CN108644083B - A kind of ultrahigh pressure axial plunger pump of two-stage pressure output - Google Patents

Abstract

The invention discloses an ultra-high pressure axial plunger pump with two-stage pressure output. The main components are a transmission shaft, a flow distribution plate, a cylinder body, a plunger, a sliding shoe, a return plate, a swash plate, a casing and the like. There are two rows of plunger cavities on the cylinder body, and the inner and outer ring plungers are respectively installed in the cylinder body and the outer two rows of evenly distributed plunger cavities. One side of the distribution plate is matched with the distribution end surface of the cylinder body, and the other side is fixed with the rear housing through positioning pins. Four waist-shaped notch flow channels are arranged on the distribution plate. The rear housing is provided with outer ring oil inlet passage, inner ring oil inlet passage, outer ring oil outlet passage, and inner ring oil outlet passage, and the four oil passages are respectively connected with four waist-shaped notch flow passages on the distribution plate. Through the design of the oil circuit on the rear casing, including the installation of sequence valves and check valves, the present invention can achieve the following functions: when the system pressure is lower than the first-stage pressure, it can be used as a double-row axial piston pump. When the system pressure is higher than the primary pressure, it is used as a self-boosting ultra-high pressure axial piston pump, which doubles the pressure level of the pump to achieve the purpose of ultra-high pressure.

Description

A Two-Stage Pressure Output Ultrahigh Pressure Axial Piston Pump

technical field

The invention relates to a novel axial plunger pump, in particular to an ultra-high pressure axial plunger pump with two-stage pressure output.

Background technique

Axial piston pumps are important power components in hydraulic systems, widely used in the fields of industrial hydraulics and travel hydraulics, and are one of the most widely used hydraulic components in modern hydraulic components. In addition, due to the complex structure of the axial piston pump, the requirements for the manufacturing process and materials are very high, so it is one of the hydraulic components with high technical content. In recent years, with the development of materials, manufacturing, electronics and other technologies, new technologies for axial piston pumps have emerged in an endless stream.

When the working pressure of the hydraulic system exceeds 32MPa, it is usually called ultra-high pressure hydraulic pressure. In the field of modern science and technology and industrial production, the application of ultra-high pressure hydraulic technology has become more and more extensive. At present, factors such as the structure of the axial piston pump and the strength and stiffness of the main components affect the displacement and output pressure of the pump. Therefore, it is of great significance to study the structural form of the plunger pump to improve the displacement and working pressure of the axial plunger pump.

Contents of the invention

The technical problem to be solved by the present invention is to provide an ultra-high pressure axial plunger pump with two-stage pressure output. The characteristic of the axial plunger pump is to realize two-stage pressure output.

In order to solve the above-mentioned technical problems, the present invention is achieved through the following technical solutions:

A two-stage pressure output ultra-high pressure axial piston pump, including a main shaft, a valve plate, a cylinder body, a plunger including an inner ring plunger and an outer ring plunger, a sliding shoe including an inner sliding shoe and an outer sliding shoe, and a return plate , swash plate, housing and rear housing; the rear housing is installed and fixed on the right end of the housing, the left side of the main shaft is installed on the left end of the housing through the retaining ring for the shaft, the rolling bearing and the retaining ring for the hole, and the right side of the main shaft is passed through The shaft sleeve and oil-free lubricating bearing are installed in the blind hole of the rear housing; the cylinder is installed on the main shaft in the inner cavity of the housing, and the main shaft transmits power to the cylinder through splines to make the cylinder rotate;

The cylinder body is provided with 2n plunger cavities that are staggered and evenly distributed around the axis of the cylinder body, including n inner ring plunger cavities and n outer ring plunger cavities, and each inner ring plunger cavity is provided with a first flow channel leading to Outside the cylinder, each outer plunger cavity is provided with a second flow channel leading to the cylinder; n inner plungers and n outer plungers are respectively installed in the inner plunger cavity and the outer plunger cavity of the cylinder. In the plunger cavity of the inner ring; the head of each inner ring plunger is equipped with an inner sliding shoe, and an oil chamber is opened on the bottom surface of the inner sliding shoe, and the pressure oil in the plunger pump is introduced into it, so that the pressure oil from the inner ring plunger cavity The thrust of the thrust is balanced with the oil pressure in the oil chamber; the head of each outer ring plunger is equipped with an outer shoe, and the bottom surface of the outer shoe is opened with an oil chamber, and the pressure oil in the plunger pump is introduced into it, Balance the thrust from the plunger chamber of the outer ring with the oil pressure in the oil chamber; the swash plate is installed and fixed on the left end surface of the inner cavity of the housing, and the surface of the swash plate and the sliding shoe has an inclination angle relative to the cylinder axis ; The plunger pump uses the swash plate to push the inner ring plunger and the outer ring plunger to forcibly retract during the oil pressure process, and relies on the return mechanism to make the inner ring plunger and the outer ring plunger stretch out during the oil suction process; the return stroke The mechanism includes a disc spring, an adjustment pad, a ball bowl and a return plate. The center hole of the return plate is matched with the spherical surface of the ball bowl. The inner sliding shoe and the outer sliding shoe are respectively inserted into the evenly distributed circular holes on the return plate; the disc spring The ball bowl is pressed to the return plate through the adjusting pad, and then the return plate is attached to the swash plate, and the return plate forces the bottom of the inner and outer shoes to always move against the surface of the swash plate, and then passes through the inner and outer shoes Force the inner ring plunger and outer ring plunger to return; when the cylinder drives the inner ring plunger and outer ring plunger to rotate, the inner ring plunger and outer ring plunger Linear reciprocating motion inside;

The distribution plate is equipped with four waist-shaped windows, which are the first and second oil-absorbing waist-shaped windows and the first and second oil-row waist-shaped windows; the central spring is set on the main shaft in the shaft hole of the cylinder body, and the cylinder body is fixed by a gasket. Press against the distribution plate, so that one side of the distribution plate is closely attached to the distribution end surface of the cylinder body, and slides relatively; while the other side of the flow distribution plate is fixed on the end surface of the rear housing by positioning pins; the first oil-absorbing waist The window and the first oil row waist window are on the circular track of the first flow channel in the inner plunger chamber of the cylinder body, and the second oil suction waist window and the second oil discharge waist window are in the outer plunger chamber of the cylinder body On the circular track of the second runner rotation;

In the lower half of the rear shell, there is a first waist-shaped notch flow channel as the inner ring oil inlet, and the second waist-shaped notch flow channel is used as the outer ring oil inlet; in the upper half of the rear shell, there is a third The waist-shaped slot flow channel is used as the inner ring oil outlet, and the fourth waist-shaped slot flow channel is used as the outer ring oil outlet; the first waist-shaped slot flow channel and the third waist-shaped slot flow channel are respectively connected to the valve plate The first oil-absorbing waist-shaped window and the first oil-discharging waist-shaped window are connected, and the second waist-shaped notch flow channel and the fourth waist-shaped notch flow channel are respectively connected with the second oil-suction waist-shaped window and the second oil-absorbing window on the distribution plate. The waist-shaped window for oil discharge is connected; the second waist-shaped notch flow channel is connected to the oil tank as the oil inlet channel of the outer ring; the fourth waist-shaped notch flow channel is used as the oil outlet channel of the outer ring to connect to the working system through the second sequence valve; One waist-shaped notch flow channel is used as the oil inlet passage of the inner ring, and a check valve is installed in the flow channel, and the oil supply system is connected externally; the third waist-shaped notch flow channel is used as the oil outlet passage of the inner ring to connect with the working system; Two oil ports are opened at the bottom of the casing, the first waist-shaped notch flow channel communicates with the fourth waist-shaped notch flow channel, and a first sequence valve is installed between the two flow channels.

The invention relates to an ultra-high pressure axial plunger pump with two-stage pressure output. The first sequence valve is opened at high pressure and closed at low pressure; the second sequence valve is opened at low pressure and closed at high pressure. When the system pressure is lower than the first-stage pressure, the oil in the outlet circuit of the outer ring can only enter the working system directly through the second sequence valve because the pressure is lower than the opening pressure of the first sequence valve; when the system pressure is higher than the first-stage When pressure is high, the second sequence valve is closed under high pressure, and the pressure oil from the oil outlet of the outer ring enters the oil inlet of the inner ring through the first sequence valve for secondary pressurization.

In the above-mentioned new axial plunger pump, when the pressure of the working system is lower than the primary pressure, the oil from the oil outlet of the outer ring directly enters the working system. The oil supply system supplies oil to the oil inlet passage of the inner ring. After the inner ring plunger cavity is pressurized, it enters the working system through the oil outlet of the inner ring.

Due to the adoption of the above technical solution, the present invention provides a two-stage pressure output ultra-high pressure axial piston pump, which has the following beneficial effects compared with the prior art:

The plunger pump of the present invention can realize two-stage pressure output, and is not only suitable for low-pressure and large-displacement working conditions, but also suitable for ultra-high-pressure working conditions. When the working system pressure is lower than the primary pressure, the present invention is used as a double-row axial piston pump, which is equivalent to two axial piston pumps connected in parallel to supply oil to the working system; when the working system pressure is higher than When the first-stage pressure is used, the present invention is used as a self-boosting ultra-high pressure axial plunger pump, and its internal oil circuits are connected in series to double the pressure level of the pump.

Description of drawings

Fig. 1 is a three-dimensional schematic diagram of an ultra-high pressure axial piston pump with two-stage pressure output according to the present invention;

Fig. 2 is a schematic diagram of the main shaft side of an ultra-high pressure axial piston pump with two-stage pressure output according to the present invention;

Fig. 3 is the sectional view of line A-A among Fig. 2;

Fig. 4 is the sectional view of B-B line among Fig. 2;

Figure 5 is an enlarged view of the return mechanism;

In Fig. 6: (a) is a schematic diagram of the distribution end face of the rear housing, (b) is a sectional view of line A-A in (a), and (c) is a schematic diagram of the distribution of the plunger cavity on the cylinder body of the present invention;

Fig. 7 is a schematic diagram of a distribution plate;

In Fig. 8: (a) is a schematic diagram of the oil inlet of the outer ring of the rear casing, (b) is a schematic diagram of the distribution end surface of the rear casing of the present invention, (c) is a schematic diagram of the oil circuit of the rear casing of the present invention, and (d) is a schematic diagram of the rear casing of the present invention. The schematic diagram of the bottom end face of the housing, (e) is the schematic diagram of the oil outlet of the inner ring of the rear housing of the present invention, (f) is the schematic diagram of the oil outlet of the outer ring of the rear housing of the present invention, (g) is the schematic diagram of the oil circuit of the rear housing of the present invention, ( h) is a schematic diagram of the oil inlet of the inner ring of the rear shell of the present invention;

In Fig. 9: (a) is a schematic diagram of the oil circuit of the rear casing of the present invention, and (b) is a schematic diagram of the oil circuit of the rear casing of the present invention.

In the figure: 1-main shaft, 2-skeleton oil seal, 3-retaining ring for hole, 4-pin, 5-housing, 6-swash plate, 7-adjusting pad, 8-disc spring, 9-return plate, 10 - Inner ring plunger, 11 - Cylinder body, 12 - Pin, 13 - O-ring, 14 - Rear housing, 15 - O ring, 16 - Spring washer, 17 - Screw, 18 - Bushing, 19 - None Oil lubricated bearing, 20-distribution plate, 21-hole retaining ring, 22-washer, 23-spring, 24-outer ring plunger, 25-ball bowl, 26-outer sliding shoe, 27-inner sliding shoe, 28- Shaft retaining ring, 29-rolling bearing, 111-inner ring plunger cavity, 112-outer ring plunger cavity, 113-first flow channel, 114-second flow channel, 201-second oil suction waist window (outer ring oil suction Waist-shaped window), 202-first oil-absorbing waist-shaped window (inner ring oil-absorbing waist-shaped window), 203-first oil-discharging waist-shaped window (inner ring oil-discharging waist-shaped window), 204-second oil-discharging waist-shaped window (outer ring oil discharge waist window), 141-second waist-shaped slot runner (outer ring oil inlet), 142-first waist-shaped slot runner (inner ring oil inlet), 143-third Waist-shaped notch flow channel (inner ring oil outlet), 144 - fourth waist-shaped notch flow channel (outer ring oil outlet), 301 - one-way valve, 302 - first sequence valve, 303 - second sequence valve.

Detailed ways

Below in conjunction with accompanying drawing and specific embodiment the present invention is described in further detail:

In order to further explain the technical means and effects adopted by the present invention to achieve the intended purpose of the invention, the specific implementation, features and effects of a new type of axial piston pump proposed according to the present invention will be described in detail below in conjunction with the accompanying drawings. as follows.

An ultra-high pressure axial piston pump with two-stage pressure output of the present invention, as shown in Figures 1 to 5, includes a main shaft 1, a flow distribution plate 20, a cylinder body 11, a plunger, a sliding shoe, a return plate 9, and a swash plate 6. Housing 5 and rear housing 14; the plunger includes an inner ring plunger 10 and an outer ring plunger 24; the sliding shoe includes an inner sliding shoe 27 and an outer sliding shoe 26; the rear housing 14 is installed by screws It is fixed on the right end of the housing 5, the left side of the main shaft 1 is installed on the left end of the housing 5 through the retaining ring 28 for the shaft, the rolling bearing 29 and the retaining ring 3 for the hole, and the right side of the main shaft 1 is installed through the shaft sleeve 18 and the oil-free lubricating bearing 19 is installed in the blind hole of the rear housing 14; the cylinder 11 is installed on the main shaft 1 in the inner cavity of the housing 5, and the main shaft 1 transmits power to the cylinder 11 through the spline, so that the cylinder 11 rotates;

As shown in Fig. 4 and (b) and (c) in Fig. 6, the cylinder body 11 is provided with ten plunger cavities staggered and evenly distributed around the axis of the cylinder body, including five inner plunger cavities 111 and five outer plunger cavities. In the plunger cavity 112 of the ring; each inner plunger cavity 111 is provided with a first flow channel 113 leading to the outside of the cylinder body 11, and each outer ring plunger cavity 112 is provided with a second flow channel 114 leading to the cylinder body 11 Outside; five inner ring plungers 10 and five outer ring plungers 24 are respectively installed in the inner ring plunger cavity 111 and the outer ring plunger cavity 112 of the cylinder body 11; the head of each inner ring plunger 10 is installed There is an inner sliding shoe 27, and an oil chamber is opened on the bottom surface of the inner sliding shoe 27, and the pressure oil in the plunger pump is introduced into it, so that the thrust from the inner ring plunger cavity is balanced with the oil pressure in the oil chamber; The head of each outer ring plunger 24 is equipped with an outer sliding shoe 26, and the bottom surface of the outer sliding shoe 26 has an oil chamber, and the pressure oil in the plunger pump is introduced into it, so that the thrust from the outer ring plunger chamber and the thrust of the outer ring plunger cavity are combined with the oil chamber. The oil pressure in the oil chamber is balanced; the swash plate 6 is installed and fixed on the left end surface of the inner cavity of the housing 5 through the positioning pin 4, and the surface of the swash plate 6 and the sliding shoe has an inclination angle relative to the axis of the cylinder body 11; The above-mentioned plunger pump pushes the inner ring plunger 10 and the outer ring plunger 24 to forcibly retract by means of the swash plate 6 during the oil pressure process, and makes the inner ring plunger 10 and the outer ring plunger 24 stretch out by means of the return mechanism during the oil suction process. The return mechanism, as shown in Fig. 3, Fig. 4 and Fig. 5, comprises a disc spring 8, an adjustment pad 7, a ball bowl 25 and a return plate 9, and the center hole of the return plate 9 cooperates with the spherical surface of the ball bowl 25, and the inner The sliding shoe 27 and the outer sliding shoe 26 are respectively inserted into the evenly distributed circular holes on the return plate 9; the disc spring 8 presses the ball bowl 25 to the return plate 9 through the adjustment pad 7, and then makes the return plate 9 stick to the swash plate 6. The return plate 9 forces the bottom of the inner slide shoe 27 and the outer slide shoe 26 to always move against the surface of the swash plate 6, and then forces the inner ring plunger 10 and the outer ring plunger 24 through the inner slide shoe 27 and the outer slide shoe 26 Return stroke: when the cylinder drives the inner ring plunger 10 and the outer ring plunger 24 to rotate, the inner ring plunger 10 and the outer ring plunger 24 reciprocate linearly in the inner ring plunger cavity 111 and the outer ring plunger cavity 112 respectively Movement; as shown in Figure 7, the valve plate 20 is provided with four waist-shaped windows, which are respectively the first and second oil-absorbing waist-shaped windows 202 and 201 and the first and second oil-discharging waist-shaped windows 203 and 204; as shown in Figure 4 As shown, the central spring 23 is sleeved on the main shaft 1 in the shaft hole of the cylinder body 11, and the cylinder body 11 is pressed to the distribution plate 20 through the washer 22, so that one side of the flow distribution plate 20 and the distribution end surface of the cylinder body 11 are closely attached, and Relatively sliding; on the other side of the distribution plate 20, fixed on the end face of the rear housing 14 by the positioning pin 12; On the circular trajectory of the rotation of the first flow channel 113 of the plunger chamber 111, the circular trajectory of the rotation of the second oil suction waist window 201 and the second oil discharge waist window 204 in the outer ring of the cylinder 11 of the plunger cavity 112 and the second flow channel 114 superior;

As shown in (a) and (b) in Figure 9, a first waist-shaped notch flow passage 142 is provided as an inner ring oil inlet passage in the lower half of the rear housing 14, and the second waist-shaped notch flow passage 141 As an oil inlet passage for the outer ring; on the upper half of the rear housing 14, a third waist-shaped notch flow passage 143 is provided as an oil outlet passage for the inner ring, and a fourth waist-shaped notch flow passage 144 is used as an oil outlet passage for the outer ring; One waist-shaped notch flow channel 142 and the third waist-shaped notch flow channel 143 communicate with the first oil-absorbing waist-shaped window 202 and the first oil-discharging waist-shaped window 203 on the distribution plate 20 respectively, and the second waist-shaped notch The flow channel 141 and the fourth waist-shaped notch flow channel 144 communicate with the second oil-absorbing waist-shaped window 201 and the second oil-discharging waist-shaped window 204 on the distribution plate 20 respectively; the second waist-shaped notch flow channel 141 serves as the outer The ring inlet oil passage is connected to the fuel tank; the fourth waist-shaped notch flow passage 144 is used as the outer ring oil outlet passage and connected to the working system through the second sequence valve 303; the first waist-shaped notch flow passage 142 is used as the inner ring oil inlet passage, and its A one-way valve 301 is installed in the flow channel, which is externally connected to the oil supply system; the third waist-shaped notch flow channel 143 is used as the inner ring oil outlet to connect with the working system; two oil ports are opened at the bottom of the rear housing 14, and the first waist The waist-shaped notch channel 142 communicates with the fourth waist-shaped notch channel 144, and a first sequence valve 302 is installed between the two channels.

When the pressure of the working system is lower than the primary pressure, as shown in Figure 6, the oil supply system supplies oil to the plunger cavity of the inner ring of the pump. Driven by the main shaft, the cylinder body starts to rotate, and the volume of the two rows of plunger chambers on the oil suction side continues to expand. During this process, the outer ring plunger chambers suck oil from the oil tank, and the inner ring plunger chambers are supplied with oil by the oil replenishment system. As the cylinder continues to rotate, the plunger begins to retract under the constraint of the swash plate, the volume of the inner and outer plunger chambers decreases continuously, and the pressure oil generated by the outer plunger chamber enters the working system through the oil outlet of the outer ring , and the pressure oil generated by the plunger cavity of the inner ring enters the working system through the oil outlet of the inner ring.

During this process, the oil pressure is lower than the primary pressure, the first sequence valve is always closed, and the second sequence valve is open. At this time, the present invention is used as a double-row axial piston pump, which is equivalent to two axial piston pumps connected in parallel to supply oil to the working system.

When the pressure required by the working system is higher than the primary pressure, the oil supply system stops supplying oil to the plunger cavity of the inner ring. After the new axial piston pump is started, the oil enters the plunger cavity of the outer ring from the oil tank. After the first stage of pressurization, the pressure oil enters the plunger cavity of the inner ring through the first sequence valve. The high-pressure oil enters the working system through the oil outlet of the inner ring.

During this process, the second sequence valve is closed under high pressure, and the primary pressure oil cannot enter the working system; the first sequence valve is opened under the action of the primary pressure oil. In this case, the present invention is used as a self-boosting ultra-high pressure axial plunger pump, and its internal oil circuit is connected in series to change the pressure of the output oil and double the pressure level of the plunger pump to To achieve the purpose of ultra-high pressure.

①The path of the hydraulic oil when the present invention works in the double-row axial piston pump state is:

Fuel tank→oil inlet circuit of outer ring→piston cavity of outer ring→oil outlet circuit of outer ring→second sequence valve→working system;

Supplement oil system→check valve→inner ring oil inlet passage→inner ring plunger chamber→inner ring oil outlet passage→working system.

②The path of the hydraulic oil when the present invention works in the state of the self-pressurized ultra-high pressure axial piston pump is:

Fuel tank→Oil inlet passage of outer ring→Plunger chamber of outer ring→First sequence valve→Plunger chamber of inner ring→Oil outlet passage of inner ring→Working system.

Claims (1)

1. a kind of ultrahigh pressure axial plunger pump of two-stage pressure output, it is characterised in that: including main shaft, valve plate, cylinder body, plunger It include interior piston shoes and outer piston shoes, return plate, swash plate, shell and back casing including inner ring plunger and outer ring plunger, piston shoes；Rear shell Body is fixed on the right end of shell, and the left side of main shaft is mounted on shell with retaining ring by shaft block ring, rolling bearing and hole The right side of left end, main shaft is mounted in the blind hole of back casing by axle sleeve and Nonlubricated bearing；Cylinder body is mounted on housing cavity Main shaft on, main shaft imparts power to cylinder body by spline, rotates cylinder body；

It includes n inner ring plunger cavity and n outer ring plunger that cylinder body, which is equipped with around the 2n plunger cavity that cylinder body axis is uniform staggered with, Chamber, the interior first runner that is equipped with of each inner ring plunger cavity lead to outside cylinder body, second flow channel are equipped in each outer ring plunger cavity and leads to cylinder In vitro；N inner ring plunger and n outer ring plunger are separately mounted in the inner ring plunger cavity and outer ring plunger cavity of cylinder body；In each The head of loop pillar plug is equipped with interior piston shoes, and interior piston shoes bottom surface is provided with grease chamber, and the pressure oil in the plunger pump is introduced wherein, is made Thrust from inner ring plunger cavity balances each other with the oil pressure in the grease chamber；The head of each outer ring plunger is equipped with outer piston shoes, outside Piston shoes bottom surface is provided with grease chamber, and the pressure oil in the plunger pump is introduced to the thrust and the oil wherein made from outer ring plunger cavity Oil pressure in room balances each other；Swash plate is fixed on the left side of housing cavity, swash plate and piston shoes cooperation surface relative to Cylinder body axis has an inclination angle；The plunger pump pushes inner ring plunger and outer ring plunger to force during pressure oil by swash plate It retracts, keeps inner ring plunger and outer ring plunger overhanging by return mechanism in oil-absorbing process；The return mechanism includes dish-shaped bullet Spring, adjusting pad, ball bowl and return plate, backhaul center hole and ball bowl spherical cooperate, and interior piston shoes and outer piston shoes are respectively inserted in back On journey disk in equally distributed round hole；Ball bowl is pressed to return plate by adjusting pad by disk spring, and then is affixed to return plate Swash plate, return plate forces apparent motion of the bottom of interior piston shoes and outer piston shoes always close to swash plate, then passes through interior piston shoes and outer cunning Boots force inner ring plunger and outer ring plunger backhaul；When cylinder body drives inner ring plunger and outer ring plunger to rotate, inner ring plunger and outer Loop pillar plug encloses in plunger cavity and outer ring plunger cavity inside respectively makees straight reciprocating motion；

Valve plate is set there are four kidney-shaped window, respectively the first and second oil suction kidney-shaped window and the first and second oil extraction kidney-shaped window； Central spring is sleeved on main shaft in axle hole of cylinder block, and cylinder body is pressed to valve plate by washer, make valve plate side and Cylinder body flow end face fits closely, and opposite sliding；And in the other side of valve plate, back casing is fixed on by positioning pin On end face；The circumference that first oil suction kidney-shaped window and the first oil extraction kidney-shaped window are rotated in the inner ring plunger cavity first runner of cylinder body On track, circumference that the second oil suction kidney-shaped window and the second oil extraction kidney-shaped window are rotated in the outer ring plunger cavity second flow channel of cylinder body On track；

The first kidney-shaped notch runner is equipped with as inner ring in-line in the lower half of back casing, and the second kidney-shaped notch runner is as outer Enclose in-line；Third kidney-shaped notch runner is equipped with as inner ring vent line, the 4th kidney-shaped notch runner in the upper half of back casing As outer ring vent line；First kidney-shaped notch runner and third kidney-shaped notch runner respectively with the first oil suction kidney-shaped on valve plate Window and the first oil extraction kidney-shaped window are connected, and the second kidney-shaped notch runner and the 4th kidney-shaped notch runner are respectively and on valve plate The second oil suction kidney-shaped window and the second oil extraction kidney-shaped window be connected；Second kidney-shaped notch runner is connected as outer ring in-line Fuel tank；4th kidney-shaped notch runner connects work system by the second sequence valve as outer ring vent line；First kidney-shaped notch runner As inner ring in-line, check valve, external oil-supplementing system are installed in runner；Third kidney-shaped notch runner is fuel-displaced as inner ring Road connects with work system；Two hydraulic fluid ports, the first kidney-shaped notch runner and the 4th kidney-shaped notch runner phase are opened in back casing bottom Connection, and the first sequence valve is installed between the two runners；First sequence valve is high pressure opening, and low pressure is closed；Second is suitable Sequence valve is low pressure opening, and high pressure is closed；When system pressure is lower than first class pressure, the oil liquid of outer ring vent line is lower than due to pressure The cracking pressure of first sequence valve can only be directly entered work system by the second sequence valve；When system pressure is higher than level-one pressure When power, the second sequence valve is closed under high pressure, and the pressure oil of outer ring vent line enters inner ring in-line by the first sequence valve, into Row secondary pressurized.