JP3472324B2 - Hydraulic operating device for work vehicle - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic operating device for a working vehicle, such as a traveling crane, for driving a hydraulic actuator such as a hydraulic cylinder or a hydraulic motor. About. 2. Description of the Related Art A working vehicle such as a traveling crane is provided with a hydraulic operating device for driving and operating a hydraulic actuator such as a hydraulic cylinder and a hydraulic motor. Conventionally, this type of hydraulic operating device has a switching valve for controlling the supply of pressurized oil to a hydraulic actuator, and an operating lever for switching the switching valve, and the operating force of the operating lever extends the spool of the switching valve in a longitudinal direction. To supply hydraulic oil to the hydraulic actuator. In a working vehicle such as a traveling crane, the lifting capacity of the crane changes depending on working conditions such as a boom length, a boom angle, and an outrigger extension state. It is necessary to limit the range of the body's turning. For this reason, conventionally, when the revolving range of the revolving body exceeds the safe area, a cylinder that pushes the spool of the switching valve to the neutral position is operated, and the spool of the switching valve is forcibly moved to the neutral position by the piston rod of this cylinder. And the supply of the pressure oil to the hydraulic motor that drives the revolving unit is stopped. However, in such a hydraulic operating device, since the operating force of the cylinder is directly transmitted to the operating lever via the spool of the switching valve, it is difficult for the operator to operate the operating lever. There was a problem of giving a pleasant feeling. The present invention has been made in view of the above problems, and provides a hydraulic operating device for a working vehicle in which the operating force of a cylinder is hardly transmitted to an operating lever via a spool of a switching valve. The purpose is to: SUMMARY OF THE INVENTION In order to solve the above problems, the present invention has a spool and a spool return spring for holding the spool at a neutral position, and controls the supply of pressure oil to a hydraulic actuator. A switching valve for switching the switching valve, an operation lever for switching the switching valve, and a cylinder connected to a spool of the switching valve and returning the spool to a neutral position when an operation amount of the hydraulic actuator exceeds a safe range. In the hydraulic operating device for a working vehicle, a connecting rod is connected to an operation point of the operating lever, and the operating force of the operating lever is connected to the connecting rod via a coil spring having a spring force greater than that of the spool return spring. A spring receiving portion for transmitting to the spool is provided. According to this structure, the operating force of the operating lever is transmitted to the spool of the switching valve via the connecting rod and the coil spring, but the operating force of the cylinder is almost absorbed by the coil spring. Operating force is hardly transmitted to the operation lever. 1 to 3 show an embodiment of the present invention, and FIG. 1 is a schematic configuration diagram of a hydraulic operating device of a working vehicle according to an embodiment of the present invention. In FIG. 1, reference numeral 1 denotes, for example, a turning hydraulic motor of a traveling crane. A switching valve 3 for controlling the supply of hydraulic oil to the hydraulic motor 1 is provided at hydraulic oil supply / discharge ports 1a, 1b of the hydraulic motor 1. They are connected via a hydraulic line 2a and a hydraulic line 2b. This switching valve 3 is shown in FIG.
As shown in the figure, the spool 4 and spool return springs 5a and 5b for holding the spool 4 at the neutral position are provided. When the spool 4 is moved to the left in the figure, the hydraulic oil of the hydraulic motor 1 The pressure oil from the hydraulic pump 7 is supplied to the supply / discharge port 1a, and the hydraulic motor 1 rotates. When the spool 4 of the switching valve 3 is moved rightward in the figure, the switching valve 3 supplies the hydraulic oil from the hydraulic pump 7 to the hydraulic oil supply / discharge port 1b of the hydraulic motor 1 so that the hydraulic motor 1 rotates in the reverse direction. It has become. In FIG. 1, reference numeral 8 denotes the hydraulic motor 1.
The cylinder 8 restricts the amount of operation of the cylinder.
0 is provided. This slit 10 has a spool 4
The connection pin 11 provided at one end of the piston rod 9 is engaged, and when the spool 4 is moved to the left in the drawing, the connection pin 11 moves to the base end side of the piston rod 9. The solenoid valves 13a, 13b are connected to the air supply / discharge ports 8a, 8b of the cylinder 8 via the air pipe 12a and the air pipe 12b.
When the operation amount of the cylinder 8 exceeds the safe range, the solenoid valve 13a (or 13b) is switched to the left position in the figure by a signal from a controller (not shown). The cylinder 8 is connected to the solenoid valve 13a (or 13b) via the air pipe 12a (or 12b).
Compressed air is supplied from an air pump 14, whereby the piston rod 9 of the cylinder 8 expands and contracts, and the spool 4 of the switching valve 3 is forcibly pushed back to the neutral position. An operation lever 1 for switching the switching valve 3
5 is rotatable in the left-right direction in the figure about a shaft 16 as a fulcrum, and a connecting rod 17 is connected to an operation point 15a of the operation lever 15. The connecting rod 17 is provided with a spring receiving portion 18 that transmits the operating force of the operating lever 15 to the spool 4 of the switching valve 3 via the coil spring 19. The spring receiving portion 18 and the coil spring 19 are accommodated in a spring storage box 20 provided at the other end of the spool 4, and the coil spring 19 has a larger spring constant than the spool return springs 5a and 5b of the switching valve 3. A spring having a smaller shrinkage amount for the same load than the spring or the spool return springs 5a and 5b is used. In the drawing, reference numeral 21 denotes a spring receiver. According to such a configuration, the operation of the operation lever is controlled.
Spring force of coil spring 19 for transmitting operation force to spool
(Spring constant) is the spool return spring 5a, 5b of the switching valve 3.
Therefore, the operating force of the operating lever 15 is transmitted to the spool 4 of the switching valve 3 via the connecting rod 17 and the coil spring 19, but the spool 4 of the switching valve 3 is transferred to the cylinder 8.
Operate via spool 4 when returned to more neutral position
The differential force of the cylinder 8 transmitted to the lever 15 is almost absorbed by the coil spring 19 as shown in FIG.
Therefore, the operation amount of the hydraulic actuator (for example, turning
When the swing amount of the body exceeds the safe range, the switching valve 3
When the cylinder 4 is returned to the neutral position by the cylinder 8, the operation of the cylinder 8 transmitted to the operation lever 15 via the spool 4 is performed.
Since the power is attenuated by the coil spring 19, the operator holding the operation lever 15 does not feel discomfort or the like.
The operator recognizes through the operation lever that the amount of operation of the hydraulic actuator has exceeded or approached the safe range.
It is possible to make. [0012] The present invention described above, according to the present invention concatenates the connecting rod acting on the point of the operating lever, this connecting rod,
Since it is provided a spring receiving portion for transmitting the spool returning operation force of the operating lever through the large coil spring of the spring force than the spring of the switching valve to the scan <br/> pool of the switching valve, hydraulic Accession
When the operation amount of the tuator exceeds the safe range, the cylinder
Therefore, even if the spool of the switching valve is returned to the neutral position,
The differential force of the cylinder transmitted to the operating lever via the spool is attenuated by the coil spring, without giving an unpleasant feeling such as the operator is holding the operating lever, hydraulic
The operator can recognize that the operation amount of the actuator has exceeded or approached the safe range through the operation lever.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram showing a schematic configuration of a hydraulic operating device of a working vehicle according to one embodiment of the present invention. FIG. 2 is a diagram showing a configuration of a switching valve of the device. FIG. 3 is a diagram illustrating the operation of the apparatus. [Description of Signs] 1 ... Hydraulic motor 3 ... Switching valve 4 ... Spool 5a, 5b ... Spool return spring 7 ... Hydraulic pump 8 ... Cylinder 15 ... Operation lever 17 ... Connecting rod 18 ... Spring receiving portion 19 ... Coil spring

Claims (1)

(57) [Claim 1] A switching valve having a spool and a spool return spring for holding the spool at a neutral position, and controlling a supply of pressurized oil to a hydraulic actuator. A hydraulic operating device for a working vehicle, comprising: an operating lever for performing a switching operation; and a cylinder connected to a spool of the switching valve and returning the spool to a neutral position when an operation amount of the hydraulic actuator exceeds a safe range. , A connecting rod is connected to an operation point of the operating lever, and a spring receiving portion for transmitting the operating force of the operating lever to the spool via a coil spring having a larger spring force than the spool return spring is provided on the connecting rod. A hydraulic operating device for a working vehicle.