CN1101700A - High pressure radial plunger oil pump - Google Patents

Abstract

It is composed of the pump casing, main shaft, pumping mechanism and oil distributing mechanism. The pump operation mechanism is composed of two sets of high and low pressure composite plunger with rollers provided at two ends of the low pressure plunger, and two sets of hyperbolic internal cam, arranged at 90 degrees to each other, for oil output in turns in cooperation with the rollers. Said oil distributing mechanism has two sets, one high pressure and the other low pressure, and the low pressure mechanism is composed of the pump block, low pressure oil passage of liner, distributor, distributing shaft and its external ring, and the high pressure mechanism is composed of the high pressure oil passage in the pump block and liner, distributing disk and end cap.

Description

High pressure radial plunger oil pump

The present invention relates to a kind of high pressure oil pump that is used for hydraulic machine, particularly a kind of novel high-pressure radial plunger oil pump.

High pressure oil pump commonly used in the Machinery Tool Hydraulic Transmission at present is except that gear type, blade type and gerotor pump, and the most frequently used is the axial piston oil pump.The shortcoming of present axial piston oil pump is: on the one hand, in order to satisfy two kinds of operating modes of the high-speed and load low speed of hydraulic machine idle stroke simultaneously, so must adopt big flow oil pump to satisfy the load usage requirement to small flow from satisfying the high-speed big Flow-rate adjustment of idle stroke.Therefore, not only cause energy loss, and make the oil pump volume bigger; Supporting with it motor also must be selected corresponding power by the requirement of the big pressure of big flow, thereby volume is also corresponding big, makes troubles to installation owing to take up space big; On the other hand, structurally, more easy to wear under the effect that is subjected to axial force because the oil distributor diameter is bigger; Because plunger end adopts the piston shoes structure, cooperating with the pump housing is sliding friction, and the long-term back of using is easy to wear; The suffered lateral force of movement parts in the pump housing is very big, so that have influence on part working life, for example aggravate the wearing and tearing of described piston shoes and easily it come off, if just wherein any comes off and can cause whole pump to damage, oil distribution casing and cylinder body are worn and torn simultaneously and plunger stuck; Aspect again, complex structure, component are many and requirement on machining accuracy is high, and for example the spheroid of described piston shoes need and need to grind with special purpose machine tool and clamping apparatus processing, the processing and the assembling difficulty of the servo variable mechanism parts of oil pump are very big, thereby quality control is than difficulty and processing cost height.

Except that above-mentioned, other has a kind of radial plunger pump, arrange because its plunger all is a radial radiation-type, so profile is very big, and structure is outmoded, work is reliable inadequately, can not satisfy big flow, big pressure requirement, and it is superseded to have become.

In order to overcome the above-mentioned shortcoming of existing all kinds of plunger pumps, the purpose of this invention is to provide and a kind ofly can satisfy big flow low-pressure and two kinds of operating modes of small flow high pressure and volume is little, simple and compact for structure, the life-span is long, cost is low a kind of novel radial plunger high pressure oil pump simultaneously.

A kind of high-pressure radial formula plunger-type fuel pump of the present invention, it comprises: an oil pump case; One bearing support that is spirally connected with described oil pump case front end, in establish before and after radial bearing and the plain thrust bearing between them; One working spindle is bearing on described each bearing; Be located at oil sealing and pump oil operation mechanism on each matching trim of oil pump, oil distribution mechanism; It is characterized in that, the oily operation mechanism of described pump comprises a rotation pump housing, it is arranged in the described oil pump case, its front end sets firmly a drive plate, described drive plate is connected with key with rear-end of spindle and is bearing on the radial bearing of back, its rear end is fixed an oil distributing shaft and is bearing on its outer shroud (lining), so that the described pump housing can rotate with described main shaft around the housing central axis, is provided with two parallel to each other and perpendicular to the identical cylinder hole of described central axis in the described pump housing; Two high-voltage oil cylinders cover is located at the intermediate portion in described respective cylinder hole respectively so that each cylinder hole is divided into two cylinders up and down; Two groups of high low pressure combined plunger branches are located in the described upper and lower cylinder, and described plunger end is installed a roller respectively; Two hyperbola convex wheel bodys are located on the axial central position of each oil har opening respectively and are mutually 90 ° of ground by its protruding peak and are fixed on the housing, so that when the pump housing rotates together with oil cylinder, by the rotating inertia force of each plunger make roller rest on cam race upper edge cam profile reciprocating to realize high and low pressure plunger work so that fuel feeding alternately continuously; Described oil distribution mechanism comprises low pressure oil oil distribution mechanism and high pressure oil oil distribution mechanism, described low pressure oil oil distribution mechanism by the low pressure oil duct in the pump housing and the cylinder sleeve, be arranged on the oil distributing member between pump case and end cap, be arranged on the oil distributing shaft in the oil distributing member inner chamber and the outer shroud of oil distributing shaft and form, described oil distributing member is provided with low pressure oil and imports and exports; Described high pressure oil oil distribution mechanism by the high-pressure oil duct in the pump housing and the cylinder sleeve, oil distributing shaft and be arranged on oil distributing shaft and end cap between and form with the high pressure oil distribution casing that end cap sets firmly, described end cap is provided with the high pressure oil oil road.

The molded lines of described hyperbola convex wheel body is to be made up of with the circular arc portion such as grade the symmetrically arranged Archimedes spiral that lift peak portion and following Cheng Gu portion form, 180 ° of scopes of each cam ring molded lines comprise: from paddy portion to peak portion is 90 °, peak portion scope is 5 ° and waits circular arc, so that form a to-and-fro motion of plunger.

Also be provided with compensation hydraulic mechanism, it comprises the internal oil channel that is arranged on compensation oilhole, oil distributing shaft and the pump housing in the described oil distribution casing and the balance oil pocket between pump housing front end and spindle nose, and is arranged on a balance spring and spring seat in the oil pocket; Bear so that the oil distribution casing Transverse plane is subjected to constant less end thrust the axial force of high-pressure and hydraulic compensation oil and spring support force with joint efforts by the plane bearing of main shaft.

The described pump housing is provided with four cantilever arms symmetrically corresponding to the upper and lower and left and right of periphery of each central position, cylinder hole, so that the pump housing rotation time all can be born plunger in 360 ° of scopes lateral force, to improve the force-bearing situation of roller engagement rolling.

Now by a most preferred embodiment of the present invention and in conjunction with its accompanying drawing to further specify purpose of the present invention, characteristics and advantage.

Fig. 1 is the longitudinal sectional view along its central axis of a high-pressure radial plunger pump of the present invention;

Fig. 2 is respectively along the amalgamation figure of two half sectional views of the A-A line of Fig. 1 and B-B line;

Fig. 3 is the sectional elevation along the C-C line of Fig. 1;

Fig. 4 is a STRUCTURE DECOMPOSITION schematic representation of the present invention;

Fig. 5 is the plan view of the rotation pump housing of the present invention;

Fig. 6 is the right elevation of Fig. 5;

Fig. 7 is the left view of Fig. 5;

Fig. 8 is the revolved sectional view along the A-A line of Fig. 6;

Fig. 9 is the vertical half sectional view that has partial sectional view of oil distributing shaft of the present invention;

Figure 10 is the right elevation of Fig. 9;

Figure 11 is the sectional elevation along the A-A line of Fig. 9;

Figure 12 is the sectional elevation along the B-B line of Fig. 9;

Figure 13 is the left view of Fig. 9;

Figure 14 is the sectional elevation along the C-C line of Fig. 9;

Figure 15 is the plane view of oil distribution casing of the present invention;

Figure 16 is the sectional view along the A-A line of Figure 15;

Figure 17 is a cam body longitudinal section of the present invention;

Figure 18 is the sectional elevation along the A-A line of Figure 17;

Figure 19 is a horizontal cross of oil distributing member of the present invention;

Figure 20 is that half sectional view is looked on the right side of Figure 19;

Figure 21 is the sectional view along the B-B line of Figure 19.

Be illustrated in figure 1 as a high-pressure radial plunger oil pump of the present invention, it comprises: oil pump case 12; Bearing support 1, it is connected with the front-end face of its seam with described housing 12 by screw, and its end face seal is by being embedded oil seal circle therebetween; Front and back bearings 25,35 is arranged in the stage shape seat hole of bearing support 1; Back-up ring 6 and plain thrust bearing 27 be arranged between front and back bearings the seat hole in, bearing cap 2 is bolted in the front end of bearing support 1; One main shaft 4, its front end journal rest is on described fore bearing 25, and its rear end is provided with endoporus 28, and a keyway is set on the periphery of rear end; One is located at the balanced controls in the endoporus 28, is formed by a balance spring 3 with in order to a spring seat 8 of support spring 3; One drive plate 24 is connected by the rear end of key 7 with described main shaft 4, and is bearing in the described rear bearing 35; The one rotation pump housing 14 is positioned at described pump case 12, and its front end is embedded between drive plate 24 and rear-end of spindle and with drive plate 24 and is spirally connected; Two cylinder sleeves 13 are separately positioned on the neutral position of cylinder bore, and the center line in two cylinder holes is positioned on the longitudinal median plane of the pump housing and respectively perpendicular to the central axis of the pump housing in parallel to each other; Two groups of roller plunger mechanism, be separately positioned on the two ends of cylinder sleeve 13, each group wherein comprises high-pressure plunger 10, low-pressure plunger 11 and roller 9, described high-pressure plunger 10 is embedded at the inner chamber of low-pressure plunger 11 fixing by jump ring 23, high-pressure plunger 11 sliding being assigned in the endoporus 29 of cylinder sleeve 13, described low-pressure plunger 12 sliding fitting in the cylinder hole 30 of the pump housing 14, described roller 9 is located on low-pressure plunger 11 ends, one side of low-pressure plunger 11 is provided with guiding groove 31, with be located on the pump housing, guider screw 32 on the corresponding cantilever arm 33 cooperates, so that when the pump housing 14 high speed rotating, whole roller plunger mechanism is pumped in the cylinder hole; Two convex wheel bodys 22, be fixedly connected on respectively in the described housing 12, (as shown in Figure 2, fix by screw 34 and housing) it is on the central position of respective cylinder body opening, wherein each comprises two symmetrically relative cam rings 33, the peak 34 of two cam bodies 22 is arranged to 90 ° mutually, and described roller is fitted on the interior raceway of cam 22; One oil distributing member 17 is fitted with the ear end face of described housing 12, is used to draw big flow low pressure oil; One end cap 20 is with described oil distributing member 17 terminations, in order to draw high pressure oil; One oil distributing shaft 18 is arranged in the described oil distributing member 17 by an oil distributing shaft outer shroud (lining) 16; One oil distribution casing 19 is arranged between described oil distributing shaft 18 and the end cap 20, is used to be communicated with high-pressure oil duct; Described end cap 20, oil distributing member 17 and housing 12 spiral shells knot one; Described oil distributing shaft spiral shell method is on the described pump housing 14.

Fig. 5 to Fig. 8 shows the concrete structure of the rotation pump housing 14, as shown in the figure, the pump housing 14 is provided with the two cylinder holes that are parallel to each other in vertical direction, in order to described cylinder sleeve 13 and roller plunger assembly to be set, requirement guarantees that cylinder centerline hole V is the rotating center axis of whole cylinder body perpendicular to the horizontal center line H(of cylinder body), the front end of cylinder body is established a round boss 34 in order to be embedded drive plate 24, and it is fixing with it with screw by the screw on the front-end face 35, the rear end of the pump housing is provided with circular-shaped, concave cavity 36 to match with oil distributing shaft 18, the pump housing on cylindrical periphery through the Transverse plane position of cylinder centerline hole V, about being respectively equipped with, four cantilever arms 33 of front and back symmetry, to cooperate with the middle circle arc groove 37 mutual unoccupied places of cam 22, so that simultaneously in pump housing rotation, the end thrust of bearing plunger by described cantilever arm 33, and guider screw 34(such as Fig. 2 and shown in Figure 7 be set in the screw on centrosymmetric two cantilever arms) so that bootable plunger mechanism moving repeatedly in vertical direction, shown in Fig. 6 and 8, with cylinder hole, front and back B, A is provided with high-pressure oil duct 38 with connecting respectively, 39, low pressure oil duct 40,41, other is provided with a high pressure balance oil pocket 42 and the high pressure compensation oil duct 43 at front end.

As shown in Figure 1, 2, the identical convex wheel body 22 of two shapes of the present invention, they are mutually 90 ° of modes with its peak 34 and are arranged in the oil pump case 12, and are fixed on the pump case circle with four screws 34 respectively and place.Figure 17 and 18 is depicted as the structure of a cam body 22 of the embodiment of the invention, inner chamber has identical cam profile at the two ends of each cam body 22, central authorities between its two ends are provided with circular arc inner chamber 37, match with cantilever arm 33 with the pump housing 14, in this example, every the cam ring molded lines forms by pressing archimedes curve, be respectively equipped with peak 34 and low ebb 44, become two cam rings of arranging symmetrically, as shown in figure 17, cam profile is such formation (with its half 180 ° of analyses of symmetry): the angular distance from following Cheng Gu portion to lift peak portion is 90 °, circles such as summit section is 5 °, and slipping into down Cheng Gu portion section from lift peak portion is 80 °, and circles such as paddy portion section is 5 °, thus, form a periodic duty of plunger for 180 °; 180 ° of layouts of another symmetry are identical, and the pump housing 14 whenever rotates a circle (360 °) like this, rolling at above-mentioned cam profile raceway by roller 9, make twice of every group of plunger to-and-fro motion to finish oil suction and to press oil.

Figure 19 and 20 is depicted as oil distributing member 17 of the present utility model, be tightly connected with the ear end face of oil pump case 12, its sealing is to adopt the sealing scraper ring, its inner chamber fixedly installs an oil distributing shaft outer shroud (mending cover) 16, be provided with two oil inlet holes of dividing equally in the spacing that makes progress in week 45 at described outer shroud 16, with two oil outlets 65, be communicated with oil distributing member turnover oil pocket 46,47 respectively, other is provided with low pressure oil oil inlet and outlet 58,59, filler opening 58 is communicated with oil suction chamber 46, and oil outlet 59 draws oil duct 60 and goes out oil pocket 47 and be communicated with by two.

Fig. 9 to 14 is depicted as oil distributing shaft 18 of the present utility model, be arranged in the outer shroud (lining) 16 in the oil distributing member, its front-end face F is spirally connected by the rear end of four screws 54 with the pump housing 14, on front-end face F, be provided with four low pressure oil oil inlet holes 48, on the cylndrical surface of end face F nearby, be provided with in vertical direction, following each oil distributing hole 49, top two of oil distributing hole 49 and oil inlet hole 48 are communicated with on it, oil distributing hole 49 is communicated with following two oil inlet holes 48 under it, oil inlet hole 48 is aimed at four the low pressure oil oil canals 41 on the pump housing 14 ear end faces and is communicated with, and low pressure oil is directly introduced in the low pressure oil pocket of A oil cylinder; Also be provided with the low pressure oil duct 40 that connects with pump housing B oil cylinder in addition and aim at two low pressure oilholes 51 that are communicated with, on oil distributing shaft and substantially horizontals oil distributing hole 49 same cylndrical surface, be respectively equipped with two oil distributing holes 52, described low pressure oilhole 51 is communicated with respectively with oil distributing hole 52, and the cross-section area of each low pressure oilhole 51 equals the cross-section area sum of described two low pressure oilholes 48, equates to guarantee the oil inlet quantity that enters A, B two cylinder low pressure oil ducts; Be provided with high pressure oilhole 50 in the center of oil distributing shaft 18,, directly draw the high-pressure oil duct oil of (or feeding) A cylinder to be communicated with the A cylinder high-pressure oil duct of the pump housing; As shown in the figure, on front-end face F, also establish two high pressure oilholes 53 in addition, they are aimed at the high-pressure oil duct 38 of the B cylinder high-voltage oil cavity that feeds the pump housing 14 respectively and are communicated with, the cross-section area of these two high pressure oilholes 53 equal described high pressure oilhole 50 cross-section area so that respectively (feeding) to draw the high-pressure channel oil mass of A, B cylinder equal.

As mentioned above, like this, on the cylndrical surface of oil distributing shaft 18, be provided with two groups respectively corresponding to the oil distributing hole 49,52 of A, B cylinder; Because described outer shroud 16(lining) be to be fixed on to reach on the pump housing outside in the oil distributing member 17, and oil distributing shaft 18 is with the pump housing 14 rotations, therefore described oil distributing hole 49,52 just can be respectively alternately with outer shroud 16 circumference of oil distributing shaft 18 on two oil inlet holes 45 and two oil outlets 46 arranged match, to form the turnover hinge of low pressure oil.

Shown in Figure 12,13, on the ear end face of oil distributing shaft 18, be provided with two groups of high pressure oil distributing holes 56,57; Wherein two-supremes is press-fitted oilhole 57 and is communicated with center high pressure oilhole 50 so that divide two-way to draw A cylinder high pressure oil by a transition oil duct 58, wherein in addition two-supremes is press-fitted oilhole 56 and is communicated with described high pressure oilhole 53 by two transition oil ducts 55 respectively, to draw B cylinder high pressure oil respectively.

Figure 15 and 16 is depicted as oil distribution casing 17 of the present utility model, ear end face R driving fit by front-end face M plane and oil distributing shaft 18, thereafter end face cooperates with end cap 20 and is fixedly connected, on oil distribution casing 17, be respectively equipped with oil inlet hole 59, oil outlet 61, oil inlet hole is arranged to long waist shaped, on the cylinder of oil distribution casing, radially be provided with two oil input channels 60 that connect with oil inlet hole 59, two long waist shaped reamings 60 are connected with oil outlet, the center is provided with a small through hole, its front end is aimed at the aperture 63 of the ear end face of oil distributing shaft 18 and is communicated with, so that being introduced transition oil duct 64, the high-pressure and hydraulic compensation oil of the oil outlet of end cap 20 enters small through hole 65, because of small through hole 65 is that the high pressure compensation oil duct of aiming on the pump housing ear end face 43 is guided in the counter balance pocket 42 of pump housing front end, therefore, the hydraulic coupling of high-voltage oil liquid changes and makes the oil distribution casing rubbing surface is subjected to constant less end thrust.

As shown in Figure 1, end cap 20 is tightly connected with the ear end face of oil distributing member 17, oil seal circle is adopted in its sealing, and end face is provided with three high pressure oil through hole 67(that are communicated with oil distribution casing 19 rear end high pressure oilholes 61 and 66 and sees Fig. 1 thereafter, only illustrates one among the figure) they all respectively with 68 perforations of high pressure oil road.

As mentioned above, the two groups of high pressure oil distributing holes 56,57 on the oil distributing shaft 18 be installed in pump housing end cap 20 on two oil inlet holes 59 and 61 driving fits mutually of oil distribution casing 19, to constitute the hinge of high-voltage oil liquid turnover.

As shown in Figure 4, when pump housing 14(as rotor) when rotation, above-mentioned high and low pressure fluid hinge is periodically oil-feed and fuel-displaced respectively, differ from 90 ° because the peak portion position of two cams is alternate, therefore two oil cylinder A, B just alternately press oil, fuel-displaced is evenly and balance.

As shown in Figure 1 and Figure 4, during oil pump work, by a motor (not shown), drive main shaft 4 high speed rotating by key 5, drive the pump housing together with cylinder sleeve 13 high speed rotating by drive plate 24, because the side of described low-pressure plunger 11 is provided with guide pin 30 set on the cantilever arm 33 of guiding groove and the pump housing 14 and matches, therefore by rotating centrifugal inertial force, all the time make roller 9 be close to the interior raceway running of cam 22, and make the roller plunger mechanism reciprocating in the cylinder hole of the pump housing 14, pass through high respectively corresponding to different operating modes, low pressure oil duct and make the work of high low pressure plunger is finished oil suction and is pressed oily process by the volume-variation that corresponding plunger (or high-pressure plunger or low-pressure plunger work) cooperates with cylinder sleeve.

Adopt the more existing plunger-type fuel pump of such scheme of the present invention that following obvious advantage is arranged:

One, little, the compact conformation of volume;

Two, owing to two groups of in turn oil transportations of plunger of employing, so oil transportation is steady;

Three, because this double cam has symmetrical cam slideway, active force can correspondingly offset to reach balance work during work, so radial support power is little, only needs to adopt small size bearing;

Four, adopt roller and cam slideway rolling friction fit system, can reduce relative direct friction face, make fastness obtain long service life.

Five, oil pump join the shunting that oily passage can be realized high and low hydraulic oil, to adapt to different working condition requirements, to reach energy-conservation purpose.

Six, low-pressure hydraulic oil is radially joined oil by the bearing retaining, and oil transportation is simple in structure.

Seven, high hydraulic oil part is joined oil with axial plane, precision height, reliable working performance, and the axial plane thrust-bearing is housed and the high-pressure and hydraulic oil subsidy is repaid the mutual balance of device end thrust at the other end.

Eight, each is all offseted by pump housing cantilever arm the plunger lateral force, thereby has reduced the plunger side wear.

Nine, component are few, simple in structure, and processing and assembly process process are good, thereby the easily manufactured cost that makes reduces greatly.

Claims (5)

1, a kind of high-pressure radial formula plunger-type fuel pump, it comprises: an oil pump case; One bearing support that is spirally connected with described oil pump case front end, in establish forward and backward radial bearing and the plain thrust bearing between them; One working spindle is bearing on described each bearing; Be located at the oil sealing on each matching trim of oil pump; And pump oil operation mechanism, oil distribution mechanism is characterized in that, the oily operation mechanism of described pump comprises: a rotation pump housing, it is arranged in the described oil pump case, and its front end sets firmly a drive plate, and described drive plate is connected with key with rear-end of spindle and is bearing on the radial bearing of described back; Its rear end fix an oil distributing shaft and be bearing in its outer shroud (or on the lining so that the described pump housing can rotate with described main shaft around the housing central axis, in the described pump housing, be provided with two mutual equalitys and perpendicular to the identical cylinder hole of described central axis; Two high-voltage oil cylinders cover is located at the intermediate portion in described respective cylinder hole respectively so that each cylinder hole is divided into upper and lower two cylinders; Two groups of high low pressure combined plunger branches are located in each upper and lower cylinder, and described plunger end is partly installed a roller; Two hyperbola cam bodies are located on the axial central position of each oil cylinder respectively and are mutually 90 ° of ground by its lift peak portion and are fixed on the housing, so that when the pump housing rotates together with oil cylinder, by the rotating inertia force of each plunger make roller rest on cam race upper edge cam profile reciprocating when realizing the work of high low pressure plunger fuel feeding alternately continuously; Described oil distribution mechanism comprises: low pressure oil oil distribution mechanism and high pressure oil oil distribution mechanism, described low pressure oil oil distribution mechanism by the low pressure oil duct in the pump housing and the cylinder sleeve, be arranged on a oil distributing member between pump case and end cap, be arranged on oil distributing shaft in the oil distributing member inner chamber and the outer shroud of oil distributing shaft is formed, described oil distributing member is provided with low pressure oil and imports and exports; Described high pressure oil oil distribution mechanism is arranged between oil distributing shaft and the end cap and with the high pressure oil distribution casing that end cap sets firmly by high-pressure oil duct in the pump housing and the cylinder sleeve and oil distributing shaft to be formed, and described end cap is provided with the high pressure oil oil road.

2, high-pressure radial formula plunger-type fuel pump as claimed in claim 1, it is characterized in that, the molded lines of described hyperbola convex wheel body is to be made up of with the circular arc portion such as grade the symmetrically arranged Archimedes spiral that lift peak portion and following Cheng Gu portion form, 180 ° of scopes of each cam ring molded lines comprise: from paddy portion to peak portion is 90 °, peak portion scope is 5 ° and waits circular arc, slipping into paddy portion from peak portion is 80 °, and paddy portion scope is 5 ° and waits circular arc, so that form a to-and-fro motion of plunger.

3, high-pressure radial plunger oil pump as claimed in claim 1, it is characterized in that, comprise also-compensation hydraulic mechanism that it comprises internal oil channel and the balance oil pocket between pump housing front end and rear-end of spindle portion that is arranged on compensation oilhole, oil distributing shaft and the pump housing in the described oil distribution casing and is arranged on oil pocket interior a balance spring and spring seat; Bear so that the oil distribution casing Transverse plane is subjected to constant less end thrust the axial force of high-pressure and hydraulic compensation oil and spring support force with joint efforts by the plane bearing of main shaft.

4, high-pressure radial formula plunger-type fuel pump as claimed in claim 1, it is characterized in that, the described pump housing is corresponding to upper and lower and left and right four cantilever arms that are provided with symmetrically of the periphery of each central position, cylinder hole, so that pump housing when rotation, the lateral force of all bearing plunger in 360 ° of scopes is to improve the force-bearing situation of roller engagement rolling.

5, high-pressure radial formula plunger-type fuel pump as claimed in claim 4, it is characterized in that, two centrosymmetric cantilever arms of the described pump housing are provided with guider screw, and described low-pressure plunger side direction is provided with guiding groove with matching, in order to avoid the reciprocating sideshake of plunger.

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