake device, and when the above-mentioned excavation switch is turned on, a signal from the excavation switch, a shift lever switching operation position signal, a signal from the stop switch, a signal from the vehicle speed detector are transmitted. When the input is set to the controller and the excavation switch is turned on, the shift lever is switched to the forward position.When the stop switch is turned on or the shift lever is switched to the reverse position,
An automatic transmission for a construction machine, wherein the controller calculates a transmission speed stage optimal for excavation forward traveling or reverse traveling, and sets the computed signal to be inputtable to a solenoid in the transmission.