JP2504572Y2 - Hydraulic circuit of hydraulic excavator - Google Patents

Description

TECHNICAL FIELD This invention relates to a hydraulic circuit of a hydraulic excavator in which an engine, a hydraulic power source, etc. are mounted on a lower traveling body.

Prior Art FIG. 3 is a side view of a conventional wheel-type shovel 1. In the figure, 2 is a lower traveling body of the wheel-type shovel 1, 3 is an upper swing body, 4 is a driver's cab, 5 is an engine,
Reference numeral 6 is a swing connecting portion, 7 is a working machine mounted on the front portion of the upper swing body 3, 8 is a boom cylinder of the working machine 7, 9 is an arm cylinder, and 10 is a bucket cylinder. The swivel connecting portion 6 is composed of a swivel bearing (not shown), a swivel joint 11, and the like. FIG. 4 is a plan view showing devices and the like arranged on the upper swing body 3. In the figure, reference numerals 12, 13, 14 are a first pump, a second pump and a pilot pump, respectively, which are connected to the engine 5, 15 is a hydraulic oil tank, and 16 is a fuel tank.

In the conventional wheel type shovel 1, the engine 5,
A hydraulic pressure source such as the first pump 12, the second pump 13, the pilot pump 14, and the hydraulic oil tank 15 is mounted on the upper swing body 3.

Problems to be Solved by the Invention When a wheel type hydraulic excavator performs work on a narrow site such as in an urban area or on a main road, the rear turning radius R of the upper revolving superstructure becomes large, which makes work difficult. Alternatively, it cuts off the traffic on the main road. On the other hand, since the engine, hydraulic oil tank, and fuel tank are mounted on the upper revolving structure, the center of gravity of the vehicle body is above and the stability was poor. To solve the above problems, measures were taken to mount a wheel-type shovel engine, hydraulic power source, etc. on the undercarriage, reduce the rear-end turning radius of the upper revolving structure, and lower the center of gravity of the vehicle body. There is. However, the hydraulic circuit for traveling related thereto has not been fully considered. An object of the present invention is to provide a hydraulic circuit of a wheel type shovel in which an engine, a hydraulic power source, etc. are mounted on a lower traveling body.

Means for solving the problems a. In the present invention, the upper revolving structure is equipped with a hydraulic actuator for a working machine, the lower traveling structure is provided with a hydraulic pressure generating device such as an engine, and a plurality of actuator switching valves mounted on the vehicle body are divided into two groups. , The pressure oils from the first and second pumps are respectively supplied to the two groups, and a switching valve for controlling the traveling motor is provided in the front row of each group, and this and other actuator operating switching valves are provided. In addition to being connected in tandem, the other actuator operation switching valves are connected in parallel, and pilot pressure oil sub-valves are provided so that they can be linked to the actuator switching valves. Set to the oil passage open position, or to the oil passage cutoff position when the actuator switching valve is in the switching position. The pilot-off valve provided to each center bypass oil passage outlet side of the two groups, also provided a switchable pilot valve oil passage for the pump discharge pressure oil to the upstream side of the group, first with respect to the group,
In a hydraulic excavator in which pressure oil from the second pump is supplied by pilot control so that the hydraulic oil can be divided and joined. The first and second pilot travel valves in each of the above two groups and the pilot valves provided in the oil passages that communicate the first and second pilot travel valves are arranged in the lower traveling body. A pilot pressure oil sub-valve is provided so as to be interlocked with the first pilot travel valve, and the sub-valve is in the oil passage cutoff position when the first pilot travel valve is in the neutral position, and the pilot pump when the first pilot travel valve is in the switching position. Is set to an oil passage opening position for allowing the pilot pressure from the passage to pass, and the oil passage on the downstream side of the sub-valve is set to the pilot pressure receiving portion of the pilot valve and the pilot opening / closing valve,
And the other sub-valve of the switching valve for the actuator, and the first and second pilot travel valves are set to be interlocked by pilot pressure to perform switching operation. D. When the first and second pilot traveling valves are in the neutral position, the pressure oil from the first pump is passed through the first pilot traveling valve to one group, and the pressure oil from the second pump is passed through the pilot valve and the second pilot traveling valve. In the switching position of the first and second pilot travel valves, the pressure oil from the first pump is passed through the first pilot travel valve and the pressure oil from the second pump is sent to the pilot valve, 2 The pilot drive valve is used to jointly supply the drive motor, and when the drive motor and the working machine hydraulic actuator are simultaneously operated, the pressure oil from the first pump is supplied to the drive motor via the first pilot drive valve and to the second drive valve.
The pressure oil from the pump is supplied to the working machine hydraulic actuator through the pilot valve switching position and the second pilot travel valve.

Action a. When the wheeled shovel stops traveling and the hydraulic actuator for the working machine is operated, none of the first and second pilot travel valves, the pilot valve, and the pilot opening / closing valve are switched. Therefore, the pressure oil from the first pump is passed through the first pilot travel valve to one group,
The pressure oil from the second pump is supplied to the other group through the pilot valve and the second pilot travel valve.

B. Next, when only the first and second pilot travel valves are switched and operated, the pressure oil from the first pump passes through the first pilot travel valve and the pressure oil from the second pump travels through the pilot valve,
It is jointly supplied to the traveling motor through the second pilot traveling valve.

C. Next, when the traveling motor and the hydraulic actuator for the working machine are simultaneously operated, the pressure oil from the first pump is transferred to the traveling motor through the first pilot travel valve, and the pressure oil from the second pump is transferred to the switching position of the pilot valve. 2 It is supplied to the hydraulic actuator for work equipment through the pilot travel valve.

Embodiment Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a side view of a wheel type shovel 17 having a hydraulic circuit 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. 18
Is a lower traveling body of the wheel type shovel 17, 19 is an upper revolving body, 20 is an engine mounted on the lower traveling body 18, 21 is a hydraulic oil tank, 22 is a fuel tank, and 23 is a revolving joint.
FIG. 2 is a hydraulic circuit diagram of the wheel type shovel 17 in FIG. In the figure, 12 'is a first pump, 13' is a second pump, 14 'is a pilot pump, 24, 25, 26, 27 are actuator switching valves 28, 29, 30, 31 respectively, and actuator switching valves 24, Sub valves connected to 25, 26 and 27, 32 and 33 are pilot opening / closing valves, 34 is a first pilot travel valve (hereinafter referred to as the first travel valve), and 35 is a connection to the first travel valve 34. Is a sub valve, 36 is a second pilot travel valve (hereinafter, referred to as a second travel valve) 37 is a pilot valve, 38 is a pedal device provided in the driver's cab, and 39 is before and after a separate operation for switching the traveling direction of the lower traveling body 18. A forward switching solenoid valve, 40 is a traveling motor for driving the traveling device, and 41 and 41 'are throttles.

Next, the construction of the hydraulic circuit of the present invention will be described with reference to FIGS. In the present invention, the hydraulic actuators for the working machine mounted on the upper swing body 19 are divided into two groups A and B, and the switching valves 24, 25, 26 and 27 for the actuators of the groups A and B are all arranged in parallel. The pilot pressure oil sub-valves 28, 29, 30, 31 are connected to the switching valves 24, 25, 26, 27 respectively, and when the actuator switching valve is in the neutral position, the sub-valve is in the oil passage opening position. In addition, when the actuator switching valves 24, 25, 26 and 27 are switched, the oil passage cutoff position is set. Further, pilot opening / closing valves 32, 33 are provided on the outlet sides of the center bypass oil passages 42, 43 of the groups A, B, respectively, and the first traveling valve 34, the second traveling valve 36, and the actuator switching valves 24, 25, 26, 27 are provided. The pump pressure oil is prevented from flowing out to the oil tank 61 during the switching operation of. In the present invention, the first traveling valve 34 and the second traveling valve 3
6 and the pilot valve 37 on the upstream side of the group B to the undercarriage 18
And a pilot pressure oil sub-valve 35 is provided so as to be interlocked with the first traveling valve 34. When the first traveling valve 34 is in the neutral position, the sub-valve 35 is in the oil passage cutoff position, and the first traveling valve 34 When in the switching position, the oil passage opening position is set to allow the pilot pressure from the pilot pump 14 'to pass, and the oil passage downstream of the sub valve 35 is set to the pilot pressure receiving portion 66 of the pilot valve 37 and the pilot opening / closing valves 32, 33. The pilot pressure receiving portions 67, 68 and the sub valves 28, 29, 30, 31 of the other actuator switching valves 24, 25, 26, 27 are communicated with each other, and the first traveling valve 34, the second traveling valve 36 are also connected. Is set so as to be interlocked by pilot pressure, and when the first traveling valve 34 and the second traveling valve 36 are in the neutral position, the pressure oil from the first pump 12 'is passed through the first traveling valve 34 to the group A
The pressure oil from the second pump 13 'to the pilot valve 37, the second
It is supplied to the group B through the traveling valve 36, and when the first traveling valve 34 and the second traveling valve 36 are in the switching position, the first traveling valve 34 and the second traveling valve 36 are in the first position.
The pressure oil from the pump 12 'is supplied to the travel motor 40 through the first travel valve 34 and the pressure oil from the second pump 13' is supplied to the travel motor 40 through the pilot valve 37 and the second travel valve 36. Hydraulic actuator for work equipment (8, 9, 10, etc.)
When operating simultaneously, the pressure oil from the first pump 12 '
The traveling motor 40 is supplied with the pressure oil from the second pump 13 'through the traveling valve 34, and the switching position of the pilot valve 37 is supplied to the working machine hydraulic actuator through the second traveling valve 36.

Next, the operation of the hydraulic circuit of the present invention will be described. When the wheel type shovel 17 stops traveling and the hydraulic actuator for the working machine is activated, the travel motor pedal device 38 is not depressed. Since the pilot pressure from the pilot pump 14 'is not derived, the first traveling valve 34,
Second traveling valve 36, pilot valve 37, pilot on-off valve 32,3
None of 3 is switching. So the first pump 1
The pressure oil from 2 ′ is supplied to the oil passage 44, the neutral position of the first traveling valve 34,
It is supplied to the group A through the oil passages 45 and 46 and the swing joint 23. Further, the pressure oil from the second pump 13 'is supplied to the oil passage 47,
It is supplied to the group B via the a position of the pilot valve 37, the oil passage 48, the neutral position of the second traveling valve 36, the oil passages 49 and 50, and the swing joint 23.

Next, the forward / reverse switching solenoid valve 39 is activated to move the lower traveling body 18
The traveling direction is determined, and only the pedal device 38 is depressed.
Then, the pilot pressure from the pilot pump 14 'passes through the oil passages 51, 52, the swivel joint 23, the oil passage 53, the valve 54, the oil passage 55, the swivel joint 23, the oil passage 56, the solenoid valve 39, and the first traveling valve. 34 and the second traveling valve 36 act on the pilot pressure receiving portions 57, 58 or 59, 60, respectively. Therefore, the first traveling valve 3
4, the second traveling valve 36 is switched in conjunction with each other. However, in this case, since the actuator switching valves 24, 25, 26, 27 are all in the neutral position, their respective sub valves 28, 29, 30, 31
Is in the oil passage open position and communicates with the oil tank 61. Therefore, the pilot valve 37 and the pilot on-off valves 32, 33
Is not switching. Therefore, the pressure oil from the first pump 12 'is supplied to the oil passage 44, the C position or the D position of the first traveling valve 34, and the oil passage.
Oil is fed to the traveling motor 40 via 62 or 63. The pressure oil from the other second pump 13 'is supplied to the oil passage 47 and the pilot valve.
It is joined to the oil passage 62 or 63 through the position 37 b, the oil passage 48, the position e or the position of the second traveling valve 36, the oil passage 64 or 65, and is supplied to the traveling motor 40. Next, when the traveling motor 40 and the working machine hydraulic actuator are simultaneously operated, the first traveling valve 34 and the second traveling valve 36 are interlocked to perform switching operation, and the actuator switching valves 24, 25, 26 and 27 are operated. Either of them will switch. Therefore, the sub-valve 35 of the first traveling valve 34 is switched from the oil passage cut-off position to the oil passage open position, and at the same time, the sub-valve (28, 2
Any of 9,30,31) is switched from the oil passage open position to the oil passage cut-off position. Thereby, the pilot pressure from the pilot pump 14 'acts on the pilot pressure receiving portion 66 of the pilot valve 37 and the pilot pressure receiving portions 67 and 38 of the pilot opening / closing valves 32 and 33, respectively. So pilot valve 3
7 is switched from the a position to the b position, and the pilot opening / closing valves 32 and 33 are switched from the oil passage opening position to the oil passage shut-off position. Therefore, the pressure oil from the first pump 12 'is supplied to the traveling motor 40 through the oil passage 44 and the position c or the second position of the first traveling valve 34, while the pressure oil from the second pump 13' is supplied. The oil is supplied to the groups A and B via the pilot valve 37, the oil passage 69, the check valves 70 and 71, and the swivel joint 23.

Effect of the Invention According to the present invention, the first and second pumps arranged on the lower traveling body, the first and second pilot traveling valves, and the pilot valve on the upstream side of the group are arranged on the lower traveling body. A pilot pressure oil sub-valve is provided so that it can be linked to the travel valve, and the sub-valve is in the oil passage cutoff position when the first pilot travel valve is in the neutral position, and the pilot pressure from the pilot pump when the first pilot travel valve is in the switching position. Set to the oil passage opening position that allows
The downstream oil passages of the sub-valve are connected to the pilot pressure receiving portions of the pilot valve and the pilot opening / closing valve, and the sub-valve of the other actuator switching valve, and the first and second pilot travel valves are connected by the pilot pressure. It is set so that the switching operation is performed in conjunction with each other. Thus, when the first and second pilot travel valves are in the neutral position, the pressure oil from the first pump is passed through the first pilot travel valve to one group, and the pressure oil from the second pump is sent to the pilot valve and the second pilot. The pressure oil from the first pump is supplied to the other group through the traveling valve, and the pressure oil from the first pump is piloted through the first pilot traveling valve when the switching positions of the first and second pilot traveling valves are in the switching position. Valve and the second pilot travel valve to join and supply the travel motor, and when the travel motor and the hydraulic actuator for the working machine are simultaneously operated, the pressure oil from the first pump is supplied to the travel motor through the first pilot travel valve. Supply pressure oil from the second pump to the working machine hydraulic actuator through the pilot valve switching position and the second pilot travel valve. I am sorry. Therefore, in the hydraulic excavator equipped with the hydraulic circuit of the present invention,
The second pilot travel valve and the pilot valve can be arranged close to the travel motor and the hydraulic pump, and rational pressure oil can be applied when the travel motor is operated independently and when the travel motor and the hydraulic actuator for work machine are operated simultaneously. Supply can be done.

[Brief description of drawings]

FIG. 1 is a side view of a wheel type shovel equipped with a hydraulic circuit of the present invention, FIG. 2 is a hydraulic circuit diagram of the present invention, FIG. 3 is a side view of a conventional wheel type shovel, and FIG. FIG. 3 is a plan view showing devices and the like arranged in the upper swing body of FIG. 2,18 …… Lower traveling structure 3,19 …… Upper revolving structure 5,20 …… Engine 7 …… Working machine 12,12 ′ …… First pump 13,13 ′ …… Second pump 14,14 ′… … Pilot pump 24,25,26,27 …… Switch valve for actuator 28,29,30,31,35 …… Sub valve 32,33 …… Pilot opening / closing valve 34 …… First pilot travel valve (first travel valve) 36 …… Second pilot travel valve (second travel valve) 37 …… Pilot valve 40 …… Travel motor

Claims (1)

(57) [Scope of utility model registration request] 1. An upper revolving structure is equipped with a hydraulic actuator for a working machine, a lower traveling structure is provided with a hydraulic pressure generating device such as an engine, and a plurality of actuator switching valves mounted on a vehicle body are divided into two groups. Separately, the pressure oil from the first and second pumps is supplied to each of the two groups, and a pilot traveling valve for controlling the traveling motor is provided in the front row of each group. The valves are connected in tandem, the switching valves for operating the other actuators are connected in parallel, and a pilot pressure oil sub-valve is provided so as to be linked to the switching valves for the other actuators. In the neutral position, the sub-valve is in the oil passage open position, and in the other actuator switching valve switching position, the oil passage is shut off. In each of the above two groups, a pilot on-off valve is provided on the outlet side of the center bypass oil passage, and a pilot valve is provided on the upstream side of the group so that the oil passage for pump discharge pressure oil can be switched. In the hydraulic excavator in which the pressure oils from the first and second pumps are supplied by pilot control so that they can be divided / merged,
A pilot valve provided in an oil passage that connects the first and second pilot travel valves to the first and second pilot travel valves is arranged on the lower traveling body, and is used for pilot pressure oil so as to be interlocked with the first pilot travel valve. A sub-valve is provided and is set to the sub-valve oil passage cutoff position when the first pilot travel valve is in the neutral position, and to the oil passage opening position where the pilot pressure from the pilot pump is allowed to pass when the first pilot travel valve is in the switching position. The downstream oil passages of the sub-valve are connected to the pilot pressure receiving portions of the pilot valve and the pilot opening / closing valve, and the sub-valve of the other actuator switching valve, and the first and second pilot travel valves are connected by the pilot pressure. Set to operate in conjunction with switching,
When the first and second pilot traveling valves are in the neutral position, the pressure oil from the first pump is passed through the first pilot traveling valve to one group, and the pressure oil from the second pump is passed through the pilot valve and the second pilot traveling valve. In the switching position of the first and second pilot travel valves, the pressure oil from the first pump is passed through the first pilot travel valve and the pressure oil from the second pump is sent to the pilot valve, 2 The pilot drive valve is used to jointly supply the drive motor, and when the drive motor and the working machine hydraulic actuator are simultaneously operated, the pressure oil from the first pump is supplied to the drive motor via the first pilot drive valve and to the second drive valve.
A hydraulic circuit for a hydraulic excavator, characterized in that pressure oil from a pump is supplied to a hydraulic actuator for a working machine through a switching position of a pilot valve and a second pilot travel valve.