JPH08104153A - Speed change device for working vehicle - Google Patents

Abstract

PURPOSE: To provide a speed change controller for a working vehicle which can easily carry out speed change and advance/retreat selecting operation during the excavating or stowing work, without separating the hand from a steering lever and a working machine operating lever. CONSTITUTION: A working vehicle equipped with a steering lever 1 and a working machine operating lever 6 in a driver's room is equipped with an advance/ retreat selecting switches 2, 3 and 4 which are installed on the steering lever 1, momentary type shift-down switch 7, which is forcibly submitted to speed- change from the car speed stage other than the lowest stage of a plurality of advance car speed stages installed on the working machine operating lever 6 and to the lower speed stage, and a control circuit 8 which receives the signals of the advance/retreat selecting switches 2, 3, and 4 and the shift-down switch 7 and outputs the necessary signal to a traveling device.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shift control device for a work vehicle such as a shovel loader, which has a steering lever and a work machine operating lever.

[0002]

2. Description of the Related Art Excavation and loading work of work vehicles such as shovel loaders are carried out by the following operations. That is, when a work vehicle heads for a work object such as loading earth and sand, it starts in forward / second speed in order to obtain a vehicle speed, and shifts down to forward / first speed immediately before plunging into the work object to obtain traction force. Then, the work object is excavated by the work machine. After excavation, to load on a dump truck, etc., perform work such as traveling in reverse / second speed to obtain vehicle speed, and then in forward / second speed. In recent years, as a first conventional technique provided with a lever-type steering operation device in place of a steering wheel for convenience of steering operation during work, Japanese Patent Laid-Open No. 5-501102 shown in FIG. 7 has been proposed. In FIG. 7, a mono-lever type steering lever 40 is provided on the left side of the driver's seat, and a gear shift lever 41 is rotatably attached to an upper portion of the steering lever 40 by a shaft 42. In addition, the steering lever 4
On the back side of 0, a swing switch 43 for performing forward / reverse switching operation is mounted. The gear shift lever 41 can be rotated by the thumb of the left hand, and the operator can select the first, second, third, and fourth speed stages without operating the steering lever 40 and operate the swing switch 43. The vehicle can be switched between forward and reverse.

[0003]

In the above conventional technique, the operator selects the first, second, third, and fourth speed stages without operating the steering lever 40 and operates the swing switch 43. By doing so, the forward / reverse switching operation of the vehicle can be performed, but there are the following problems. Forward ・ Forward immediately before plunging into the work object at 2nd speed, or during that
After shifting to high speed and operating the work machine to excavate the work object, forward / reverse switching and speed change from forward / first speed to reverse / second speed and further forward / second speed / forward It was necessary to switch between forward and reverse to the second speed and load it onto a dump truck or the like. Therefore, there is a problem that the operator must perform operations such as forward / reverse switching, shift operation, and work implement operation at the same time or in a short time, which is complicated and requires skill for the operator.

The present invention has been made in view of the above-mentioned problems, and can easily perform gear shifting and forward / reverse switching operations during excavation and loading work without releasing the steering lever and the working machine operating lever. An object of the present invention is to provide a transmission for a work vehicle capable of performing the above.

[0005]

To achieve the above object, a transmission system for a work vehicle according to the present invention is a work vehicle having a steering lever 1 and a work machine operating lever 6 in a driver's seat. Forcibly shifting from a vehicle speed stage other than the lowest speed stage of the forward vehicle speed stages provided on the working machine operation lever 6 to the speed stages below it The momentary shift down switch 7 of FIG.

The control device 8 in the transmission of the work vehicle constitutes a control circuit which receives signals from the forward / reverse switching switches 2, 3, 4 and the downshift switch 7 and outputs a required signal to the traveling device. A transmission for a work vehicle, characterized in that the switches, relays, and contacts are connected in series between both terminals of a control power supply as described below. (1) Forward changeover switch 2 and first relay F1. (2) The reverse switch 4 and the third relay R1. (3) A contact F1A of the first relay F1 and the third relay R
B contact R1B of No. 1, and 4th relay F2. (4) B contact F1B of the first relay F1 and the third relay R
1 A contact R1A and 5th relay R2. (5) A contact F2A of the fourth relay F2 and the forward solenoid SF. (6) A contact R2A of the fifth relay R2 and the reverse solenoid SR. (7) Sixth relay 2S and predetermined speed stage contacts T2, T0 of the speed change switch. (8) Series connection of the shift down switch 7, the A contact F2A of the fourth relay F2, and the seventh relay SD, and predetermined speed stage contacts T2, T0 of the speed change switch. (9) A contact SDA of seventh relay SD and fourth relay F2
A contact F2A, the seventh relay SD, and predetermined speed stage contacts T2 and T0 of the speed change switch. (10) A contact SDA of the seventh relay SD and the eighth relay Z1. (11) Lower speed stage solenoid S1 of the predetermined speed stage,
A contact Z1A of the eighth relay Z1. (12) The lower speed stage solenoid S1 and the lower speed stage terminal T1 of a predetermined speed stage of the transmission switch. (13) An upper speed stage solenoid S3 of the predetermined speed stage,
The upper speed terminal T3 of the speed change switch. (14) The second speed solenoid S2, the A contact 2SA of the sixth relay 2S, and the B contact Z1B of the eighth relay Z1.

[0007]

With the above-described structure, when excavating the work vehicle, the work vehicle advances at the predetermined forward speed stage and holds the work machine operating lever before the work machine such as a bucket is thrust into the earth and sand.
After operating the shift down switch 7 to shift down to the lower speed stage of the predetermined speed stage to increase the excavation force and excavate,
When earth and sand are loaded on a bucket or the like and switched to a reverse drive, the speed is changed to a predetermined reverse speed and the load can be loaded on another transport vehicle.

The operations of shifting and downshifting during excavation and loading of the work vehicle will be described with reference to the control circuit of the control device 8. When starting excavation and loading work, close the main switch MS and turn the steering lever 1
When the forward speed changeover switch 2 is pressed to set the forward speed mode and the speed change switch 5 is set to a predetermined speed stage, the contact F2A is closed, the sixth relay 2S is excited, the contact 2S is closed, and the second speed solenoid S2 is excited. The mission 10 becomes a forward predetermined speed stage.

When a downshift switch 7 provided on a work implement operating lever 6 such as a bucket is pushed when a work implement such as a bucket of a vehicle plunges into the earth and sand, the seventh relay SD is excited and the contact SDA is closed. Then, the eighth relay Z1 is excited, the contact Z1B is opened, and the predetermined speed stage solenoid S
2 is demagnetized. Therefore, the transmission 10
The forward predetermined speed stage mode is canceled. On the other hand, contact Z1
When A is closed and the lower speed gear solenoid S1 of the predetermined speed gear is excited, the transmission 10 is shifted down to the forward lower speed gear mode. When the shift down switch 7 is released in this state, the contact SDA arranged in parallel with the shift down switch 7 is closed, so the seventh relay S
D is excited and the forward lower speed stage mode is maintained. That is, a self-holding circuit is formed.

When the reverse switch 4 of the steering lever 1 is pressed after the excavation is completed, the transmission 10 enters the reverse mode as described above. Then, the contact F2A of the shift and downshift control circuit is opened, so that the seventh relay SD is demagnetized, the contact SDA is opened and the eighth relay Z1 is demagnetized, the contact Z1A is opened, and the first speed solenoid S1 is demagnetized. Z1B closes. At this time, since the speed change switch 5 remains at the predetermined speed stage position, the predetermined speed stage solenoid S2 is excited and the transmission 10 enters the reverse predetermined speed stage mode. That is, the operator can sequentially perform the operation of the predetermined forward speed step → the lower forward speed step → the reverse predetermined speed step → the predetermined forward speed step without releasing the steering lever 1 and the work machine operation lever 6. In addition, during normal traveling, the speed change switch 5 is set to the lower speed stage T1,
By switching to the predetermined speed stage T2 or the upper speed stage T3,
Solenoid S of each speed stage regardless of forward and backward movement
1 to S3 are excited and the speed can be changed to a required speed.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of a transmission for a work vehicle according to the present invention will be described in detail below with reference to the drawings. 1 is an overall control circuit diagram of a transmission according to an embodiment of the present invention,
In front of the driver's seat, a steering lever 1 provided with a forward changeover switch 2, a neutral changeover switch 3 and a reverse changeover switch 4 on the left side, and a speed change lever switch 5 for performing a speed change operation of 1st speed, 2nd speed and 3rd speed are arranged. Has been done. A working machine operating lever 6 having a momentary downshift switch 7 is disposed on the right side, and each switch is connected to a control device 8.

The transmission 10 includes an input shaft 12 connected to the engine 11, a forward clutch 13, a reverse clutch 14, a first speed clutch 15, a second speed clutch 16, a third speed clutch 17, and an output shaft 18. Forward clutch 13
Is a forward solenoid valve SF, a reverse clutch 14 is a reverse solenoid valve SR, a first speed clutch 15 is a first speed solenoid valve S1, a second speed clutch 16 is a second speed solenoid valve S2, and a third speed clutch 17 is a third speed solenoid valve. The hydraulic circuits (not shown) are connected to S3. The forward solenoid valve SF, the backward solenoid valve SR, the first speed solenoid valve S1, the second speed solenoid valve S2, and the third speed solenoid valve S3 are connected to the control device 8, respectively.

Next, the operation of the above configuration will be described. When the speed change switch 5 is operated, an arbitrarily selected speed change position signal is sent to the first speed solenoid valve S1, the second speed solenoid valve S2 or the third speed solenoid valve S3 via the control device 8 described later with reference to FIGS. Was done 1
Either the high speed clutch 15, the second speed clutch 16 or the third speed clutch 17 is connected and the speed is changed to that speed.
When any one of the forward changeover switch 2, the neutral changeover switch 3 and the reverse changeover switch 4 mounted on the steering lever 1 is pushed, the signal is transmitted to the forward solenoid valve SF or the forward solenoid valve SF via the control device 8 which will be described later with reference to FIGS. It is sent to the reverse solenoid valve SR and either the forward clutch 13 or the reverse clutch 14 is connected to select forward or reverse, or both the forward clutch 13 and the reverse clutch 14 are disengaged to become neutral.

2 to 6 are shift control circuit diagrams incorporated in the control device 8. The main switch MS and the battery constitute a control power supply circuit. Each component is connected in series. (1) Forward push button switch (forward switch) 2
And the first relay F1. (2) Reverse push button switch (reverse switch) 4
And the third relay R1. (3) A contact F1A of the first relay F1 and the third relay R
B contact R1B of No. 1, and 4th relay F2. (4) B contact F1B of the first relay F1 and the third relay R
1 A contact R1A and 5th relay R2. (5) A contact F2A of the fourth relay F2 and the forward solenoid SF. (6) A contact R2A of the fifth relay R2 and the reverse solenoid SR. (7) The sixth relay 2S and the second speed contact of the speed change switch. (8) Series connection of the shift down switch 7, the A contact F2A of the fourth relay F2 and the seventh relay SD, and the second speed contact of the speed change switch. (9) A contact SDA of seventh relay SD and fourth relay F2
A contact F2A, second relay contact of seventh relay SD and speed change switch. (10) A contact SDA of the seventh relay SD and the eighth relay Z1. (11) First speed solenoid S1 and A contact Z1A of the eighth relay Z1. (12) The first speed solenoid S1 and the first speed terminal of the speed change switch. (13) Third speed solenoid S3 and third speed terminal of the speed change switch. (14) The second speed solenoid S2, the A contact 2SA of the sixth relay 2S, and the B contact Z1B of the eighth relay Z1.

In each of the contacts shown in FIGS. 2 and 3, a circle mark indicates a normally open contact point that opens when the corresponding relay is demagnetized and closes when the corresponding relay is excited, and a ● mark indicates that the corresponding relay is demagnetized. It shows a normally closed contact that closes when the corresponding relay is energized. For example, when the first relay F1 is demagnetized, the contact F1A is open and F1B is closed, and when the first relay F1 is excited, the contact F1A is closed and F1B is open. Further, when the fourth relay F2 is demagnetized, the contact F2A is opened and the forward solenoid SF is demagnetized. When the fourth relay F2 is excited, the contact F2A is closed and the forward solenoid SF is excited. .

Next, the operation of switching between forward and backward movement will be described with reference to FIG. Now, when the main switch MS is closed and the forward push button switch (forward change switch) 2 is pushed, the first relay F1 is excited and the contact F1A is closed,
F1B opens. That is, the fourth relay F2 is excited,
The third relay R1 and the fifth relay R2 are demagnetized. Therefore, the contact F2A is closed, the forward solenoid SF is excited, the forward clutch 13 is engaged, and the transmission 1 is transmitted.
0 goes into forward mode. When the reverse push button switch (reverse switch) 4 is pressed, the third relay R1 is excited,
Contact R1A is closed and R1B is open. That is, the fifth relay R2 is excited and the first relay F1 and the fourth relay F2 are demagnetized. Therefore, the contact R2A is closed, the reverse solenoid SR is excited, the reverse clutch 14 is engaged, and the transmission 10 is in the reverse mode.

Next, the operation of shifting and downshifting during excavation and loading work will be described with reference to FIGS. When excavation and loading work is started, the main switch MS is closed, the forward push button switch (forward changeover switch) 2 of the steering lever 1 is pushed to enter the forward mode, and the speed change switch 5 is set to the second speed position. FIG. 4 shows the state, in which the contact F2A is closed, the sixth relay 2S is excited, the contact 2S is closed, the second speed solenoid S2 is excited, and the transmission 10 is in the forward second speed mode.

When the bucket down lever 7 is pushed when the bucket of the vehicle plunges into the earth and sand, the seventh relay SD is excited and the contact SDA is closed, as shown in FIG. Then, the eighth relay Z1 is excited, the contact Z1B is opened, and the second speed solenoid S2 is demagnetized. Therefore, the second forward speed mode of the transmission 10 is released. On the other hand, the contact Z1A is closed, the first speed solenoid S1 is excited, and the transmission 10 is shifted to the forward first speed mode and downshifted. When the shift down switch 7 is released in this state, a current flows through the seventh relay SD because the contact SDA arranged in parallel with the shift down switch 7 is closed, and the first forward speed mode is maintained. That is, a self-holding circuit is formed.

When the reverse push button switch (reverse changeover switch) 4 of the steering lever 1 is pushed after the excavation is completed, the transmission 10 enters the reverse mode in the same manner as described above. Then, as shown in FIG. 6, the contact F2A of the shift and downshift control circuit is opened, so the seventh relay S
D is demagnetized, the contact SDA is opened, the eighth relay Z1 is demagnetized, the contact Z1A is opened, the first speed solenoid S1 is demagnetized, and the contact Z1B is closed. At this time, the shift switch 5
Is in the second speed position, the second speed solenoid S2 is excited and the transmission 10 enters the reverse second speed mode. That is, the operator does not release the steering lever 1 and the work implement operating lever 6 from the second forward speed-the first forward speed.
It is possible to perform operations of second speed-second reverse speed-second forward speed. When traveling normally, change the speed change switch 5 to the first speed, the second speed or the third speed.
When the speed is switched to the desired speed, the solenoids of the respective speed stages are excited regardless of whether the vehicle is moving forward or backward, and the gear can be shifted to a desired speed.

[0020]

As described above in detail, since the present invention is configured as described above, the operator can switch between forward and backward without releasing the steering lever and the working machine operating lever, and from the predetermined forward speed to the lower speed step thereof. Downshift to
The shift operation from the lower forward speed to the predetermined reverse speed can be performed extremely easily. Therefore, excavation of work vehicles,
A shift operation device for a work vehicle can be obtained in which even an unskilled person can easily perform a complicated operation that must be frequently performed during loading.

[Brief description of drawings]

FIG. 1 is an overall control circuit diagram of a transmission according to an embodiment of the present invention.

FIG. 2 is a forward / backward control circuit diagram of the control device according to the embodiment of the present invention.

FIG. 3 is a shift control circuit diagram when the shift switch is in the second speed according to the embodiment of the present invention.

FIG. 4 is a shift control circuit diagram for the second forward speed in FIG.

5 is a shift control circuit diagram when the shift down switch is pushed down to the first forward speed in FIG. 4. FIG.

FIG. 6 is a shift control circuit diagram when switching to reverse in FIG.

FIG. 7 is a diagram showing a conventional technique.

[Explanation of symbols]

1 ... Steering lever, 2 ... Forward push button switch (forward switch), 3 ... Neutral push button switch (neutral switch), 4 ... Reverse push button switch (reverse switch), 5 ... Gear change switch, 6 ... Working machine Operating lever, 7 ... shift down switch, 8 ... control device, 10 ... transmission.

Claims (2)

[Claims] 1. A work vehicle having a steering lever 1 and a working machine operating lever 6 in a driver's seat, and a forward / backward changeover switch 2, 3 provided on the steering lever 1.
4 and a momentary shift down switch 7 for forcibly shifting from a vehicle speed stage other than the lowest speed stage of a plurality of forward vehicle speed stages provided on the working machine operating lever 6 to a speed stage below it. Characteristic work vehicle gearbox. 2. The forward / backward changeover switches 2, 3, 4;
A control circuit 8 that receives a signal from the shift-down switch 7 and outputs a required signal to the traveling device is formed. The above switches, relays, and contacts are connected in series between both terminals of the control power source as described below. A transmission for a work vehicle, comprising: (1) Forward changeover switch 2 and first relay F1. (2) The reverse switch 4 and the third relay R1. (3) A contact F1A of the first relay F1 and the third relay R
B contact R1B of No. 1, and 4th relay F2. (4) B contact F1B of the first relay F1 and the third relay R
1 A contact R1A and 5th relay R2. (5) A contact F2A of the fourth relay F2 and the forward solenoid SF. (6) A contact R2A of the fifth relay R2 and the reverse solenoid SR. (7) Sixth relay 2S and predetermined speed stage contacts T2, T0 of the speed change switch. (8) Series connection of the shift down switch 7, the A contact F2A of the fourth relay F2, and the seventh relay SD, and predetermined speed stage contacts T2, T0 of the speed change switch. (9) A contact SDA of seventh relay SD and fourth relay F2
A contact F2A, the seventh relay SD, and predetermined speed stage contacts T2 and T0 of the speed change switch. (10) A contact SDA of the seventh relay SD and the eighth relay Z1. (11) Lower speed stage solenoid S1 of the predetermined speed stage,
A contact Z1A of the eighth relay Z1. (12) The lower speed stage solenoid S1 and the lower speed stage terminal T1 of a predetermined speed stage of the speed change switch. (13) An upper speed stage solenoid S3 of the predetermined speed stage,
The upper speed terminal T3 of the speed change switch. (14) The second speed solenoid S2, the A contact 2SA of the sixth relay 2S, and the B contact Z1B of the eighth relay Z1.