CN210127982U - Hydraulic system and engineering vehicle - Google Patents
Hydraulic system and engineering vehicle Download PDFInfo
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- CN210127982U CN210127982U CN201920417480.XU CN201920417480U CN210127982U CN 210127982 U CN210127982 U CN 210127982U CN 201920417480 U CN201920417480 U CN 201920417480U CN 210127982 U CN210127982 U CN 210127982U
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- 239000012530 fluid Substances 0.000 claims abstract description 136
- 238000006073 displacement reaction Methods 0.000 claims abstract description 21
- 238000004891 communication Methods 0.000 claims description 19
- 238000011144 upstream manufacturing Methods 0.000 claims description 6
- 238000007599 discharging Methods 0.000 claims description 5
- 238000005265 energy consumption Methods 0.000 abstract description 6
- 238000000034 method Methods 0.000 description 8
- 239000003921 oil Substances 0.000 description 8
- 230000008569 process Effects 0.000 description 8
- 238000013016 damping Methods 0.000 description 7
- 230000008859 change Effects 0.000 description 5
- 230000009977 dual effect Effects 0.000 description 5
- 238000010586 diagram Methods 0.000 description 3
- 230000002349 favourable effect Effects 0.000 description 2
- 230000009471 action Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 239000000446 fuel Substances 0.000 description 1
- 239000010720 hydraulic oil Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
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Abstract
The utility model relates to a hydraulic system and engineering vehicle, hydraulic system includes: the steering hydraulic cylinder (5) is used for driving the wheels to steer; a variable displacement pump (2) for providing hydraulic fluid to the steering cylinder (5); a feedback flow path (17) for feeding back the load pressure of the steering cylinder (5) to the control fluid port (X) of the variable displacement pump (2); and a pressure control section (6) including a first relief valve (61) that communicates with the feedback flow path (17) to relieve the hydraulic fluid in the feedback flow path (17) when the load pressure of the steering cylinder (5) is greater than a predetermined value. Use the technical scheme of the utility model, the higher problem of engineering vehicle's energy consumption that exists among the prior art has been improved.
Description
Technical Field
The utility model relates to an engineering equipment technical field particularly, relates to a hydraulic system and engineering vehicle.
Background
In the prior art, most of hydraulic systems of engineering vehicles such as loaders are quantitative systems, overflow loss exists, then the quantitative and variable hydraulic systems appearing are basically steering and working converging systems, the structure of the system is complex, when the working systems work, the variable pumps become quantitative pumps, the pipeline loss of the system is large, and high fuel loss is caused.
The hydraulic system of the engineering vehicle has the defects that the variable signal control is complicated, the reaction is slow and ubiquitous in the low-temperature environment, and the system response is slow when the temperature of hydraulic oil is low, so that the hydraulic system is not suitable for certain working conditions of a loader, and the efficiency of the loader is influenced.
SUMMERY OF THE UTILITY MODEL
The utility model aims at providing a hydraulic system and engineering vehicle to improve the higher problem of engineering vehicle's the energy consumption that exists among the prior art.
According to the utility model discloses an aspect of the embodiment, the utility model provides a hydraulic system, hydraulic system includes:
the steering hydraulic cylinder is used for driving the wheels to steer;
the variable pump is used for providing hydraulic fluid for the steering hydraulic cylinder;
a feedback flow path for feeding back a load pressure of the steering cylinder to a control fluid port of the variable displacement pump; and
and a pressure control portion including a first relief valve communicating with the feedback flow path to relieve the hydraulic fluid in the feedback flow path when a load pressure of the steering cylinder is greater than a predetermined value.
Optionally, the pressure control portion further includes a first throttling member provided in the feedback flow path and located upstream of the first relief valve.
Optionally, the hydraulic system further comprises a steering valve for controlling the movement of the steering cylinder, the steering valve comprising:
the reversing valve comprises an inlet communicated with the variable pump, a return port communicated with the hydraulic fluid tank, a first working port communicated with a rodless cavity of the steering hydraulic cylinder and a second working port communicated with a rod cavity of the steering hydraulic cylinder; and
a shuttle valve includes a first inlet in communication with the first working port of the reversing valve, a second inlet in communication with the second working port of the reversing valve, and an outlet in communication with the inlet end of the feedback flow path.
Optionally, the hydraulic system further comprises:
the working hydraulic cylinder is used for driving the working component to move;
a working hydraulic pump including a first hydraulic pump for supplying hydraulic fluid to the working cylinder and a second hydraulic pump for supplying hydraulic fluid to the working cylinder;
and the unloading valve is communicated with the second hydraulic pump and used for discharging the hydraulic fluid discharged by the second hydraulic pump to the hydraulic fluid tank when the load pressure of the working hydraulic cylinder is greater than a preset value.
Optionally, the unloader valve comprises a trim valve comprising:
a valve body;
the first inlet is arranged on the valve body and communicated with the second hydraulic pump;
the first outlet is arranged on the valve body and is communicated with the hydraulic fluid tank;
the valve core is movably arranged in the valve body and provided with a first position and a second position, the first inlet is communicated with the first outlet in the first position, a channel between the first inlet and the first outlet is cut off in the second position, the valve core is also provided with a third position, the third position is positioned between the first position and the second position along the moving direction of the valve core, and the flow area of the channel between the first inlet and the first outlet is smaller than that of the valve core in the first position when the valve core is positioned in the third position.
Optionally, the trim valve further comprises:
a control fluid inlet for introducing hydraulic fluid that is fed back to the load pressure of the working cylinder to urge the spool from the second position toward the first position;
a control fluid outlet for discharging hydraulic fluid when the spool moves from the second position to the first position,
a second inlet in communication with the control fluid outlet;
and a second outlet for communicating with a hydraulic fluid tank, wherein when the spool is in the first position, a passage between the second inlet and the second outlet is blocked, and when the spool is in the second position, the second inlet is communicated with the second outlet, the spool further has a third position located between the first position and the second position in a moving direction of the spool, and when the spool is in the third position, a flow area of the passage between the first inlet and the first outlet is smaller than that when the spool is in the first position, and the second inlet is communicated with the second outlet.
Optionally, the unloader valve further comprises:
the second overflow valve comprises an inlet communicated with a pipeline between the second hydraulic pump and the working hydraulic cylinder and an outlet communicated with a control fluid inlet of the buffer valve;
the control fluid flow path comprises an inlet end communicated with a control fluid inlet of the reversing valve and an outlet end communicated with the hydraulic fluid tank, and a second throttling component is arranged in the control fluid flow path;
and an inlet of the check valve is communicated with the second hydraulic pump, and the check valve is positioned on a flow path between the working hydraulic cylinders of the second hydraulic pump and is positioned at the upstream of the second overflow valve.
Optionally, the unloader valve further comprises:
a first flow path communicating the control fluid outlet and the second inlet;
a second flow path communicating the control fluid outlet and the hydraulic fluid tank; and
and a third throttling part provided in the second flow path for throttling the hydraulic fluid flowing from the control fluid outlet to the hydraulic fluid tank, the third throttling part including a one-way throttle valve including a one-way valve and a throttling part connected in parallel with the one-way valve.
According to the utility model discloses a further aspect provides an engineering machine tool, and this engineering machine tool includes foretell hydraulic system.
Optionally, the work machine comprises a loader.
By applying the technical scheme, the pressure control part comprises the first overflow valve communicated with the feedback flow path, so that hydraulic fluid in the feedback flow path is unloaded when the load pressure of the steering hydraulic cylinder is greater than a preset value, the displacement of the variable pump is reduced or adjusted to be minimum, the hydraulic system can reduce the displacement of the variable pump when the load pressure of the steering hydraulic cylinder is overlarge, the hydraulic system is favorably prevented from being damaged due to overhigh pressure, the variable pump can be prevented from continuously running under high pressure and large flow, and the energy consumption of the hydraulic system is favorably reduced.
Other features of the present invention and advantages thereof will become apparent from the following detailed description of exemplary embodiments of the invention, which proceeds with reference to the accompanying drawings.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without inventive exercise.
Fig. 1 shows a schematic structural diagram of a hydraulic system of an embodiment of the present invention;
fig. 2 shows a schematic structural diagram of an unloading valve of a hydraulic system according to an embodiment of the present invention; and;
FIG. 3 shows a pressure change curve of a working hydraulic cylinder of a hydraulic system with an unoptimized unloading valve in an unloading process;
fig. 4 shows a pressure change curve of the working hydraulic cylinder of the hydraulic system in the unloading process according to the embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative efforts belong to the protection scope of the present invention.
Fig. 1 shows a schematic configuration diagram of a hydraulic system of the present embodiment, which includes, as shown in fig. 1, a steering cylinder 5 for driving wheels to steer, a variable displacement pump 2 for supplying hydraulic fluid to the steering cylinder 5, a feedback flow path 17 for feeding back a load pressure of the steering cylinder 5 to a control fluid port X of the variable displacement pump 2, and a pressure control portion 6 provided in the feedback flow path 17.
The pressure control portion 6 includes a first relief valve 61 that communicates with the feedback flow path 17 to unload the hydraulic fluid in the feedback flow path 17 when the load pressure of the steering cylinder 5 is greater than a predetermined value, thereby reducing or minimizing the displacement of the variable displacement pump 2. The hydraulic system of this embodiment can reduce the discharge capacity of variable pump 2 when the load pressure of steering cylinder 5 is too big, is favorable to avoiding hydraulic system to produce the damage because of the pressure is too high, also can prevent that the variable pump from continuing the operation under high-pressure large-traffic to be favorable to reducing hydraulic system's energy consumption.
The pressure control portion 6 further includes a first throttling member 62, and the first throttling member 62 is provided in the feedback flow path 17 upstream of the first relief valve 61.
The hydraulic system further comprises a steering valve 4 for controlling the movement of the steering cylinder 5, the steering valve 4 comprising a directional valve 41. The directional control valve 41 includes an inlet port communicating with the variable displacement pump 2, a return port for communicating with the hydraulic fluid tank 1, a first working port communicating with the rodless chamber of the steering cylinder 5, and a second working port communicating with the rod chamber of the steering cylinder 5.
The diverter valve 4 further includes a shuttle valve 42, the shuttle valve 42 including a first inlet in communication with the first working port of the diverter valve 41, a second inlet in communication with the second working port of the diverter valve 41, and an outlet in communication with the inlet end of the feedback flow path 17.
A first inlet of the shuttle valve 42 communicates with a conduit between the first working port of the directional control valve 41 and the rodless chamber of the steering cylinder 5 and a second inlet of the shuttle valve 42 communicates with a conduit between the second working port of the directional control valve 41 and the steering cylinder 5.
The shuttle valve 42 is used to feed back the pressure of the hydraulic fluid in the rod and rodless chambers of the steering cylinder 5 to the variable displacement pump 2, so that the load pressure of the piston rod of the steering cylinder 5 during extension or retraction can be fed back to the control fluid port X of the variable displacement pump 2.
The hydraulic system further comprises a steering gear 3 and a pilot oil source valve 12 for providing hydraulic fluid to the steering gear 3. The pilot oil source valve 12 includes an inlet P1 communicating with the variable displacement pump 2, a first working port a for outputting pilot hydraulic fluid, and a second working port B for outputting pilot hydraulic fluid. Wherein the second working port B of the pilot oil source valve 12 is used to supply hydraulic fluid to the steering gear 3. The pilot oil source valve 12 is integrated with the variable displacement pump 2 and can receive the hydraulic fluid supplied from the hydraulic variable displacement pump 2 at the closest distance.
The steering gear 3 includes an inlet port P communicating with the second working port B of the pilot oil source valve 12, a return port T for communicating with the hydraulic fluid tank 1, a first working port L communicating with the first control fluid port of the selector valve 41, and a second working port R communicating with the second control fluid port of the selector valve 41.
The hydraulic fluid output from the first working port L of the steering gear 3 flows to the first control fluid port of the directional control valve 41 through the first damping member f, so that the directional control valve 41 is switched to the right position, the hydraulic fluid output from the variable displacement pump 2 is delivered to the rodless chamber of the steering cylinder 5 through the directional control valve 41, and the hydraulic steering cylinder 5 drives the vehicle to turn left.
The hydraulic fluid output from the second working port R of the steering gear 3 flows to the second control fluid port of the directional control valve 41 through the third damping member e, so that the directional control valve 41 is switched to the left position, the hydraulic fluid output from the variable displacement pump 2 is delivered to the rod chamber of the steering cylinder 5 through the directional control valve 41, and the hydraulic steering cylinder 5 drives the vehicle to steer to the right.
The hydraulic system also comprises another steering hydraulic cylinder, a rodless cavity of the steering hydraulic cylinder is communicated with the second working port of the reversing valve 41, and a rod cavity of the steering hydraulic cylinder is communicated with the first working port of the reversing valve 41, so that in the process that piston rods of the two steering hydraulic cylinders extend, a piston rod of the other steering hydraulic cylinder retracts, and the two steering hydraulic cylinders are matched to drive wheels to steer.
The hydraulic system further comprises a working cylinder 16, which working cylinder 16 is arranged to drive the movement of the work member. The working member may be one of a bucket of a loader, a boom of a crane, and an excavating arm of an excavator.
The hydraulic system further comprises a working hydraulic pump for supplying hydraulic fluid to the working hydraulic cylinder 16, the working hydraulic pump comprising a first hydraulic pump 7 and a second hydraulic pump 8, the first hydraulic pump 7 and the second hydraulic pump 8 each being independently operable to supply hydraulic fluid to the working hydraulic cylinder 16.
Optionally, the working hydraulic pump is a dual gear pump, the first hydraulic pump 7 is a first dual gear pump of the dual gear pump, and the second hydraulic pump 8 is a second dual gear pump of the dual gear pump.
The hydraulic system further comprises a working cylinder directional control valve 15 for controlling the direction of movement of the working cylinder 16, the working cylinder directional control valve 15 comprising an inlet P communicating with both the first hydraulic pump 7 and the second hydraulic pump 8, a return port T communicating with the hydraulic fluid tank 1, a first working port communicating with the rod chamber of the working cylinder 16 and a second working port communicating with the rodless chamber of the working cylinder 16.
The hydraulic system further comprises a radiator 10 and a filter 11 arranged in the line between the return port T of the working cylinder directional control valve 15 and the hydraulic fluid tank 1.
The working cylinder directional control valve 15 has a first working state and a second working state. In the first operating state, the inlet P of the hydraulic cylinder directional control valve 15 is in communication with the first working port and the return port T is in communication with the second working port. In the second working state, the inlet P of the hydraulic cylinder directional control valve 15 is communicated with the second working port and the return port T is communicated with the first working port.
The hydraulic system further comprises a pilot valve 14 for controlling the working cylinder directional control valve 15 to switch the working state, the pilot valve 14 comprising an inlet P communicating with the first working port a of the pilot oil source valve 12, a return port T communicating with the hydraulic fluid tank 1 and an outlet communicating with the control fluid port of the working cylinder directional control valve 15.
The pilot valve 14 may be a manual pilot valve and an electromagnetic pilot valve. The user controls the working component to perform work by manipulating the pilot valve 14.
The hydraulic system further includes a shutoff valve 13 provided on a flow path between the pilot valve 14 and the first working port a of the pilot oil source valve 12.
The hydraulic system further comprises an unloading valve 9 communicated with the second hydraulic pump 8, the unloading valve 9 is used for discharging the hydraulic fluid discharged by the second hydraulic cylinder 8 to the hydraulic fluid tank 1 when the load pressure of the working hydraulic cylinder 16 is larger than a preset value, when the load pressure of the working hydraulic cylinder 16 is larger than the preset value, the hydraulic fluid discharged by the second hydraulic pump 8 is not conveyed to the working hydraulic cylinder 16 any more, but directly flows back to the hydraulic fluid tank 1, the hydraulic system can prevent the second hydraulic pump 8 of the first hydraulic pump 7 from working in a high-power working state, and energy consumption of the hydraulic system is reduced.
Fig. 2 shows an enlarged view of the unloading valve 9 of the hydraulic system of the present embodiment, and as shown in fig. 1 and 2, the unloading valve 9 of the present embodiment includes an inlet P communicating with the second hydraulic pump 8 and an outlet a communicating with the inlet P of the working cylinder direction changing valve 15.
The unloading valve 9 comprises a cushion valve 22, wherein the cushion valve 22 comprises a valve body, a first inlet arranged on the valve body, a first outlet arranged on the valve body and a valve core movably arranged in the valve body, the valve core is provided with a first position and a second position, the first inlet is communicated with the first outlet at the first position, and a channel between the first inlet and the first outlet is cut off at the second position.
The unloading valve 9 further includes a second relief valve 21, and the second relief valve 21 includes an inlet communicating with a pipe between the second hydraulic pump 8 and the working cylinder 16 and an outlet communicating with a control fluid inlet of a cushion valve 22. The second relief valve 21 is configured to supply the hydraulic fluid, which urges the spool of the cushion valve 22 from the second position toward the first position, to the cushion valve 22.
The unloading valve 9 further includes a check valve 20, and the check valve 20 is located on the flow path between the working cylinders 16 of the second hydraulic pump 8 and upstream of the second relief valve 21.
When the load pressure of the working hydraulic cylinder 16 is increased, the pressure of the hydraulic fluid in the flow path between the inlet of the working hydraulic cylinder reversing valve 15 and the second hydraulic pump 8 is also increased, and when the load pressure of the working hydraulic cylinder 16 is greater than a preset value, the hydraulic fluid discharged by the second overflow valve 21 pushes the valve core of the cushion valve 22 from the second position to the first position, so that the hydraulic fluid discharged by the second hydraulic pump 8 directly flows back to the hydraulic fluid tank 1, the first hydraulic pump 7 and the second hydraulic pump 8 are prevented from working under a high-power working condition, and the reduction of the energy consumption of a hydraulic system is facilitated.
The spool also has a third position between the first position and the second position in the direction of movement of the spool, the flow area of the passage between the first inlet and the first outlet being smaller when the spool is in the third position than when the spool is in the first position. As shown in fig. 2, when the cushion valve 22 is opened due to an excessive load pressure of the hydraulic cylinder 16, the spool of the cushion valve 22 moves from the second position to the first position through the third position, the lower valve position of the cushion valve 22 in fig. 2 corresponds to the second position of the spool, the middle valve position of the cushion valve 22 in fig. 2 corresponds to the third position of the spool, and the upper valve position of the cushion valve in fig. 2 corresponds to the first position of the spool.
It can be seen that, during the opening process of the cushion valve of the unloading valve 9, the flow area of the passage between the second hydraulic pump 8 and the hydraulic fluid tank 1 is gradually increased, which is beneficial to reducing the impact and noise of the hydraulic system.
The trim valve 22 further includes a control fluid inlet for introducing hydraulic fluid that is fed back to the load pressure of the working hydraulic cylinder 16, a control fluid outlet for discharging hydraulic fluid when the spool moves from the second position to the first position, a second inlet in communication with the control fluid outlet, and a second outlet for communicating with the hydraulic fluid tank 1, the second inlet being in communication with the second outlet when the spool is in the second position.
The unloading valve 9 further comprises a control fluid flow path comprising an inlet end communicating with the control fluid inlet of the shuttle valve 22 and an outlet end for communication with the hydraulic fluid tank 1, the control fluid flow path having a second restriction member 23 disposed therein. During movement of the spool of the trim valve 22 from the first position toward the second position, hydraulic fluid discharged from the control fluid inlet of the trim valve flows through the control fluid flow path to the hydraulic fluid tank 1.
The unloader valve 9 further includes a first flow path 26 for communicating the control fluid outlet and the second inlet, a second flow path 25 for communicating the control fluid port and the hydraulic fluid tank 1, and a third throttling part 24 provided in the second flow path, the third throttling part 24 being for throttling the hydraulic fluid flowing from the control fluid outlet to the hydraulic fluid tank 1.
The second inlet port communicates with the second outlet port when the spool is in the third position, whereby it can be seen that hydraulic fluid displaced from the control fluid outlet port flows through the first flow path 26, the second inlet port and the second outlet port to the hydraulic fluid tank 1 when the spool is in the second position and the third position during movement of the spool from the second position towards the first position.
The spool is continuously movable to increase the opening degree of the trim valve 22 after reaching the first position, as shown in the upper valve position of the trim valve 22 in fig. 2, and when the spool is continuously movable to increase the opening degree of the trim valve 22 after reaching the first position, the flow of the hydraulic fluid discharged from the fluid outlet port is controlled to the hydraulic fluid tank 1 through the second flow path 25.
FIG. 3 shows a pressure change curve of a working hydraulic cylinder of a hydraulic system of which an unloading valve is not optimized in the unloading process, wherein the curve has large pressure fluctuation and high pressure peak value, and the reliability of a hydraulic element and the system is influenced;
fig. 4 shows pressure change curves of the first hydraulic pump 7 and the second hydraulic pump 8 in the unloading process of the hydraulic system, the pressure in the unloading process is stable, the pressure peak value is low, and the service life of the hydraulic system is prolonged.
In this embodiment, the variable displacement pump 2 supplies hydraulic fluid only to the steering cylinder 5, and the working hydraulic pump supplies hydraulic fluid only to the working cylinder 16.
The variable pump 2 provides hydraulic fluid for the steering hydraulic cylinder 5 independently, the steering gear 3 controls the steering valve 4 to change direction, oil output by a first working port L of the steering gear 3 controls a valve core of the steering valve 41 to move through a damping structure e and a damping structure c, the other end of the steering valve 41 is communicated with a second working port R of the steering gear 3 through a damping d and a damping f, when the steering gear rotates left, the first working port L of the steering gear outputs the hydraulic fluid, two groups of damping control reversing valve cores control stable reversing, meanwhile, a load LS signal is fed back to the variable pump 2 through the shuttle valve 42, the movement speed of the steering hydraulic cylinder 5 is controlled through the opening size of the steering valve 4, the steering speed of the machine is further controlled, when the pressure of the system reaches the set value of the pressure control part 6, a first overflow valve 61 in the pressure control part 6 is opened, a pressure difference is formed through the action of a first throttling part 62, the variable pump 2 is enabled to be discharged back, the flow is output in a small amount, the overflow loss is effectively avoided, and the hydraulic power loss is reduced to the minimum power consumption of the system due to the special design of the valve core of the steering valve core of the variable.
The working hydraulic pump is a hydraulic duplex gear pump, the first duplex gear pump (a first hydraulic pump 7) directly provides hydraulic fluid for the working hydraulic cylinder reversing valve 15, the second duplex gear pump (a second hydraulic pump 8) provides hydraulic fluid for the working hydraulic cylinder reversing valve 15 through the unloading valve 9, in the system working process, the pressure of the output port of the unloading valve 9 is increased, namely the pressure behind the check valve 20 is increased, when the pressure reaches the set pressure of the second overflow valve 21, the second overflow valve 21 is opened, the buffer valve 22 is pushed to be opened through the hydraulic fluid output by the second overflow valve 21, meanwhile, the control fluid outlet of the buffer valve 22 discharges the hydraulic fluid, and the hydraulic fluid output by the control fluid outlet flows to the hydraulic fluid tank 1 through the first flow path 26 and the second flow path 25 when the valve core of the buffer valve 22 moves, so that the buffer valve 22 can be opened quickly. Then, as the spool of the cushion valve 22 moves, the passage between the second outlet and the second inlet is cut off, the hydraulic fluid discharged from the control fluid outlet of the cushion valve 22 can only flow to the hydraulic fluid tank 1 through the second flow path 25, the moving speed of the spool of the cushion valve is slowed down, and the spool of the cushion valve 22 moves slowly to increase the opening of the cushion valve 22 to the maximum opening slowly, so that the cushion valve 22 is opened quickly, pressure shock caused by untimely unloading of the second gear pump is avoided, and meanwhile, the second gear pump is unloaded step by step, and noise caused by unloading is avoided.
When the machine is in steering operation, the hydraulic variable pump 2 supplies hydraulic fluid to the steering hydraulic cylinder as required, when the working part of the engineering vehicle works, the working hydraulic pump supplies hydraulic fluid to the working hydraulic cylinder 16, the steering system and the working system are mutually independent, mutual interference is avoided, and the reliability and the working efficiency of the steering and working systems are improved.
According to another aspect of the present invention, the present embodiment further provides an engineering vehicle, which includes the above-mentioned hydraulic system.
The above description is only exemplary embodiments of the present invention, and should not be construed as limiting the present invention, and any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. A hydraulic system, comprising:
the steering hydraulic cylinder (5) is used for driving the wheels to steer;
a variable displacement pump (2) for providing hydraulic fluid to the steering cylinder (5);
a feedback flow path (17) for feeding back the load pressure of the steering cylinder (5) to a control fluid port (X) of the variable displacement pump (2); and
a pressure control section (6) including a first relief valve (61) communicating with the feedback flow path (17) to relieve the hydraulic fluid in the feedback flow path (17) when the load pressure of the steering cylinder (5) is greater than a predetermined value.
2. The hydraulic system according to claim 1, characterized in that the pressure control portion (6) further includes a first throttling member (62), the first throttling member (62) being provided in the feedback flow path (17) upstream of the first relief valve (61).
3. The hydraulic system according to claim 1, characterized in that it further comprises a steering valve (4) for controlling the movement of the steering hydraulic cylinder (5), the steering valve (4) comprising:
a reversing valve (41) comprising an inlet communicated with the variable displacement pump (2), a return port for communicating with a hydraulic fluid tank (1), a first working port communicated with a rodless cavity of the steering hydraulic cylinder (5), and a second working port communicated with a rod cavity of the steering hydraulic cylinder (5); and
a shuttle valve (42) including a first inlet in communication with the first working port of the directional valve (41), a second inlet in communication with the second working port of the directional valve (41), and an outlet in communication with an inlet end of the feedback flow path (17).
4. The hydraulic system of claim 1, further comprising:
the working hydraulic cylinder (16) is used for driving the working component to move;
-a working hydraulic pump comprising a first hydraulic pump (7) for providing hydraulic fluid to the working hydraulic cylinder (16) and a second hydraulic pump (8) for providing hydraulic fluid to the working hydraulic cylinder (16);
and an unloading valve (9) communicated with the second hydraulic pump (8) and used for discharging the hydraulic fluid discharged by the second hydraulic pump (8) to a hydraulic fluid tank (1) when the load pressure of the working hydraulic cylinder (16) is larger than a preset value.
5. The hydraulic system according to claim 4, characterized in that the unloading valve (9) comprises a trim valve (22), the trim valve (22) comprising:
a valve body;
the first inlet is arranged on the valve body and communicated with the second hydraulic pump (8);
a first outlet arranged on the valve body and used for communicating with a hydraulic fluid tank (1);
and the valve core is movably arranged in the valve body and provided with a first position and a second position, the first inlet is communicated with the first outlet in the first position, a channel between the first inlet and the first outlet is blocked in the second position, the valve core is also provided with a third position, the third position is positioned between the first position and the second position along the moving direction of the valve core, and the flow area of the channel between the first inlet and the first outlet is smaller than that of the channel when the valve core is positioned at the first position.
6. The hydraulic system of claim 5, wherein the trim valve (22) further comprises:
a control fluid inlet for introducing hydraulic fluid that is fed back to the load pressure of the working hydraulic cylinder (16) to urge the spool from the second position to the first position;
a control fluid outlet that discharges hydraulic fluid when the spool moves from the second position to the first position,
a second inlet in communication with the control fluid outlet;
a second outlet for communication with a hydraulic fluid tank (1), the passage between the second inlet and the second outlet being blocked when the spool is in the first position, the second inlet being in communication with the second outlet when the spool is in the second position, the spool further having a third position located between the first position and the second position in the direction of movement of the spool, the flow area of the passage between the first inlet and the first outlet being smaller when the spool is in the third position than when the spool is in the first position, and the second inlet being in communication with the second outlet.
7. A hydraulic system according to claim 6, characterized in that the unloading valve (9) further comprises:
a second relief valve (21) comprising an inlet communicating with the line between the second hydraulic pump (8) and the working cylinder (16) and an outlet communicating with the control fluid inlet of the cushion valve (22);
a control fluid flow path including an inlet end communicating with a control fluid inlet of the trim valve (22) and an outlet end for communicating with the hydraulic fluid tank (1), the control fluid flow path having a second throttling member (23) disposed therein;
and an inlet of the check valve (20) is communicated with the second hydraulic pump (8), and the check valve (20) is positioned on a flow path between working hydraulic cylinders (16) of the second hydraulic pump (8) and is positioned at the upstream of the second overflow valve (21).
8. A hydraulic system according to claim 6, characterized in that the unloading valve (9) further comprises:
a first flow path (26) communicating the control fluid outlet and the second inlet;
a second flow path (25) communicating the control fluid outlet and the hydraulic fluid tank (1); and
-a third throttling member (24) arranged in the second flow path (25) for throttling the hydraulic fluid flowing from the control fluid outlet to the hydraulic fluid tank (1), the third throttling member (24) comprising a one-way throttle comprising a one-way valve and a throttling member connected in parallel with the one-way valve.
9. A work vehicle, characterized in that it comprises a hydraulic system according to any one of claims 1-8.
10. The work vehicle of claim 9, characterized in that the work vehicle comprises a loader.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201920417480.XU CN210127982U (en) | 2019-03-29 | 2019-03-29 | Hydraulic system and engineering vehicle |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201920417480.XU CN210127982U (en) | 2019-03-29 | 2019-03-29 | Hydraulic system and engineering vehicle |
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| CN210127982U true CN210127982U (en) | 2020-03-06 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN201920417480.XU Withdrawn - After Issue CN210127982U (en) | 2019-03-29 | 2019-03-29 | Hydraulic system and engineering vehicle |
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| CN (1) | CN210127982U (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109973450A (en) * | 2019-03-29 | 2019-07-05 | 徐工集团工程机械股份有限公司科技分公司 | Hydraulic system and engineering truck |
-
2019
- 2019-03-29 CN CN201920417480.XU patent/CN210127982U/en not_active Withdrawn - After Issue
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109973450A (en) * | 2019-03-29 | 2019-07-05 | 徐工集团工程机械股份有限公司科技分公司 | Hydraulic system and engineering truck |
| CN109973450B (en) * | 2019-03-29 | 2024-05-14 | 徐工集团工程机械股份有限公司科技分公司 | Hydraulic system and engineering vehicle |
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