JPS61244954A - Speed reduction gear kick-down device in construction machine - Google Patents

Abstract

PURPOSE:To shift down the speed reduction gear to improve the operation ability of a construction machine during working, by connecting a forward movement solenoid in parallel with a series circuit of an accelerator switch, working operation switches and a relay having contacts between a gear shift switch and gear shift solenoids. CONSTITUTION:A series circuit of a kick-off switch 11 which turns on upon depression of an accelerator, a deceleration permission switch 13 which turns on upon operation of a control lever of a working machine, and a relay 4 is connected in parallel with a forward movement solenoid 8. Further, contacts 41, 42 are disposed between first and second solenoids 3, 5 and a gear shift switch 1. In this arrangement, when the working machine control lever is operated to turn on the deceleration permission switch 3, a relay 4 is energized to close the contact 41 so that a second gear stage solenoid is denergized, and therefore, a first stage solenoid is energized to kick down the speed reduction gear. Accordingly, it is possible to automatically increase the power of the construction machine during the working operation of the machine to a value higher than that during running of the machine, so that it is possible to improve the operation ability of the machine thereby it is possible to alleviate the operator's fatigue.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention This invention relates to a transmission kickdown device for a construction machine equipped with an electrically variable transmission.

2. Description of the Related Art When carrying out excavation work using a conventional construction machine, it is common to first set the transmission in 2nd gear and move to the excavation point, then lower the transmission to 1st gear and begin the excavation work. This is to ensure that a large digging force can be obtained during excavation.

Problems to be Solved by the Invention For this reason, the driver must perform variable speed excavation operation and operation and steering of the work equipment at the same time, which causes problems such as early fatigue due to the complicated operation.

This invention was made for the purpose of improving the above-mentioned problems.

Means and operation for solving the problem In construction machinery in which the gear shift switch can electrically control the speed gear of the rainbow transmission, and the forward/reverse switch can electrically control the forward/reverse gear, the forward gear of the gearbox can be electrically controlled. A kick-off switch that is turned on when the accelerator pedal is strongly depressed, a deceleration permitting switch that is turned on when the work equipment control lever is operated, and a series circuit of a relay are connected in parallel to the solenoid, and the contacts of the relay are connected to a speed change switch. A transmission for construction machinery that improves operability during work by interposing it between the 1st gear solenoid and the 2nd gear solenoid, and automatically decelerating from 2nd gear to 1st gear when the relay is turned on. kickdown device.

Embodiment An embodiment of the present invention will be described in detail with reference to the drawings. In the drawings, 1 indicates a speed change switch, and 2 indicates a forward/reverse switch.
The above speed change switch IFi has multiple contacts 1t, 1t*l
The contact 11 is connected to a solenoid 3 provided at the first gear of a transmission mounted on a construction machine (not shown). Contact point 1 again! is connected to the contact piece 4a of the relay 4, and the contact piece 4. is connected to the contact piece 4a of the relay 4. Contact point 41*4 that connects and separates
10,000 and 41 of t is connected to the 1st gear lens 3, and the other 4. is connected to the second speed solenoid 5. The contact 13 of the speed change switch 1 is connected to the third gear solenoid 6, and the contact piece 4α of the speed change switch 1 is connected to the contact 1. When you put it into contact 11, you go to 1st gear, and when you put it into contact 11, you go to 2nd gear.
When the contact is engaged, the transmission can be shifted to 3rd gear.

-The male forward/backward switch 2 has three contacts R and N.

F, the contact R is connected to the reverse solenoid 7, and the contact F is connected to the forward solenoid 8, and when the contact 2α is inserted from the neutral contact N to the contact F, the forward gear is shifted, and the contact is connected to the forward gear. When you shift to R, the transmission shifts to reverse gear.

The forward solenoid 8 includes a kick-down switch 11 that is turned on when the accelerator pedal 10 is strongly depressed, and a work equipment control lever! 2. For example, the deceleration permitting switch 13, which is turned on when the boom operating lever is placed in the raised position, and the series circuit of the relay 4 are connected in parallel, and the contact 4s of the relay 4 forms a self-holding circuit. .

Next, to explain the operation, when the construction machine is running, the work equipment operating lever 12 is in the neutral position and the deceleration permission switch 13 is in the off state as shown in FIG. By operating the forward switch 2, the speed can be changed to any desired speed.

Next, for example, after moving to the working position in 2nd gear, operate the work equipment control lever 12 to the up position, and in this state, press the accelerator pedal 10 strongly, and both the kickdown switch 11 and the deceleration switch 13 will be turned on. Since the relay 4 is energized, the contact piece 4g of the relay 4 becomes the contact 4i side as shown in FIG. 2, and the transmission 1 is automatically decelerated to the first gear. At the same time, relay 4 connects to contact 4. Since the transmission is self-maintained by being turned on, the transmission is maintained at the first gear even if the accelerator pedal 10 is released.

Thereafter, by turning the forward/reverse switch 2 from the forward gear to the neutral or reverse gear, the relay 4 is opened, so that the transmission is automatically returned to the second gear, and travel in the second gear becomes possible.

Note that the deceleration permission switch 13 may be a pressure switch provided in the hydraulic circuit of the boom cylinder.

Effects of the Invention As described in detail above, this invention has the advantage that, for example, when driving in second gear and operating the work equipment operating lever to perform the next work, the transmission is automatically kicked down. There is no need to perform gear shifting operations.

This not only further improves operability during work, but also reduces driver fatigue.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, in which Fig. 1 is a circuit diagram during running, Fig. 2 is a circuit diagram during operation, Fig. 3 is an explanatory diagram of the kickdown switch, and Fig. 4 is an illustration of the deceleration permission switch. It is an explanatory diagram. 1 is a gear change switch, 2 is a forward/reverse switch, 3 is a 1st gear solenoid, 4 is a relay, 4ts41tj. Contact point, 5 is 2nd speed solenoid, 8 is forward solenoid,
10 is the accelerator pedal, 11 is the kickdown switch,
12 is a work equipment operating lever, and 13 is a deceleration permission switch.

Claims (1)

[Claims] In a construction machine in which the speed gear of the transmission can be electrically controlled by the speed change switch 1 and the forward/reverse gear by the forward/reverse switch 2, the forward solenoid 8 of the transmission
A kickoff switch 11 that is turned on when the accelerator pedal 10 is strongly depressed, a deceleration permitting switch 13 that is turned on when the work equipment operating lever 12 is operated, and a series circuit of the relay 4 are connected in parallel, and the relay 4 is connected in parallel. Contacts 4_1 and 4_2 are connected to gear switch 1 and 1st gear solenoid 3.
and 2nd gear solenoid 5, and is configured to shift from 2nd gear to 1st gear when relay 4 is turned on.