Hydraulic system

Abstract

A hydraulic system according to an embodiment includes: a hydraulic motor that is rotatable in both directions; first and second hydraulic lines that are connected to the hydraulic motor; a brake piston that stops the hydraulic motor when advancing and that retreats when receiving working oil; a brake elastic member that elastically applies pressure to the brake piston in the advancing direction; a pressurizing pin that advances when receiving working oil, thereby applying pressure to the brake piston in the advancing direction; a pressurizing flow path that is connected at one end to the pressurizing pin to supply working oil; a pressurizing spool that opens and closes the pressurizing flow path; first and second branch flow paths that branch from the first and second hydraulic lines and that are merged into the other end of the pressurizing flow path; and a shuttle valve that is provided at the other end of the pressurizing flow path and that transmits working oil having high pressure from among working oil supplied by the first branch flow path and working oil supplied by the second branch flow path to the pressurizing flow path.

Description

TECHNICAL FIELD

[0001] The present application relates to a hydraulic system, and more particularly to a hydraulic system that rotates or stops a hydraulic motor by supplying working oil to the hydraulic motor. BACKGROUND

[0002] Generally, a hydraulic system includes a main pump for discharging working oil, and a driving device that operates using the working oil discharged from the main pump. In this case, the driving device can include a hydraulic motor and a hydraulic cylinder, etc. Also, various valves control whether or not to supply working oil and a moving direction.

[0003] Such a hydraulic system is used in various fields including construction machinery equipment. For example, a hydraulic motor used in traveling and swinging in construction machinery equipment is driven by working oil supplied from a main pump, and if the working oil is supplied, it can travel or swing, and if the supply of working oil is interrupted, it travels or swings for a while according to inertia and then stops.

[0004] Also, in order to stop the hydraulic motor, a brake device is used. A conventional mechanical brake device suitable for a hydraulic motor includes a friction plate that generates a frictional force by contacting a rotating body of the hydraulic motor, and a brake piston for applying pressure to the friction plate.

[0005] However, in a state where the hydraulic motor is stopped, in a case where a torque of the hydraulic motor is generated due to an external force, if the mechanical brake device does not generate a sufficient brake torque, there is a problem that the phenomenon that working oil inside the hydraulic motor cannot be discharged and the pressure rises occurs while the hydraulic motor rotates. For example, in a case where the hydraulic motor is used as a traveling motor of construction machinery equipment, if the construction machinery equipment is parked on a slope, a torque is generated in the hydraulic motor due to the self-weight of the construction machinery equipment, and since the construction machinery equipment has a considerable weight, it is not possible to secure a sufficient brake torque only by the mechanical brake device. SUMMARY

[0006] An embodiment of the present application provides a hydraulic system capable of stably maintaining a stopped state of a hydraulic motor.

[0007] According to an embodiment of the present invention, a hydraulic system includes: a hydraulic motor rotatable in both directions; a first hydraulic line connected to one side of the hydraulic motor; a second hydraulic line connected to the other side of the hydraulic motor; a brake piston configured to stop the hydraulic motor when advanced and to retreat when receiving hydraulic oil; a brake elastic member configured to elastically apply pressure to the brake piston in the advancing direction; a pressurizing pin configured to advance when receiving hydraulic oil, thereby applying pressure to the brake piston in the advancing direction; a pressurizing flow path connected to the pressurizing pin to supply hydraulic oil; a pressurizing spool configured to open and close the pressurizing flow path; a first branch flow path branched from the first hydraulic line and merged into the other end of the pressurizing flow path; a second branch flow path branched from the second hydraulic line and merged into the other end of the pressurizing flow path; and a shuttle valve provided at the other end of the pressurizing flow path and configured to deliver, to the pressurizing flow path, hydraulic oil having a higher pressure between hydraulic oil supplied from the first branch flow path and hydraulic oil supplied from the second branch flow path.

[0008] The hydraulic system can further include a steering valve connected to the other end of the first hydraulic line and the other end of the second hydraulic line and configured to control a moving direction of hydraulic oil supplied to the hydraulic motor.

[0009] If hydraulic oil is supplied to the hydraulic motor according to a switching operation of the steering valve, the brake piston can retreat by receiving the hydraulic oil, and the pressurizing spool can block the pressurizing flow path.

[0010] If the steering valve is neutral, the supply of hydraulic oil to the brake piston can be interrupted, and the pressurizing spool can open the pressurizing flow path.

[0011] The hydraulic system can further include a friction plate configured to contact the hydraulic motor to stop the hydraulic motor. Also, if the brake piston is advanced, a frictional force can be generated by applying pressure to the friction plate.

[0012] The hydraulic motor can include a variable swash plate. Also, the hydraulic system can further include: first and second cylinders configured to adjust an angle of the variable swash plate of the hydraulic motor; and a swash plate angle adjustment valve configured to control a supply of hydraulic oil to the first and second cylinders.

[0013] According to an embodiment of the present invention, a hydraulic system can stably maintain a stop state of a hydraulic motor. BRIEF DESCRIPTION OF DRAWINGS

[0014] Figure 1 A hydraulic circuit diagram of a hydraulic system according to an embodiment of the present invention.

[0015] Figure 2 A hydraulic circuit diagram of a hydraulic system according to an embodiment of the present invention. Figure 1A cross-sectional view of the hydraulic system.

[0016] Figure 3 According to Figure 2 A cross-sectional view of the hydraulic system along line III-III.

[0017] Figure 4 and Figure 5 To show in magnified form Figure 2 A cross-sectional view of the various operating states of the pressure valve core.

[0018] Explanation of reference numerals in the attached figures

[0019] 101: Hydraulic system;

[0020] 200: Hydraulic motor;

[0021] 204: Inclined plate;

[0022] 260: First cylinder;

[0023] 270: Second cylinder;

[0024] 400: Brake piston;

[0025] 420: Friction plate;

[0026] 450: Brake elastic component;

[0027] 500: Pressure pin;

[0028] 610: First hydraulic line;

[0029] 620: Second hydraulic line;

[0030] 650: Pressurized flow path;

[0031] 651: First branch flow path;

[0032] 652: Second branch flow path;

[0033] 720: Steering valve;

[0034] 730: Shuttle valve;

[0035] 740: Inclined plate angle adjustment valve;

[0036] 750: Pressure valve. Detailed Implementation

[0037] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings, so that those skilled in the art can easily implement the present invention. The present invention can be embodied in various different embodiments and is not limited to the embodiments described herein.

[0038] The accompanying drawings are simplified illustrations and are not shown to scale. For clarity and convenience, the relative dimensions and proportions of various parts in the drawings are shown enlarged or reduced compared to their actual size; however, these dimensions are illustrative and not limiting. Furthermore, to indicate similar features, the same reference numerals are used for the same structures, elements, or accessories shown in more than two drawings.

[0039] The embodiments of the present invention specifically illustrate ideal embodiments of the invention. Various variations of the illustrations are contemplated as a result. Therefore, the embodiments are not limited to the specific morphology of the illustrated area, and include, for example, manufacturing-based morphological variations.

[0040] The following is for reference Figures 1 to 3 This invention describes a hydraulic system 101 according to an embodiment of the present invention.

[0041] like Figures 1 to 3 As shown, a hydraulic system 101 according to an embodiment of the present invention includes a hydraulic motor 200, a first hydraulic line 610, a second hydraulic line 620, a brake piston 400, a brake elastic component 450, a pressure pin 500, a pressure flow path 650, a pressure valve core 750, a first branch flow path 651, a second branch flow path 652, and a shuttle valve 730.

[0042] Furthermore, the hydraulic system 101 of one embodiment of the present invention may also include a steering valve 720, a friction plate 420, a first cylinder 260, a second cylinder 270, and a swashplate angle adjusting valve 740.

[0043] The hydraulic motor 200 can operate by receiving working oil from a main pump (not shown). Furthermore, the hydraulic motor 200 can rotate in both directions. That is, the direction of rotation of the hydraulic motor 200 can be changed depending on the direction in which the working oil is received. As an example, the hydraulic motor 200 can be used as a travel motor for driving construction machinery. However, in one embodiment of the present invention, the hydraulic motor 200 is not limited to a travel motor.

[0044] Furthermore, in one embodiment of the present invention, the hydraulic motor 200 may include a variable ramp 204.

[0045] One end of the first hydraulic line 610 is connected to one side interface of the hydraulic motor 200, and one end of the second hydraulic line 620 is connected to the other side interface of the hydraulic motor 200. The rotation direction of the hydraulic motor 200 is changed according to the direction in which the working oil is received. For example, if the working oil is received from the first hydraulic line 610, the hydraulic motor 200 rotates to the right, and the working oil discharged from the hydraulic motor 200 moves along the second hydraulic line 620. In contrast, if the working oil is received from the second hydraulic line 620, the hydraulic motor 200 rotates to the left, and the working oil discharged from the hydraulic motor 200 moves along the first hydraulic line 610. In this case, the interface of the hydraulic motor 200, through which the working oil flows, becomes an inflow interface, and the interface from which the working oil is discharged becomes a discharge interface.

[0046] The steering valve 720 is connected to the other end of the first hydraulic line 610 and the other end of the second hydraulic line 620, and controls the moving direction of the working oil supplied to the hydraulic motor 200 from the main pump. That is, according to the operation state of the steering valve 720, the working oil supplied to the hydraulic motor 200 through the first hydraulic line 610 or the working oil supplied to the hydraulic motor 200 through the second hydraulic line 620 can be selectively selected.

[0047] The friction plate 420 is in contact with the rotating body of the hydraulic motor 200, so that the hydraulic motor 200 is stopped. Specifically, if the brake piston 400, which will be described later, advances and exerts pressure on the friction plate 420, frictional force is generated, thereby stopping the hydraulic motor 200.

[0048] If the brake piston 400 advances, it exerts pressure on the friction plate 420, thereby stopping the hydraulic motor 200. However, if the brake piston 400 is supplied with working oil, the brake piston 400 retreats and the stop state of the hydraulic motor 200 can be released.

[0049] The brake elastic member 450 elastically exerts pressure on the brake piston 400 in the advancing direction. Therefore, if the brake piston 400 is not supplied with working oil, the brake piston 400 advances while the hydraulic motor 200 is stopped by the elastic force of the brake elastic member 450. That is, the brake elastic member 450 provides a basic brake torque for stopping the hydraulic motor 200.

[0050] If the pressurizing pin 500 receives working oil, it advances and exerts pressure on the brake piston 400 in the advancing direction. That is, in the case where the brake torque is insufficient due to the elastic force of the brake elastic member 450, the pressurizing pin 500 compensates for it.

[0051] In particular, according to an embodiment of the present application, when the hydraulic motor 200 is rotated by an external force, the working oil inside the hydraulic motor 200 cannot be discharged to the outside, and thus, when a pressure rise is caused, the pressurizing pin 500 is pressed against the brake piston 400 by the pressure of the working oil.

[0052] For example, in the case where the hydraulic motor 200 is used as a traveling motor of a construction machine, if the construction machine is parked on a slope, the weight of the construction machine itself causes a considerable torque to be applied to the hydraulic motor 200, and a sufficient brake torque cannot be ensured by only the elastic force of the brake elastic member 450. Thus, the hydraulic motor 200 is rotated by an external force, and in this case, the pressure of the working oil inside the hydraulic motor 200 rises, and the pressurizing pin 500 is pushed by the pressure of the working oil to press against the brake piston 400, thereby enabling a brake torque that is insufficient by only the elastic force of the brake elastic member 450 to be additionally ensured.

[0053] As described above, in an embodiment of the present application, even without the injection of additional working oil, when the hydraulic motor 200 is rotated by an external force, the working oil inside the hydraulic motor 200 can be used to very effectively ensure a brake torque.

[0054] One end of the pressurizing flow path 650 is connected to the pressurizing pin 500, and the working oil can be supplied to the pressurizing pin 500.

[0055] The pressurizing spool 750 is provided in the pressurizing flow path 650, and can open and close the pressurizing flow path 650. That is, if the pressurizing spool 750 is opened, the working oil supplied along the pressurizing flow path 650 pushes the pressurizing pin 500.

[0056] The first branch flow path 651 can be branched from the first hydraulic line 610 and merged into the other end of the pressurizing flow path 650.

[0057] The second branch flow path 652 can be branched from the second hydraulic line 620 and merged into the other end of the pressurizing flow path 650.

[0058] The shuttle valve 730 can be provided at the other end of the pressurizing flow path 650, that is, at the merging position of the first branch flow path 651 and the second branch flow path 652, and can deliver the working oil having a high pressure among the working oil supplied by the first branch flow path 651 and the working oil supplied by the second branch flow path 652 to the above-described pressurizing flow path 650.

[0059] According to this structure, when the brake piston 400 advances to stop the hydraulic motor 200, if the hydraulic motor 200 rotates with the aid of external force, the working oil inside the hydraulic motor 200 cannot be discharged, causing the pressure in the first hydraulic line 610 or the second hydraulic line 620 to rise. That is, depending on the rotation direction of the hydraulic motor 200, the pressure in the first branch flow path 651 branching from the first hydraulic line 610 or the pressure in the second branch flow path 652 branching from the second hydraulic line 620 can increase.

[0060] In the working oil of the first branch flow path 651 and the working oil of the second branch flow path 652, the shuttle valve 730 causes the working oil with relatively high pressure to move to the pressurized flow path 650. If the pressurized valve 750 opens the pressurized flow path 650, the pressure of the working oil passing through the shuttle valve 730 is transmitted to the pressurized pin 500, and the pressurized pin 500 applies pressure to the brake piston 400.

[0061] like Figure 4 As shown, if the steering valve 720 is neutral, the supply of hydraulic fluid to the brake piston 400 is interrupted, and the pressure valve spool 750 opens the pressure flow path 650 to stop the hydraulic motor 200. Therefore, the braking torque used to stop the hydraulic motor 200 can be further ensured.

[0062] On the contrary, such as Figure 5 As shown, if working oil is supplied to the hydraulic motor 200 through the first hydraulic line 610 or the second hydraulic line 620 according to the switching action of the steering valve 720, the brake piston 400 retracts when receiving the working oil, and the pressure valve core 750 blocks the pressure flow path 650. Therefore, the braking torque disappears, and the hydraulic motor 200 can rotate.

[0063] The first cylinder 260 and the second cylinder 270 are connected to the inclined plate 204 of the hydraulic motor 200 to adjust the angle of the inclined plate 204.

[0064] The swashplate angle adjustment valve 540 adjusts the angle of the swashplate 204 by controlling the supply of working oil to the first cylinder 260 and the second cylinder 270.

[0065] According to this configuration, the hydraulic system 101 of one embodiment of the present invention can stably and effectively maintain the stopped state of the hydraulic motor 200.

[0066] While embodiments of the present invention have been described above with reference to the accompanying drawings, it will be understood by those skilled in the art that the present invention can be implemented in other specific embodiments without altering the technical concept or essential features of the present invention.

[0067] Therefore, it must be understood that the embodiments described above are only illustrative in all aspects and do not limit the present application, the scope of the present application should be indicated by the scope of the invention, not the detailed description described above, and all modified or deformed embodiments derived from the meaning, scope and equivalent concepts of the scope of the invention should be interpreted as being included in the scope of the present application.

Claims

1. A hydraulic system characterized by, comprises: a hydraulic motor capable of bidirectional rotation; a first hydraulic line connected at one end to a side port of the hydraulic motor; a second hydraulic line connected at one end to the other side port of the hydraulic motor; a brake piston that stops the hydraulic motor when advanced and that retreats when receiving working oil; a brake elastic member that elastically applies pressure to the brake piston in the advancing direction; a pressurizing pin that advances when receiving working oil, thereby applying pressure to the brake piston in the advancing direction; a pressurizing flow path connected at one end to the pressurizing pin to supply working oil; a pressurizing spool that opens and closes the pressurizing flow path; a first branch flow path branched from the first hydraulic line and merged into the other end of the pressurizing flow path; a second branch flow path branched from the second hydraulic line and merged into the other end of the pressurizing flow path; and a shuttle valve provided at the other end of the pressurizing flow path and delivering working oil having high pressure from among working oil supplied by the first branch flow path and working oil supplied by the second branch flow path to the pressurizing flow path, wherein when the hydraulic motor is rotated by external force, working oil inside the hydraulic motor cannot be discharged to the outside, the pressure of the first hydraulic line or the second hydraulic line rises, and the pressurizing pin applies pressure to the brake piston by the pressure transmitted from the first hydraulic line or the second hydraulic line.

2. The hydraulic system of claim 1, wherein, Further comprising a steering valve connected to the other end of the first hydraulic line and the other end of the second hydraulic line for controlling the moving direction of working oil supplied to the hydraulic motor.

3. The hydraulic system of claim 2, wherein, If working oil is supplied to the hydraulic motor according to switching operation of the steering valve, the brake piston retreats due to receiving working oil, and the pressurizing spool blocks the pressurizing flow path.

4. The hydraulic system of claim 2, wherein, If the steering valve is neutral, working oil supply to the brake piston is interrupted, and the pressurizing spool opens the pressurizing flow path.

5. The hydraulic system according to claim 1, further comprising a friction plate that comes into contact with the hydraulic motor to stop the hydraulic motor, if the brake piston is advanced, frictional force is generated by applying pressure to the friction plate.

6. The hydraulic system according to any one of claims 1 to 5, wherein the hydraulic motor includes a variable swash plate, the hydraulic system further comprises: first and second cylinders for adjusting the angle of the variable swash plate of the hydraulic motor; and a swash plate angle adjusting valve for controlling working oil supply to the first and second cylinders. ​

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