JPH0522654U - Hydraulic circuit of small shovel - Google Patents

Abstract

(57) [Abstract] [Purpose] In the conventional small-sized shovel, the turning parking brake is released and the brake is operated by operating the switch. In addition, water such as muddy water entered the electric circuit for the swing parking brake and rusted switches and solenoids. It is an object of the present invention to solve the problems that the switch operation of the swing parking brake is troublesome and the electric circuit has poor maintainability. [Structure] The turning switching valve in the hydraulic circuit of the small excavator is provided with a sub-valve that performs switching operation in conjunction with the turning switching valve, and the cylinder of the turning parking mechanical brake device and the brake circuit pressure reducing valve are provided. A brake pilot switching valve is provided in the communicating pipe line, and when the turning switching valve is operated, the turning parking brake of the mechanical brake device is automatically released.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a hydraulic circuit for a swing parking brake of a small excavator.

[0002]

[Prior Art]

 FIG. 2 is a side view of the small shovel. In the figure, 1 is a lower traveling body of a small shovel, 2L and 2R are left and right traveling motors, 3 is an upper revolving body, 5 is a revolving motor, 6 is a work attachment mounted on the front portion of the upper revolving body 3, and 7 is The work attachment 6 is a boom, 8 is an arm, 9 is a bucket, 10 is a boom cylinder, 11 is an arm cylinder, 12 is a bucket cylinder, 13 is a dozer device, and 14 is a dozer cylinder of the dozer device 13.

FIG. 3 is a prior art circuit diagram of a small excavator. In the figure, 15 is a mechanical brake device for turning parking of the turning motor 5, 16 is a brake cylinder which is a cylinder of the mechanical braking device 15, 17 and 18 are overload relief valves, 19 is a turning speed reducer, and 20 is a A control valve having a multi-valve structure, 21 is a direct push-pull operation type swivel switching valve disposed in the control valve 20, and 22, ..., 26 are other actuators (for convenience of explanation, in FIG. Control valves for controlling the actuator (not shown), 27 and 28 for the first and second hydraulic pumps, 29 for an oil tank, 30 for a pressure reducing valve, and 31 for a brake circuit pressure reducing valve in the pressure reducing valve 30. , 32 is a main circuit pressure reducing valve, 33 is a brake solenoid switching valve, 34 is a solenoid of the solenoid switching valve 33, 35 is an electric circuit, and 36 is an electric circuit. In the 35 switch, 37 is a power supply.

Next, a conventional circuit will be described with reference to FIGS. 2 and 3. In the circuit of the conventional technology of a small excavator, various hydraulic actuators are divided into two groups A and B, and are driven by the first hydraulic pump 27 and the second hydraulic pump 28, respectively. Discharge of the hydraulic pump (first hydraulic pump 27) that drives the group (for example, group A as shown in FIG. 3) in which the swivel switching valve 21 is arranged in one of the groups and the swivel switching valve 21 is arranged. The brake pressure reducing valve 31 is provided on the side, and when the small shovel turns, the pressure oil derived from the brake pressure reducing valve 31 is applied to the mechanical brake device 15 for turning parking to release the turning parking brake. I have to.

When the small excavator stops the engine, the first hydraulic pump 27 and the second hydraulic pump also stop rotating. Therefore, since hydraulic pressure does not act on the brake cylinder 16, the mechanical brake device 15 performs the turning parking brake by the spring force of the built-in spring a provided for the brake cylinder 16. Next, when the switch 36 is turned off with the engine started, the solenoid 34 is not energized. Since the brake electromagnetic switching valve 33 is at the tank communication oil passage position B, pressure oil does not act on the brake cylinder 16. Therefore, also in this state, the mechanical brake device 15 is performing the turning parking brake. However, when the small shovel turns, the switch 36 is first turned on. Since the solenoid 34 is energized, the electromagnetic switching valve 33 is switched from the tank communication oil passage position B to the opening oil passage position C. The pressure oil from the first hydraulic pump 27 passes through the pipeline 38, the brake circuit pressure reducing valve 31 in the pressure reducing valve 30, the pipeline 39, the position of the electromagnetic switching valve 33, the pipeline 40, and the brake cylinder 16. Is sent to the rod side oil chamber. Since the brake cylinder 16 is contracted against the spring force of the built-in spring B, the swing parking brake of the mechanical brake device 15 is released. As a result, the small excavator can turn without hindrance.

[0006]

[Problems to be solved by the device]

 When the small shovel turned, it was necessary to release the turning parking brake by operating the switch and also to operate the switch when the brake was activated. The effort was troublesome, and sometimes I inadvertently forgot to operate the switch. In addition, the switches in the electric circuit for the swing parking brake may rust and cause malfunction, which is a maintenance problem. An object of the present invention is to provide a hydraulic circuit that does not require an electric circuit for a swing parking brake and can automatically activate and release the swing parking brake.

[0007]

[Means for Solving the Problems]

 According to the present invention, the swivel switching valve is provided with a sub-valve that performs switching operation in conjunction with the swivel switching valve.When the swivel switching valve is in the neutral position, the sub valve is in the shutoff oil passage position, and When the switch position is set, the sub valve is set to switch to the open oil passage position, and the brake pilot changeover valve is installed in the pipe line that connects the cylinder of the mechanical brake device for swing parking and the pressure reducing valve for the brake circuit. However, the pilot pressure receiving part of the brake pilot switching valve is connected to the sub valve via a pipe line, and the pressure discharged from the brake circuit pressure reducing valve to the pipe line leading to the brake pilot switching valve. A part of the oil was passed through the sub-valve to be constructed.

[0008]

【Example】

 FIG. 1 is a hydraulic circuit diagram of the present invention. In the figure, the same reference numerals are given to those using the same constituent elements as those in the prior art. Reference numeral 41 is a swing switching valve, 42 is a sub valve of the swing switching valve 41, 43 is a brake pilot switching valve, and 44 is a pilot pressure receiving portion of a brake pilot switching valve 43 (hereinafter referred to as brake valve 43).

Next, the configuration of the hydraulic circuit of the present invention will be described with reference to FIG. The swivel switching valve 41 is provided with a sub-valve 42 that performs switching operation in conjunction with the swivel switching valve 41. Is set to switch to the open oil passage position when the switch valve is in the switch position, and the brake valve 43 is connected to the pipeline that connects the brake cylinder 16 of the mechanical brake device 15 for turning parking and the brake circuit pressure reducing valve 31. The pilot pressure receiving portion 44 of the brake valve 43 and the sub-valve 42 are communicated with each other via a conduit 45, and are led out from the brake circuit pressure reducing valve 31 to a conduit 46 leading to the brake valve 43. A part of the pressure oil is passed through the sub-valve.

When the small shovel stops the engine, the first hydraulic pump 27 and the second hydraulic pump also stop rotating. Therefore, since the hydraulic pressure does not act on the brake cylinder 16, in this case, the mechanical brake device 15 performs the turning parking brake like the prior art. Next, when the engine is started and the vehicle is not turning, that is, when the turning switching valve 41 is in the neutral position, the sub valve 42 is in the cutoff oil passage position. No pressure oil acts on the. Since the brake valve 43 is located at the tank communication oil passage position D, pressure oil does not act on the brake cylinder 16. Therefore, even in this state, the mechanical brake device 15 applies the turning parking brake. However, when turning the small shovel, the turning switching valve 41 is switched from the neutral position. The sub-valve 42 is switched to the open oil passage position in conjunction with the switching operation of the turning switching valve 41. A part of the pressure oil from the first hydraulic pump 27 branches from the pipe line 46, and acts on the pilot pressure receiving portion 44 via the pipe line 47, the opening oil passage position of the sub valve 42, and the pipe line 45. The brake valve 43 is switched from the tank communication oil passage position D to the opening oil passage position E. The pressure oil from the first hydraulic pump 27 is branched in the pressure reducing valve 30, one of which passes through the switching positions of the main circuit pressure reducing valve 32 and the swing switching valve 41, and is supplied to the swing motor 5, and the other one. Oil is fed to the rod-side oil chamber of the brake cylinder 16 through the brake circuit pressure reducing valve 31, the pipe line 46, the E position of the brake valve 43, and the pipe line 40 '. Since the brake cylinder 16 is contracted against the spring force of the built-in spring B, the swing parking brake of the mechanical brake device 15 is released. As described above, the swing parking brake of the small excavator can be automatically activated and released.

[0011]

[Effect of the device]

 As described above, according to the present invention, the swing switching valve in the hydraulic circuit equipped in the small shovel is provided with the sub-valve that is switched in conjunction with the swing switching valve, and when the swing switching valve is in the neutral position, the sub valve is operated. Is set to the shutoff oil passage position, and the sub-valve is switched to the opening oil passage position when the turning switching valve is in the switching position.The cylinder of the mechanical brake device for rotary parking and the pressure reducing valve for the brake circuit are set. A brake pilot switching valve is provided in the communicating pipeline, and the pilot pressure receiving section of the brake pilot switching valve and the sub-valve are communicated via the pipeline, and the brake circuit pressure reducing valve is used for the brake pilot. A part of the pressure oil led to the conduit leading to the switching valve was made to pass through the sub-valve. As a result, the electric circuit (including the switch) for the turning parking brake, which is equipped in the small-sized excavator of the related art, is unnecessary, and the turning parking brake can be automatically activated and released. Therefore, the small excavator equipped with the hydraulic circuit of the present invention improves the turning operability and maintainability.

[Brief description of drawings]

FIG. 1 is a hydraulic circuit diagram of a small excavator according to the present invention.

FIG. 2 is a side view of a small excavator.

FIG. 3 is a conventional hydraulic circuit diagram.

[Explanation of symbols]

 5 Swing Motor 15 Mechanical Brake Device 16 Brake Cylinder 21,41 Swing Changeover Valve 27,28 First and Second Hydraulic Pumps 31 Brake Circuit Pressure Reducing Valve 42 Sub-valve 43 Brake Pilot Changeover Valve

Claims (1)

[Scope of utility model registration request] 1. A hydraulic excavator mounted on a small excavator is divided into two groups A and B, each driven by a first and a second hydraulic pump, and either one of the groups A and B is driven. A switching valve for swivel is installed in the vehicle, and a pressure reducing valve is provided on the discharge side of the hydraulic pump that drives the group in which the switching valve for swiveling is installed. In a hydraulic circuit designed to release the swing parking brake by acting on the parking mechanical brake device, the swing switching valve is provided with a sub-valve that is switched in conjunction with the swing switching valve. Set the sub valve to switch to the shutoff oil passage position when in the neutral position, and set the sub valve to switch to the open oil passage position when the swing switching valve is in the switching position. A brake pilot switching valve is provided in a pipe line that connects the cylinder of the mechanical parking brake system and the pressure reducing valve, and the pilot pressure receiving portion of the brake pilot switching valve and the sub valve are connected via the pipe line. A hydraulic circuit for a small excavator, characterized in that a part of the pressure oil that is communicated with the pressure reducing valve and is led to a pipeline communicating with the brake pilot switching valve is passed through the sub valve.