Rotary hydraulic system and excavator

Abstract

The utility model discloses a rotary hydraulic system and an excavator, and belongs to the technical field of engineering machinery. The rotary hydraulic system overcomes the defects that in the prior art, a traditional rotary hydraulic system is large in energy loss and hydraulic impact, noise is prone to being generated, and the service life of devices such as a rotary motor is affected. The main structure of the hydraulic system comprises a pilot system, a closed pump, a rotary motor assembly, an oil supplementing system and an energy recycling system, a pilot oil port of the pilot system is connected with an SH port of the rotary motor assembly, a PG port of the rotary motor assembly, a variable displacement mechanism of the closed pump and the energy recycling system, and the closed pump is connected with a speed reducer through the rotary motor assembly. And oil outlets of the energy recycling system and the oil recharging system are respectively connected with an oil recharging port M of the rotary motor assembly. The utility model is mainly applied to engineering machinery such as excavators and the like.

Description

Technical Field

[0001] This utility model belongs to the field of engineering machinery technology, and more specifically, it relates to a rotary hydraulic system and an excavator. Background Technology

[0002] The slewing motion of an excavator accounts for a large proportion of a single excavator work cycle, representing approximately 50%-70% of the time and 25%-40% of the energy consumption. Therefore, the design and optimization of the slewing system are extremely important. Most existing excavator slewing systems use open hydraulic systems. Open systems achieve speed regulation and reversing functions through a three-position six-way directional valve and slewing braking through a relief valve. However, this results in significant throttling and overflow losses, leading to heat consumption. Furthermore, due to the large weight of large excavators, the upper frame generates a large moment of inertia during slewing, causing significant impacts during slewing start-up, braking, and reversing, thus affecting the lifespan of the hydraulic motors.

[0003] The existing excavator swing hydraulic system includes a swing control valve, a left chamber buffer valve, a left chamber replenishing valve, a swing motor, a right chamber replenishing valve, and a right chamber buffer valve. The swing control valve is a three-position six-way directional valve that can realize the reversing of the swing motor. The left chamber buffer valve can alleviate the large pressure shock when the swing starts. The left chamber replenishing valve prevents the left chamber from sucking in air during swing braking and replenishes oil in time. The swing motor is the actuator of the swing system. The right chamber replenishing valve, the right chamber buffer valve, the oil tank, and the hydraulic pipelines connecting the various parts are also included. Its working principle is as follows: Taking the left chamber of the rotary motor as an example, when the electromagnet at the left end of the rotary control valve is energized and operates in the left position, the high-pressure oil from the pump enters the left chamber of the rotary motor through the pipeline via the left position of the rotary control valve, driving the rotary motor to rotate. The rotary motor then drives the corresponding rotary operating mechanism through the reducer. The right chamber buffer valve is connected via a pipeline, with its inlet connected to the right chamber of the rotary motor, and one end of its outlet connected to the left chamber of the rotary motor, while the other end is connected to the oil tank. The left chamber replenishing valve is connected via a pipeline, with one end of its outlet connected to the left chamber of the rotary motor, and one end of its inlet connected to the oil tank. However, the above solution has the following shortcomings:

[0004] 1) Existing technologies suffer from significant energy losses (throttling and overflow losses) during reversing, starting, and braking processes, which cannot be recovered and reused in a timely manner. Because existing excavator open slewing systems utilize a three-position six-way directional valve to adjust motor direction, start / stop speed, etc., throttling losses occur as the oil passes through the valve's orifice. Furthermore, excessive oil pressure generated during start / stop processes leads to overflow losses as excess oil flows to the oil tank through the overflow valve. There are no energy-saving solutions for recovering and reusing these losses; therefore, the open system results in substantial energy losses.

[0005] 2) Existing technology causes significant hydraulic shock during startup, braking, and reversing, which can generate noise and affect the service life of devices such as rotary motors;

[0006] 3) Existing technology cannot solve the problem of overspeed or stalling of the rotary motor. Utility Model Content

[0007] The technical problem to be solved by this utility model is to overcome the shortcomings of the prior art and to provide a rotary hydraulic system and an excavator.

[0008] To achieve the above objectives, this utility model employs the following technical solution:

[0009] A rotary hydraulic system includes a pilot system, a closed-loop pump, a rotary motor assembly, a replenishment system, and an energy recovery system. The pilot port of the pilot system is connected to the SH port and the PG port of the rotary motor assembly, the variable mechanism of the closed-loop pump, and the energy recovery system, respectively. The closed-loop pump is connected to a reducer through the rotary motor assembly. The outlets of the energy recovery system and the replenishment system are connected to the replenishment port M of the rotary motor assembly, respectively.

[0010] Preferably, the energy recovery and utilization system includes a recovery motor, a first electromagnetic reversing valve, a second electromagnetic reversing valve, a third electromagnetic reversing valve, a fourth electromagnetic reversing valve, and an accumulator. The recovery motor is connected to the first electromagnetic reversing valve, the third electromagnetic reversing valve, the fourth electromagnetic reversing valve, and the accumulator through the second electromagnetic reversing valve. The fourth electromagnetic reversing valve is also connected to the oil replenishment port M of the rotary motor assembly.

[0011] Preferably, the pilot system includes a pilot pump, a triple solenoid valve, and a pilot relief valve. The oil outlet of the pilot pump is connected to the triple solenoid valve and the pilot relief valve, respectively. The pilot oil port of the triple solenoid valve is connected to the SH port of the rotary motor assembly, the PG port of the rotary motor assembly, the variable mechanism of the closed pump, and the third solenoid directional valve, respectively. The pilot relief valve is also connected back to the hydraulic oil tank.

[0012] Preferably, the oil replenishment system includes an oil replenishment pump and an oil replenishment overflow valve. The oil outlet of the oil replenishment pump is connected to the oil replenishment overflow valve and the oil replenishment port M of the rotary motor assembly, respectively. The oil replenishment overflow valve is also connected back to the hydraulic oil tank.

[0013] Preferably, the rotary motor assembly includes a three-position three-way directional valve, a balance valve, a rotary motor, a delay valve, and a brake cylinder. The P1 port of the three-position three-way directional valve is connected to the first solenoid directional valve. The three-position three-way directional valve and the balance valve are connected in parallel. Both ends of the three-position three-way directional valve and the balance valve are respectively connected to the A port and the B port of the rotary motor. The rod chamber of the brake cylinder is connected to the delay valve.

[0014] Preferably, the balance valve is provided with a damping orifice in the middle position for buffering impact force.

[0015] Preferably, the closed-loop pump includes a pump body, a variable displacement cylinder, and an electro-proportional directional valve. The swashplate of the pump body is connected to the variable displacement cylinder, the two side chambers of the variable displacement cylinder are connected to the electro-proportional directional valve, and the electro-proportional directional valve is also connected to the pilot port of the triple solenoid valve.

[0016] Preferably, the energy recovery and utilization system further includes an overflow valve, and the recovery motor is also connected to the overflow valve through a second electromagnetic reversing valve, with the overflow valve connected back to the hydraulic oil tank.

[0017] An excavator, wherein the excavator is equipped with a slewing hydraulic system as described in any of the preceding claims.

[0018] Compared with the prior art, the beneficial effects of this utility model are:

[0019] 1. This utility model eliminates the three-position six-way reversing valve in the existing solution, reducing energy loss. By setting up an accumulator to recover the energy wasted during the start-up and braking process, and by using a three-position three-way reversing valve, the high-pressure oil during the start-up and braking process of the rotary motor can be delivered to the accumulator. The accumulator, in conjunction with the recovery motor, reuses the recovered energy in the rotary system.

[0020] 2. This utility model changes the direction of rotation of the rotary motor by reversing the forward and reverse rotation of the closed pump, and adjusts the pump displacement by adjusting the variable mechanism, thereby adjusting the speed of the rotary motor, which reduces the impact caused by the reversing valve and improves work efficiency.

[0021] 3. By setting up a balance valve, when the rotary motor stalls, the valve opening of the balance valve becomes smaller, increasing the return oil resistance of the rotary motor and generating a certain back pressure to alleviate the stall phenomenon; when the motor stops, the damping orifice in the middle position of the balance valve can connect the two working oil ports of the rotary motor to prevent reverse rotation.

[0022] In summary, this utility model can effectively meet actual rotational working conditions and has an energy recovery function, making it energy-efficient, safe, and reliable. Attached Figure Description

[0023] Figure 1 This is a hydraulic schematic diagram of the present invention;

[0024] Figure 2 This is a schematic diagram of the rotary motor assembly in this utility model;

[0025] Figure 3 This is a schematic diagram of the closed-loop pump in this utility model.

[0026] In the diagram: 1. Engine; 2. Hydraulic oil tank; 3. Pilot pump; 4. Closed-loop pump; 5. Make-up pump; 6. Recovery motor; 7. Make-up relief valve; 8. First solenoid directional valve; 9. Second solenoid directional valve; 10. Relief valve; 11. Third solenoid directional valve; 12. Fourth solenoid directional valve; 13. Accumulator; 14. Rotary motor assembly; 15. Reducer; 16. Triple solenoid valve; 17. Pilot relief valve; 41. Pump body; 42. Variable displacement cylinder; 43. Electro-proportional directional valve; 141. Three-position three-way directional valve; 142. Safety valve; 143. Check valve; 144. Balance valve; 145. Rotary motor; 146. Delay valve; 147. Brake cylinder. Detailed Implementation

[0027] The present invention will be further described below through specific embodiments and in conjunction with the accompanying drawings.

[0028] Example 1:

[0029] like Figure 1 As shown, a rotary hydraulic system includes a pilot system, a closed-loop pump 4, a rotary motor assembly 14, a replenishment system, and an energy recovery system. The pilot port of the pilot system is connected to the SH port and PG port of the rotary motor assembly 14, the variable mechanism of the closed-loop pump 4, and the energy recovery system, respectively. The closed-loop pump 4 is connected to the reducer 15 through the rotary motor assembly 14. The oil outlets of the energy recovery system and the replenishment system are connected to the replenishment port M of the rotary motor assembly 14, respectively.

[0030] Example 2:

[0031] A rotary hydraulic system differs from Embodiment 1 in that the energy recovery and utilization system includes a recovery motor 6, a first solenoid directional valve 8, a second solenoid directional valve 9, a relief valve 10, a third solenoid directional valve 11, a fourth solenoid directional valve 12, and an accumulator 13. The recovery motor 6 is connected to the first solenoid directional valve 8, the third solenoid directional valve 11, the fourth solenoid directional valve 12, and the accumulator 13 via the second solenoid directional valve 9. The fourth solenoid directional valve 12 is also connected to the oil replenishment port M of the rotary motor assembly 14. The recovery motor 6 is also connected to the relief valve 10 via the second solenoid directional valve 9, and the relief valve 10 is connected back to the hydraulic oil tank 2.

[0032] Furthermore, the pilot system includes a pilot pump 3, a triple solenoid valve 16, and a pilot relief valve 17. The oil outlet of the pilot pump 3 is connected to the triple solenoid valve 16 and the pilot relief valve 17, respectively. The pilot oil port of the triple solenoid valve 16 is connected to the SH port of the rotary motor assembly 14, the PG port of the rotary motor assembly 14, the variable mechanism of the closed pump 4, and the third solenoid directional valve 11, respectively. The pilot relief valve 17 is also connected back to the hydraulic oil tank 2.

[0033] Furthermore, the oil replenishment system includes an oil replenishment pump 5 and an oil replenishment relief valve 7. The oil outlet of the oil replenishment pump 5 is connected to the oil replenishment relief valve 7 and the oil replenishment port M of the rotary motor assembly 14, respectively. The oil replenishment relief valve 7 is also connected back to the hydraulic oil tank 2.

[0034] like Figure 2 As shown, the rotary motor assembly 14 includes a three-position three-way directional valve 141, a safety valve 142, a check valve 143, a balance valve 144, a rotary motor 145, a time delay valve 146, and a brake cylinder 147. The P1 port of the three-position three-way directional valve 141 is connected to the first solenoid directional valve 8. The three-position three-way directional valve 141 and the balance valve 144 are connected in parallel. Both ends of the three-position three-way directional valve 141 and the balance valve 144 are respectively connected to the A port and the B port of the rotary motor 145. The rod chamber of the brake cylinder 147 is connected to the time delay valve 146. The balance valve 144 has a damping orifice in the middle position for buffering impact force.

[0035] Specifically, the working principle is as follows: When the rotary motor 145 starts to rotate, the pilot oil output from the pilot pump 3 flows to the SH port of the delay valve 146, overcoming the spring force to make it work in the upper position. Another pilot oil flows through the PG port to the rod chamber of the brake cylinder 147, overcoming the brake spring force to push the brake piston rod to the right, thus releasing the brake. When braking the rotary motor 145, the pilot oil supply to the SH port is cut off. Therefore, under the action of the spring force, the delay valve 146 works in the lower position, and the oil in the rod chamber of the brake cylinder 147 returns through the lower position. The check valve 143 is used to prevent cavitation caused by insufficient oil supply to the motor. For example, if the rotary motor 145 overflows in the left chamber through the left-side safety valve 142, the hydraulic oil is replenished through the M port via the check valve 143. The safety valve 142 is used for hydraulic braking of the rotary motor 145 and to prevent excessive pressure surges during start-up and shutdown. When in the neutral position, the balance valve 144 has a damping orifice that provides a buffer for startup. During braking, it connects ports A and B of the rotary motor 145 to prevent reverse rotation. When operating in the left or right position, the valve opening of the balance valve 144 decreases, increasing the back pressure of the return oil on the low-pressure side of the rotary motor 145 and reducing the possibility of stalling or overspeeding. The three-position three-way directional valve 141 is used to introduce the overflow oil during motor startup and shutdown into the accumulator 13.

[0036] like Figure 3As shown, the closed-loop pump 4 includes a pump body 41, a variable displacement cylinder 42, and an electro-proportional directional valve 43. The swashplate of the pump body 41 is connected to the variable displacement cylinder 42, and the two side chambers of the variable displacement cylinder 42 are connected to the electro-proportional directional valve 43. The electro-proportional directional valve 43 is also connected to the pilot port of the triple solenoid valve 16. Specifically, the closed-loop pump 4 changes the direction of rotation of the pump by changing the zero position of the swashplate, thereby changing the direction of rotation of the rotary motor 145. The pilot oil in the triple solenoid valve 16 enters the chamber of the variable displacement cylinder 42 through the electro-proportional directional valve 43 to adjust the displacement of the closed-loop pump 4. For example, when the electro-proportional directional valve 43 is in the left position, the pilot oil enters the right chamber of the variable displacement cylinder 42, and the left chamber returns oil, thereby increasing the displacement of the closed-loop pump 4 and increasing the speed of the rotary motor 145.

[0037] The working principle of this utility model is as follows: Engine 1 provides power to the system. Engine 1 is coaxially connected to pilot pump 3, closed-loop pump 4, replenishing pump 5, and recovery motor 6. Pilot pump 3 outputs pilot oil to the SH and PG ports of rotary motor assembly 14 and the variable displacement mechanism of closed-loop pump 4 through a three-way solenoid valve 16. Pilot relief valve 17 acts as a safety valve for pilot pump 3, limiting the maximum pressure of pilot pump 3. Closed-loop pump 4 is a bidirectional variable displacement pump, which can rotate in both directions and has an adjustable displacement, thereby changing the speed of rotary motor 145. Replenishing pump 5 is used to replenish the oil leaked in the closed-loop system due to the operation of closed-loop pump 4 and rotary motor 145. One end of the oil outlet of replenishing pump 5 is connected to the replenishing port M of rotary motor assembly 14, and the other end is connected to replenishing relief valve 7 through a pipeline; replenishing relief valve 7 limits the maximum pressure during the replenishment process. Relief valve 10 limits the pressure of the oil released by accumulator 13 to ensure the stability of the system. The accumulator 13 is used to absorb the braking energy during the braking process of the rotary motor 145 and release the recovered energy for use in the closed-loop rotary system. The first solenoid directional valve 8, the second solenoid directional valve 9, the third solenoid directional valve 11, and the fourth solenoid directional valve 12 are all normally closed valves, used in conjunction with the accumulator 13 to achieve energy recovery and utilization. The recovery motor 6 is used to convert the hydraulic energy released by the accumulator 13 into mechanical energy, reducing the output power of the engine 1 and saving energy.

[0038] The energy recovery working principle of this utility model is as follows: When the rotary motor 145 is just started, the first electromagnetic reversing valve 8 and the fourth electromagnetic reversing valve 12 are energized (left position operation). Due to the large rotational inertia of the upper frame, an impact will be generated. Excess oil is transported to the accumulator 13 for storage through the three-position three-way reversing valve 141 in the rotary motor assembly 14, and the other electromagnetic reversing valves are de-energized. When the rotary motor 145 brakes, the first electromagnetic reversing valve 8 and the fourth electromagnetic reversing valve 12 are energized (left position operation). Although the closed pump 4 stops supplying oil, the rotary motor 145 continues to rotate due to inertia, causing the oil on the return side to be compressed and the pressure to increase. At this time, the brake overflow oil is transported to the accumulator 13 for storage through the three-position three-way reversing valve 141 in the rotary motor assembly 14, and the other electromagnetic reversing valves are de-energized.

[0039] The working principle of this utility model for energy recycling is as follows: During startup and braking, the rotary motor 145 experiences pressure surges, resulting in overflow. Although the oil replenishment pump 5 replenishes oil, insufficient replenishment still occurs, causing cavitation at these times. Therefore, during startup and braking, the fourth solenoid directional valve 12 is energized, allowing the oil recovered from the accumulator 13 to be replenished again through port M. When the rotary motor 145 rotates normally, the second and third solenoid directional valves 9 and 11 are energized, while the first and fourth solenoid valves 8 and 12 are de-energized. During this process, part of the oil stored in the accumulator 13 is supplied to the triple solenoid valve 16 to prevent insufficient pilot oil supply during sudden engine shutdown or other combined actions, thus affecting the normal operation of the system; the other part is supplied to the recovery motor 145, which, together with the engine 1, provides power to the rotation system, reducing energy consumption.

[0040] Example 3:

[0041] An excavator is provided with a slewing hydraulic system as described in Embodiment 1 or Embodiment 2 above.

Claims

1. A hydrostatic swing drive system, characterized by: The system comprises a pilot system, a closed pump (4), a rotary motor assembly (14), an oil supplement system and an energy recovery system, the pilot oil port of the pilot system is connected with SH port of the rotary motor assembly (14), PG port of the rotary motor assembly (14), variable mechanism of the closed pump (4) and the energy recovery system respectively, the closed pump (4) is connected with the speed reducer (15) through the rotary motor assembly (14), and the oil outlet of the energy recovery system and the oil supplement system is connected with the oil supplement port M of the rotary motor assembly (14) respectively.

2. The hydrostatic transmission system of claim 1, wherein: The energy recovery system comprises a recovery motor (6), a first electromagnetic switching valve (8), a second electromagnetic switching valve (9), a third electromagnetic switching valve (11), a fourth electromagnetic switching valve (12) and an accumulator (13), the recovery motor (6) is connected with the first electromagnetic switching valve (8), the third electromagnetic switching valve (11), the fourth electromagnetic switching valve (12) and the accumulator (13) through the second electromagnetic switching valve (9) respectively, and the fourth electromagnetic switching valve (12) is also connected with the oil supplement port M of the rotary motor assembly (14).

3. The hydrostatic transmission system of claim 2, wherein: The pilot system comprises a pilot pump (3), a three-way electromagnetic valve (16) and a pilot overflow valve (17), the oil outlet of the pilot pump (3) is connected with the three-way electromagnetic valve (16) and the pilot overflow valve (17) respectively, the pilot oil port of the three-way electromagnetic valve (16) is connected with SH port of the rotary motor assembly (14), PG port of the rotary motor assembly (14), variable mechanism of the closed pump (4) and the third electromagnetic switching valve (11) respectively, and the pilot overflow valve (17) is also connected with the hydraulic oil tank (2).

4. The hydrostatic transmission of claim 1 wherein: The oil supplement system comprises an oil supplement pump (5) and an oil supplement overflow valve (7), the oil outlet of the oil supplement pump (5) is connected with the oil supplement overflow valve (7) and the oil supplement port M of the rotary motor assembly (14) respectively, and the oil supplement overflow valve (7) is also connected with the hydraulic oil tank (2).

5. The hydrostatic transmission system according to any one of claims 2-4, characterized in that: The rotary motor assembly (14) comprises a three-position three-way switching valve (141), a balance valve (144), a rotary motor (145), a delay valve (146) and a brake cylinder (147), the P1 port of the three-position three-way switching valve (141) is connected with the first electromagnetic switching valve (8), the three-position three-way switching valve (141) is connected with the balance valve (144) in parallel, two ends of the three-position three-way switching valve (141) and the balance valve (144) are connected with the A port and the B port of the rotary motor (145) respectively, and the rod cavity of the brake cylinder (147) is connected with the delay valve (146).

6. The hydrostatic transmission system of claim 5, wherein: The balance valve (144) is provided with a damping hole for buffering impact force in the middle position.

7. The hydrostatic transmission of any one of claims 1-4, wherein: The closed pump (4) comprises a pump body (41), a variable cylinder (42) and an electric proportional switching valve (43), the swash plate of the pump body (41) is connected with the variable cylinder (42), the two side cavities of the variable cylinder (42) are connected with the electric proportional switching valve (43), and the electric proportional switching valve (43) is also connected with the pilot oil port of the three-way electromagnetic valve (16).

8. The hydrostatic transmission of any one of claims 2-4, wherein: The energy recovery system further comprises an overflow valve (10), the recovery motor (6) is also connected with the overflow valve (10) through the second electromagnetic switching valve (9), and the overflow valve (10) is connected with the hydraulic oil tank (2).

9. An excavator characterized by: The excavator is provided with the slewing hydraulic system as claimed in any one of claims 1-4.

Images