阅读说明：本技术 双泵联控液压打桩锤 (Double-pump combined control hydraulic pile hammer ) 是由 施光林 张静 许清 孟春明 冯启阳 王小娟 于 2019-11-27 设计创作，主要内容包括：本发明公开了一种双泵联控液压打桩锤,包括锤芯和液压缸,液压缸上分别设有与其上下缸腔相连通的下缸腔油口和上缸腔油口；下缸腔油泵的出油口连至下缸腔液动阀的压力油P口,下缸腔液动阀的A油口连向下缸腔油口,上缸腔油泵的出油口连至上缸腔液动阀的压力油口P口,上缸腔液动阀的A油口连向上缸腔油口；所述下缸腔液动阀的压力油口P口与上缸腔液动阀的控制油口X口连通,下缸腔液压阀的A油口经过第一节流器与上缸腔液动阀的控制油口X口连通；所述上缸腔液动阀的压力油口P口与下缸腔液动阀的控制油口X口连通,上缸腔液动阀的A油口经过第二动节流器与下缸腔液动阀的控制油口X口连通。该打桩锤具有结构简单紧凑、工作高效可靠的优势。(The invention discloses a double-pump combined control hydraulic pile hammer, which comprises a hammer core and a hydraulic cylinder, wherein a lower cylinder cavity oil port and an upper cylinder cavity oil port which are communicated with an upper cylinder cavity and a lower cylinder cavity of the hydraulic cylinder are respectively arranged on the hydraulic cylinder; the oil outlet of the lower cylinder cavity oil pump is connected to a pressure oil port P of the lower cylinder cavity hydraulic valve, an oil port A of the lower cylinder cavity hydraulic valve is connected to an oil port P of the lower cylinder cavity, the oil outlet of the upper cylinder cavity oil pump is connected to a pressure oil port P of the upper cylinder cavity hydraulic valve, and an oil port A of the upper cylinder cavity hydraulic valve is connected to an oil port of the upper cylinder cavity; a pressure oil port P of the lower cylinder cavity hydraulic valve is communicated with a control oil port X of the upper cylinder cavity hydraulic valve, and an oil port A of the lower cylinder cavity hydraulic valve is communicated with the control oil port X of the upper cylinder cavity hydraulic valve through a first throttler; and an oil port A of the upper cylinder cavity hydraulic valve is communicated with a control oil port X of the lower cylinder cavity hydraulic valve through a second movable throttler. The pile hammer has the advantages of simple and compact structure and high-efficiency and reliable work.)

1. The utility model provides a double pump allies oneself with accuse hydraulic pile hammer, includes hammer core (13) and hammer core guide (10), and this hammer core (13) can support on hammer core guide (10) with reciprocating sliding, and fixed mounting has pneumatic cylinder (1) on hammer core guide (10), and the piston rod (7) of pneumatic cylinder (1) are extended to hold and are connected its characterized in that with hammer core (13): a lower cylinder cavity oil port (2) communicated with the lower cylinder cavity of the hydraulic cylinder is arranged on the hydraulic cylinder (1), and an upper cylinder cavity oil port (4) communicated with the upper cylinder cavity of the hydraulic cylinder is also arranged on the hydraulic cylinder (1); an oil outlet of the lower cylinder cavity oil pump (18) is communicated to a pressure oil port P of the lower cylinder cavity hydraulic valve (20), an oil port A of the lower cylinder cavity hydraulic valve (20) is connected to the lower cylinder cavity oil port (2), an oil outlet of the upper cylinder cavity oil pump (25) is communicated to a pressure oil port P of the upper cylinder cavity hydraulic valve (23), and an oil port A of the upper cylinder cavity hydraulic valve (23) is connected to the upper cylinder cavity oil port (4); a pressure oil port P of the lower cylinder cavity hydraulic valve (20) is communicated with a control oil port X of the upper cylinder cavity hydraulic valve (23), and an oil port A of the lower cylinder cavity hydraulic valve (20) is communicated with the control oil port X of the upper cylinder cavity hydraulic valve (23) through a first restrictor (21); and an oil port A of the upper cylinder cavity hydraulic valve (23) is communicated with a control oil port X of the lower cylinder cavity hydraulic valve (20) through a second movable restrictor (22).

2. The dual-pump combined-control hydraulic pile driving hammer as recited in claim 1, wherein: and the lower cylinder cavity hydraulic valve (20) and the upper cylinder cavity hydraulic valve (23) are both two-position three-way hydraulic reversing valves.

3. The dual-pump combined-control hydraulic pile driving hammer as recited in claim 1, wherein: and the driving motors of the lower cylinder cavity oil pump (18) and the upper cylinder cavity oil pump (25) are servo motors or variable frequency motors.

4. The dual-pump combined-control hydraulic pile driving hammer as recited in claim 1, wherein: the first throttling device (21) and the second throttling device (23) are straight-through type fixed throttling valves.

5. The dual-pump combined-control hydraulic pile driving hammer as recited in claim 1, wherein: the hydraulic cylinder (1) is a single-rod piston type hydraulic cylinder.

6. The dual-pump combined-control hydraulic pile driving hammer as recited in claim 1, wherein: the hydraulic cylinder (1) is a double-rod piston type hydraulic cylinder.

7. The dual-pump combined-control hydraulic pile driving hammer as recited in claim 1, wherein: the hammer core guide piece (10) adopts a cylinder type guide structure, and the hammer core (13) is arranged in the guide cylinder in a sliding mode.

8. The dual-pump combined-control hydraulic pile driving hammer as recited in claim 1, wherein: the hammer core guide piece (10) comprises two guide rods which are parallel to each other, and the hammer core (13) is supported on the guide rods in a sliding mode.

Technical Field

The invention relates to a piling machine for foundation construction of constructional engineering, in particular to a hydraulic piling hammer with double oil supply pumps.

Background

The hammering type pile driver is the most common piling machinery and has the characteristics of large impact energy, high piling efficiency and convenient construction, so that the hammering type pile driver can only be used for operation in pile sinking construction of large foundation piles.

The hammering type pile driver mainly comprises a diesel pile driving hammer and a hydraulic pile driving press hammer. The diesel pile hammer is forbidden to use gradually due to the problems of noise, vibration, oil smoke pollution and the like which cannot be solved by the structure of the diesel pile hammer; and because the heat capacity and the efficiency of the diesel pile hammer are limited, the impact hammer core of the diesel pile hammer can only reach 15 tons theoretically, and the construction requirement of a large precast pile cannot be met. The hydraulic pile hammer has the characteristics of high pile driving efficiency, low noise, small vibration and no oil smoke pollution, the advancement of the hydraulic pile hammer is widely accepted, the hydraulic pile hammer is inevitably used for replacing a diesel pile hammer, and the hydraulic pile hammer completely replaces the diesel pile hammer in countries developed in the west and countries and regions such as Japan, Korea, hong Kong, Singapore and the like in Asia and becomes an absolute principal force of a pile driving market.

The applicant proposes an invention patent application of 'guide rod type pile driving hammer with hydraulic cartridge valve' in 2017, 10, 24, and the patent application numbers are as follows: 201711003379.1. the hydraulic control loop of the hydraulic pile hammer comprises hydraulic valves such as a pilot control valve, a cartridge valve, an overflow throttle valve and the like, the working structure and the working principle of the hydraulic control loop form a single-action hydraulic impact pile hammer, and a pile hammer core strikes a pile body in a free-falling mode; when the hammer is lifted, the pressure oil of the hydraulic pump is filled into the lower cavity of the hydraulic cylinder through the first cartridge valve and the second cartridge valve at a certain pressure value under the control of the pilot control valve, so that the hammer is lifted. When the hammer falls, the first cartridge valve is closed first, and then the second cartridge valve is opened. The longer opening and closing action time of the cartridge valve and the hydraulic oil flow loss can be formed in the striking of each lifting hammer and each dropping hammer, and the improvement of the striking energy and the striking frequency of the pile driving hammer is influenced. The hydraulic control loop needs linkage switching of a plurality of main valves when reversing, so that not only is the complexity of an oil way increased and the reliability of a transmission system reduced, but also the time of reversing action is increased due to multi-stage switching, the response speed is slowed down, the working time of each striking period is long, high-frequency piling is difficult to realize, and the improvement of the construction efficiency of a pile foundation is influenced.

The applicant also proposes patent application of 'high-frequency high-energy hydraulic pile driving hammer' in 2018, 3 and 30, and the patent application numbers are as follows: 201810291946.6. the hydraulic cylinder in the application adopts a differential sleeve cylinder structure, so that the double-acting hydraulic pile hammer is formed, but a hydraulic control loop of the hydraulic cylinder also comprises a plurality of hydraulic control elements such as cartridge valves and the like. When the hammer is lifted, the second cartridge valve is closed, the first cartridge valve is opened, and pressure oil of the hydraulic pump is directly filled into a straight rod cavity of the hydraulic cylinder; when the pile hammer strikes, the second cartridge valve is opened, the first cartridge valve is closed, the hydraulic cylinder forms a differential connection loop, the hydraulic control loop formed by sequential linkage opening and closing of the plurality of cartridge valves still has small flow, large pressure loss and low action sensitivity, and the improvement of the striking energy and the striking speed of the pile hammer is limited.

Therefore, although the existing hydraulic pile hammer has the advantage that diesel pile driving cannot be replaced, the hydraulic control loops of the existing hydraulic pile hammer are complex, the existing hydraulic pile hammer comprises a high-power hydraulic pump and a main control reversing valve, and also comprises hydraulic elements such as a pilot valve and an overflow throttle valve, and more high-pressure oil flow loss is generated due to excessive overflow and throttling in the working process of lifting and dropping the hammer, so that when the hitting energy of the hydraulic hammer needs to be improved, the hydraulic pump and the hydraulic control loops are inevitably required to have higher system flow, more energy loss is brought, the hydraulic control system and the power elements are more complex and huge, and the conversion efficiency of hydraulic energy to hitting energy is directly influenced. The increase of energy loss and the reduction of conversion efficiency bring the increase of system heat productivity, so that the temperature rise of a hydraulic system is improved, the viscosity of hydraulic oil is reduced, the leakage amount is increased, and the volumetric efficiency of a hydraulic pump and the efficiency of the whole system are obviously reduced. Particularly, when high-frequency piling is carried out, the viscosity of hydraulic oil is reduced, oil films of moving parts such as a slide valve and the like are thinned or cut, the friction resistance is increased, the abrasion is aggravated, and higher temperature rise is brought. The rise of the temperature rise of the hydraulic system can also cause the deformation of the rubber sealing element and accelerate the aging of the sealing element; resulting in a reduction in clearance or seizure between the hydraulically moving parts, causing malfunction of the action. The complicated hydraulic system can also cause the hydraulic pipeline to become long, and the connector increases, and the fault rate improves, influences the continuous stable work of pile hammer lastingly, especially under the high vibrating operating mode of strong impact of pile hammer, and complicated hydraulic system breaks down more easily and influences the high-efficient operation of pile hammer. The existing hydraulic control system of the pile hammer takes a single hydraulic pump as a driving source, and a plurality of hydraulic reversing valves control the reversing of a hydraulic cylinder; the control method ensures that the striking energy and the striking stroke of the hydraulic hammer are often difficult to be instantly adjusted according to the construction condition, and limits the use flexibility and the application range of the hydraulic hammer.

Disclosure of Invention

The invention aims to solve the technical problem of providing a double-pump combined control hydraulic pile hammer which is simple and compact in structure, efficient and reliable in work.

In order to solve the technical problem, the double-pump combined control hydraulic pile hammer comprises a hammer core and a hammer core guide piece, wherein the hammer core can be supported on the hammer core guide piece in a reciprocating sliding manner; the oil outlet of the lower cylinder cavity oil pump is communicated to a pressure oil port P of the lower cylinder cavity hydraulic valve, an oil port A of the lower cylinder cavity hydraulic valve is connected to an oil port P of the lower cylinder cavity, the oil outlet of the upper cylinder cavity oil pump is communicated to a pressure oil port P of the upper cylinder cavity hydraulic valve, and an oil port A of the upper cylinder cavity hydraulic valve is connected to an oil port of the upper cylinder cavity; a pressure oil port P of the lower cylinder cavity hydraulic valve is communicated with a control oil port X of the upper cylinder cavity hydraulic valve, and an oil port A of the lower cylinder cavity hydraulic valve is communicated with the control oil port X of the upper cylinder cavity hydraulic valve through a first throttler; and an oil port A of the upper cylinder cavity hydraulic valve is communicated with a control oil port X of the lower cylinder cavity hydraulic valve through a second movable throttler.

In the structure, the hydraulic cylinder is used as a power source of the pile hammer, so that high-strength noise caused by violent blasting vibration and explosion impact can not be generated in the working process, air pollution caused by pollutants such as harmful smoke particles and the like can not be generated, clean construction can be realized, the influence on the surrounding environment is small, and increasingly strict environmental protection requirements can be easily met; the hydraulic cylinder is adopted as a power source and has the characteristic of high energy efficiency, and most of hydraulic energy generated by the hydraulic pump is converted into potential energy of the striking hammer body; the hydraulic cylinder forms a series and standardized product, has a reasonable structure and is convenient to implement and maintain. And because the two hydraulic pumps are adopted to respectively drive the upper hydraulic cavity and the lower hydraulic cavity of the hydraulic cylinder to form independent drive of the upper cavity and the lower cavity of the hydraulic cylinder, the hammer lifting speed of the pile hammer and the drop hammer striking energy of the pile hammer can be conveniently adjusted by adjusting the oil feeding amount of the upper oil cavity and the lower oil cavity, the striking stroke of the hammer core of the pile hammer can be conveniently adjusted by independently driving the upper cavity and the lower cavity of the hydraulic cylinder, the construction requirements of construction working conditions such as different pile foundation soil conditions and the like can be well met by quickly adjusting the striking energy and the striking stroke of the pile hammer, and the use flexibility and the construction adaptability of the pile hammer are greatly improved. Furthermore, the hydraulic control loop adopts a linkage control structure that one pump controls the other pump to correspond to the reversing valve, so that an extremely compact and reasonable hydraulic control loop is formed, a power unit of the pile hammer is greatly simplified, the flow loss of overflow and throttling in the control loop is greatly reduced, the efficiency of converting hydraulic energy into hammering energy is effectively improved, the energy loss is effectively reduced, the defect caused by overhigh temperature rise of the system is avoided, the advantage of large hammering energy of the hydraulic pile hammer is better played, and the pile hammer is more suitable for pile driving construction of various pile types and various geological conditions; the improvement of the energy conversion efficiency also avoids the unfavorable working condition caused by overhigh temperature rise in the hydraulic loop, thereby not only ensuring the stability of the viscosity of the hydraulic oil, reducing the leakage probability of the hydraulic oil, improving the working stability and reliability of hydraulic moving parts such as a slide valve and the like, but also effectively improving the action flexibility and the service life of a sealing element and a mechanical part. The compact hydraulic control loop also greatly reduces and shortens the length and the joint of the pipeline, effectively reduces the faults caused by the impact vibration of the pile hammer, and has more reliable work and more efficient operation.

In a preferred embodiment of the invention, the lower cylinder cavity hydraulic valve and the upper cylinder cavity hydraulic valve are both two-position three-way hydraulic reversing valves. The reversing regulation and control of the hydraulic cylinder are realized.

In a preferred embodiment of the present invention, the driving motors of the lower cylinder cavity oil pump and the upper cylinder cavity oil pump are servo motors or variable frequency motors. The control of the system flow can be conveniently realized, so that the striking energy and the striking stroke of the pile hammer can be flexibly adjusted.

In a preferred embodiment of the present invention, the first and second restrictors are straight-through fixed-throttle valves. And the control oil pressure of the hydraulic reversing valve can be reliably formed.

Preferably, the hydraulic cylinder is a single-rod piston type hydraulic cylinder.

Preferably, the hydraulic cylinder is a double rod piston type hydraulic cylinder.

Preferably, the hammer core guide part adopts a cylinder type guide structure, and the hammer core is arranged in the guide cylinder in a sliding manner.

Preferably, the hammer core guide comprises two guide rods parallel to each other, and the hammer core is slidably supported by the guide rods.

Drawings

The dual-pump combined control hydraulic pile driving hammer is further described with reference to the accompanying drawings and the detailed description.

FIG. 1 is a schematic structural view of the mechanical part of one embodiment of the dual pump combined control hydraulic pile hammer of the present invention;

FIG. 2 is a schematic diagram illustrating the hydraulic control circuit and the oil passage structure of the hydraulic cylinder according to the embodiment shown in FIG. 1;

fig. 3 is a schematic diagram showing the hydraulic control circuit and the oil passage structure of the hydraulic cylinder according to another embodiment of the present invention.

In the figure, 1-hydraulic cylinder, 2-lower cylinder cavity oil port, 3-cylinder body seat, 4-upper cylinder cavity oil port, 5-cylinder body support piece, 6-cylinder cover, 7-piston rod, 8-connecting sleeve, 9-coupling, 10-hammer core guide piece, 11-hammer core connecting rod, 12-butterfly spring, 13-hammer core, 14-alternate-beating piston, 15-alternate-beating piston sleeve, 16-inner cylinder sleeve, 17-outer cylinder sleeve, 18-lower cylinder cavity oil pump, 19-lower cylinder cavity oil pump one-way valve, 20-lower cylinder cavity hydraulic valve, 21-first restrictor, 22-second restrictor, 23-upper cylinder cavity hydraulic valve, 24-upper cylinder cavity oil pump one-way valve, 25-upper cylinder cavity oil pump, 26-oil tank.

Detailed Description

The double-pump combined control hydraulic pile driving hammer (the hammer core is in the pile driving position) shown in fig. 1, wherein the hammer core 13 of the hydraulic pile driving hammer is a cylindrical alloy steel casting with the weight of fifty tons, and the outer diameter of the cylindrical hammer core is 1.5 meters, and the height of the cylindrical hammer core is 5.1 meters; the hammer core guide 10 adopts a cylindrical guide structure, namely the hammer core guide 10 is in a steel cylindrical structure, and the hammer core 13 can be vertically and reciprocally slidably arranged in a cylindrical pipe of the hammer core guide 10. The lower end of the tubular hammer core guide piece 10 is fixedly connected with a secondary striking piston sleeve 15 through a guide piece connecting flange, the secondary striking piston sleeve 15 also adopts a tubular structure, a secondary striking piston 14 is movably placed in the secondary striking piston sleeve 15, the upper top surface of the secondary striking piston 14 is directly struck by a drop hammer of the hammer core 13 during striking, the lower bottom surface of the secondary striking piston 14 is an arc-shaped surface, and the secondary striking piston 14 is supported on the pile top of the base pile through the arc-shaped surface; the drop hammer striking force of the hammer core 13 is transmitted to the foundation pile through the secondary striking piston 14, so that the pile head is effectively protected from being damaged by the striking injury.

The cylinder cover 6 at the lower end of the hydraulic cylinder 1 of the pile hammer is fixedly connected and supported on the lower support flange, and the upper end of the hydraulic cylinder 1 is fixedly supported on the upper support flange through the cylinder bottom and the cylinder base 3; the upper supporting flange and the lower supporting flange are fixedly connected with each other through the cylinder body supporting piece 5, so that a stable frame structure is formed, the hydraulic cylinder 1 is located in the center of the rigid frame, a hydraulic cylinder sheath is further sleeved on the outer side face of the hydraulic cylinder 1, and the hydraulic cylinder sheath is fixedly arranged between the upper supporting flange and the lower supporting flange. The lower supporting flange is fixedly arranged at the upper end of the hammer core guide 10 in a cylindrical structure through the connecting sleeve 8 and the sleeve connecting flange, and the structure is favorable for installation and maintenance of the hydraulic cylinder. The upper supporting flange is fixedly connected with a hammer lifting cylinder, hydraulic elements such as an integrated valve block and a hydraulic pump are arranged in the hammer lifting cylinder, and a hammer lifting lug is arranged at the top of the hammer lifting cylinder so as to lift the whole pile.

As shown in fig. 2, the hydraulic cylinder 1 is a single-rod piston type hydraulic cylinder, the hydraulic cylinder 1 comprises an inner cylinder sleeve 16 and an outer cylinder sleeve 17 which are concentrically sleeved at intervals, and an oil inlet channel is formed between gaps of the inner cylinder sleeve 16 and the outer cylinder sleeve 17. The upper ends of the inner cylinder sleeve 16 and the outer cylinder sleeve 17 are fixedly welded with a cylinder body base 3, a cylinder bottom is fixedly connected to the cylinder body base 3, and a lower cylinder cavity oil port 2 and an upper cylinder cavity oil port 4 are arranged on the cylinder bottom. A piston is movably arranged in the inner cylinder sleeve 16, the lower end of the piston is fixedly connected with a piston rod 7, an oil port 2 of a lower cylinder cavity is communicated with an oil inlet channel between the inner cylinder sleeve 16 and the outer cylinder sleeve 17 through a corresponding flow channel on a cylinder body seat, and the oil inlet channel is connected to a lower cavity (rod cavity) of the inner cylinder sleeve of the hydraulic cylinder through an oil inlet hole at the lower end of the inner cylinder sleeve 16; the upper cylinder cavity oil port 4 is communicated with an upper cavity (rodless cavity) of the hydraulic cylinder. The lower end of a piston rod 7 of the hydraulic cylinder 1 extends outwards and is connected with a hammer core connecting rod 11 through a coupling 9, and the hammer core connecting rod 11 is connected with a hammer core 13 through a butterfly spring 12.

The hydraulic control circuit portion of the pile hammer includes a lower cylinder chamber oil pump 18 and an upper cylinder chamber oil pump 25. The oil outlet of the lower cylinder cavity oil pump 18 is communicated to a pressure oil port P of the lower cylinder cavity hydraulic valve 20 through a lower cylinder cavity oil pump one-way valve 19, the oil port A of the lower cylinder cavity hydraulic valve 20 is connected to the lower cylinder cavity oil port 2, the oil outlet of the upper cylinder cavity oil pump 25 is communicated to the pressure oil port P of the upper cylinder cavity hydraulic valve 23 through an upper cylinder cavity oil pump one-way valve 24, and the oil port A of the upper cylinder cavity hydraulic valve 23 is connected to the upper cylinder cavity oil port 4. The lower cylinder chamber hydraulic valve 20 and the upper cylinder chamber hydraulic valve 23 are both two-position three-way hydraulic reversing slide valves. The driving motors of the lower cylinder cavity oil pump 18 and the upper cylinder cavity oil pump 25 are variable frequency motors and can also be servo motors so as to facilitate control and speed regulation.

The pressure port P of the lower cylinder chamber hydraulic valve 20 is also communicated with the control port X of the upper cylinder chamber hydraulic valve 23, and the port a of the lower cylinder chamber hydraulic valve 20 is also communicated with the control port X of the upper cylinder chamber hydraulic valve 23 through the first restrictor 21. The pressure port P of the upper cylinder chamber hydraulic valve 23 is communicated with the control port X of the lower cylinder chamber hydraulic valve 20, and the port a of the upper cylinder chamber hydraulic valve 23 is communicated with the control port X of the lower cylinder chamber hydraulic valve 20 through the second restrictor 22. The first throttle 21 and the second throttle 22 are both a general fixed throttle.

The overflow protection oil paths of the lower cylinder cavity oil pump 18, the upper cylinder cavity oil pump 25, the lower cylinder cavity of the hydraulic cylinder 1 and the upper cylinder cavity comprise corresponding one-way valves and overflow valves communicated with the one-way valves, and the overflow protection oil paths adopt common protection oil paths, so that the overflow protection oil paths are not shown in fig. 1.

When the hammer is driven, the hammer core 13 and the piston rod connected with the hammer core perform up-and-down reciprocating motion along with the alternate work of the lower cylinder cavity oil pump 18 and the upper cylinder cavity oil pump 25 so as to complete the pile driving and sinking of the foundation pile. Firstly, the lower cylinder cavity oil pump 18 is started, the lower cylinder cavity hydraulic valve 20 is in the position shown in fig. 2, the port A and the port P are communicated, the upper cylinder cavity oil pump 25 is in a shutdown state, pressure oil at the oil outlet of the lower cylinder cavity oil pump 18 flows to the lower cylinder cavity oil port 2 through the port P and the port A of the lower cylinder cavity oil pump 18, and the pressure oil flowing through the lower cylinder cavity oil port 2 enters the lower cavity of the hydraulic cylinder to push the piston rod 7 and the hammer core 13 to move upwards so as to complete hammer lifting. At the same time, the lower cylinder chamber oil pump 18 also flows into the control X of the upper cylinder chamber hydraulic valve 23 to push the sliding core to move to another position shown in fig. 2, so that the port a and the port T of the upper cylinder chamber hydraulic valve 23 are communicated, and the hydraulic oil in the upper cylinder chamber of the hydraulic cylinder 1 returns to the oil tank 26.

When the hammer core 13 reaches the set upper position, the lower cylinder cavity oil pump 18 is closed, the upper cylinder cavity oil pump 25 is started, and at the moment, the valve core of the lower cylinder cavity hydraulic valve 20 is still at the position shown in fig. 2, namely, the port P and the port A of the lower cylinder cavity hydraulic valve 20 are still in a communicated state, and the port A and the port T are disconnected; the ports P and a of the upper chamber hydraulic valve 23 are in a disconnected state, and the port a is communicated with the port T. The pressure oil pumped by the upper cylinder cavity oil pump 25 is firstly pumped into the control oil port X of the lower cylinder cavity hydraulic valve 20 and the A port and the T port of the upper cylinder cavity hydraulic valve 23, due to the arrangement of the second throttle valve 22 in the control oil path, pressure difference is formed at two ends of the second throttle valve 22, the pressure difference pushes the sliding core of the lower cylinder cavity hydraulic valve 20 to move to the other end position, the A port and the T port of the lower cylinder cavity hydraulic valve 20 are communicated, the pressure oil in the lower cylinder cavity returns to the oil tank 26, meanwhile, the pressure oil in the control cavity of the upper cylinder cavity hydraulic valve 23 is released through the first throttle valve 21 and the A port and the T port of the lower cylinder cavity hydraulic valve 20, the sliding core of the upper cylinder cavity hydraulic valve 23 moves to the other end position, the P port and the A port of the upper cylinder cavity hydraulic valve 23 are communicated, and the hammer core oil pump 13 hammers under the pressure oil and gravity action of the upper.

The lower chamber oil pump 18 is then started again, at which time the port a of the lower chamber hydraulic valve 20 remains disconnected from the port P and is connected to the port T, and the port a of the upper chamber hydraulic valve 23 remains connected to the port P and is disconnected from the port T. The pressure oil of the lower cylinder cavity oil pump 18 firstly enters the control oil port X of the upper cylinder cavity hydraulic valve 23 and the port A and the port T of the lower cylinder cavity hydraulic valve 20, meanwhile, due to the arrangement of the first throttle valve 21, pressure difference is formed at two ends of the first throttle valve 21, the pressure difference pushes the sliding core of the upper cylinder cavity hydraulic valve 23 to move to another position, the port A of the upper cylinder cavity hydraulic valve 23 is communicated with the port T, the pressure oil of the upper cylinder cavity of the hydraulic cylinder 1 returns to the oil tank 26, meanwhile, the pressure oil of the control cavity of the lower cylinder cavity hydraulic valve 20 passes through the second throttle valve 22 and the port A and the port T of the upper cylinder cavity hydraulic valve 23, the sliding core of the lower cylinder cavity hydraulic valve 20 moves to the other end position, the port P and the port A of the lower cylinder cavity hydraulic valve 20 are communicated, and the pressure oil pumped out by the lower cylinder cavity oil pump 18 enters the lower cylinder cavity of the hydraulic cylinder 1 again to. The above steps are repeated to realize the lifting and dropping of the pile hammer.

Fig. 3 shows another embodiment of the present invention, which is the same as the above embodiment except that the structures of the hydraulic cylinder 1 and the hammer core guide 10 are different from those of the above embodiment. In this embodiment, the hydraulic cylinder 1 is a double-rod piston type hydraulic cylinder, the hammer core guide 10 is two guide rods parallel to each other, and the hammer core 13 is slidably supported on the two guide rods parallel to each other, but the guide rods may be three or four guide rods parallel to each other.