CN114060265A

CN114060265A - Plunger matching part, plunger sleeve and high-pressure pump

Info

Publication number: CN114060265A
Application number: CN202010791341.0A
Authority: CN
Inventors: 潘一帆; 伍中宇; 张满意
Original assignee: United Automotive Electronic Systems Co Ltd
Current assignee: United Automotive Electronic Systems Co Ltd
Priority date: 2020-08-07
Filing date: 2020-08-07
Publication date: 2022-02-18

Abstract

The invention relates to a plunger and barrel assembly, a plunger sleeve and a high-pressure pump, which can better solve the problem that the larger the plunger gap leakage is along with the rise of the pressure of pump oil, improve the oil supply efficiency, ensure the service life of the plunger and barrel assembly and reduce the use cost.

Description

Plunger matching part, plunger sleeve and high-pressure pump

Technical Field

The present invention relates to a high pressure pump for performing secondary compression of a primary pressurized fluid introduced therein, and more particularly, to a plunger type high pressure pump, and more particularly, to a plunger and barrel assembly and a plunger sleeve in a high pressure pump.

Background

The high-pressure pump is a key part of a direct fuel injection engine and is generally configured as shown in fig. 1. A plunger and barrel assembly is arranged in a pump body 1 of the high-pressure pump and comprises a plunger 2 and a plunger sleeve 3, and the plunger 2 is movably inserted into the plunger sleeve 3. In actual use, the plunger 2 makes reciprocating linear motion under the pushing of external force, so that the volume and the pressure in the working chamber 4 are changed, the downward movement of the plunger 2 forms negative pressure in the working chamber 4, fuel enters the working chamber 4 through the suction valve 5, liquid in the working chamber 4 is squeezed along with the upward movement of the plunger 2, the pressure is increased, and finally the discharge valve 6 is opened to discharge the fuel in the working chamber 4, so that the aim of conveying high-pressure fuel (the pressure is 150bar or more) is fulfilled. Under the condition, the fuel oil is pressed into the fuel supply pipeline from the fuel tank by the fuel delivery pump at the front end, and the pressure of the fuel oil is increased after the fuel oil is subjected to secondary compression by the high-pressure pump, so that the aim of improving the fuel combustibility of the vehicle engine is fulfilled.

At present, with the continuous improvement of national requirements on energy conservation and emission reduction, the pressure of a high-pressure direct injection system is also continuously improved, for example, the pressure of pump oil is increased to 350bar or more on the premise of not losing light weight. For this reason, the design and manufacture of high-pressure pumps face new challenges. Specifically, as the pump oil pressure increases, the more easily the high-pressure oil flows back to the low-pressure region 7 in the pump body 1 through the plunger gap g (i.e., the seal gap between the plunger 2 and the plunger sleeve 3), which causes an increase in the problem of a decrease in volumetric efficiency of the engine. Therefore, the higher the pump oil pressure, the larger the gap leakage. The problem is particularly obvious when the engine is in a working condition of medium and low rotating speed, so that the oil supply capacity of the medium and low rotating speed becomes the bottleneck capacity of a higher-pressure oil pump. If the prior art route is used, crevice leakage at medium and low rotational speeds at next generation system pressures (500bar and above) becomes the dominant source of fuel supply efficiency loss, the amount of fuel supply can become even so small that further increases in system pressure for direct injection systems become impossible. For this reason, it is necessary to solve the problem that the gap leakage becomes larger as the pump oil pressure increases, thereby improving the oil supply efficiency.

Disclosure of Invention

In order to solve the above technical problems, an object of the present invention is to provide a plunger and barrel assembly, a plunger sleeve and a high pressure pump, which aims to reduce the actual plunger clearance, improve the oil supply efficiency, and when improving the oil supply efficiency, the weight of the whole high pressure pump is not increased, and the service life of the parts is ensured, and at the same time, the plunger wear is reduced, and the problem of plunger jamming during the movement is ensured.

In order to achieve the above object, according to a first aspect of the present invention, there is provided a plunger and barrel assembly comprising a plunger, a plunger sleeve and rolling bodies; the plunger sleeve is provided with an inner hole which is axially communicated, and the plunger is movably arranged in the inner hole in a penetrating way; an annular groove is formed in the inner circumferential surface of the inner hole between the two ends, and a plurality of rolling bodies are filled in the annular groove; each rolling element is dimensioned to be able to be prevented from entering a plunger gap, and is further configured to be able to move in the annular groove.

Optionally, the number of the annular grooves is one or more, and a plurality of the annular grooves are arranged at intervals along the axial direction of the plunger sleeve.

Optionally, the annular groove is sized to accommodate a plurality of the rolling elements in an axial direction of the bore, and is further sized to accommodate one or more of the rolling elements in a radial direction of the bore.

Optionally, in the axial direction of the inner bore, a plurality of the rolling elements fill the entire annular groove, or a plurality of the rolling elements fill a part of the height of the annular groove.

Optionally, the rolling bodies have the same or different structure, including the shape and/or size of the rolling bodies.

Optionally, the rolling elements are regularly shaped or irregularly shaped.

Optionally, the rolling elements are spherical and have a diameter of 1.0 μm to 100 μm.

Optionally, the material of the rolling body is a metal material or an inorganic non-metal material.

Optionally, a groove gap is provided between the annular groove and the plunger; in the radial direction of the inner hole, the difference between the groove gap and the width filled by the rolling body is 0.5-5.0 μm.

Optionally, the plunger gap is greater than or equal to 0.5 μm and less than 70 μm.

In order to achieve the above object, according to a second aspect of the present invention, there is provided a plunger barrel for a plunger and barrel assembly as described above.

In order to achieve the above object, according to a third aspect of the present invention, there is provided a high-pressure pump comprising a pump body and the plunger and barrel assembly, wherein the plunger and barrel assembly is disposed in the pump body.

The plunger and barrel assembly, the plunger sleeve and the high-pressure pump provided by the invention have the following advantages:

firstly, in a plunger and barrel assembly of a high-pressure pump, a rolling body is filled between a plunger and a plunger barrel, so that a gap between the plunger and the plunger barrel (namely a plunger gap) can be reduced or even small through free filling of the rolling body, and the higher the pressure of pump oil is, the larger the stacking effect of the rolling body is, the smaller the leakage gap is, therefore, the leakage gap can be self-adaptive to the change of pressure, and the negative effect that the leakage rate is increased along with the increase of the pressure is just compensated; therefore, the problem that the larger the gap leakage is caused by the rise of the pressure of the pump oil can be better solved, the oil supply efficiency is greatly improved, and the arrangement mode can not increase the weight and the manufacturing cost of the high-pressure pump;

secondly, the motion of the plunger can be lubricated in an auxiliary way through the rolling of the rolling body, so that the sliding friction between the plunger and the plunger sleeve is converted into rolling friction, the abrasion between the plunger and the plunger sleeve is reduced, the service life of a plunger matching part is ensured, and the cost is further reduced; the rolling body can freely move in the annular groove when the plunger moves, so that hard contact with the plunger does not exist, and the problem of contact friction aggravation caused by part deformation or plunger clamping caused by overheating due to local instantaneous dry friction is further prevented; in addition, the arrangement of the rolling body enables the actual plunger gap to be processed to be smaller, at the moment, the plunger clamping problem cannot be caused even if the plunger gap is reduced, the rolling body with a smaller size is favorably selected for filling, the leakage is further reduced, the oil supply efficiency is improved, or the arrangement of the rolling body enables the actual plunger gap to be processed to be larger, the processing precision of the plunger gap is reduced, and the processing cost is reduced;

and thirdly, the annular grooves are preferably multiple and are arranged at intervals in the axial direction of the plunger sleeve, so that a plurality of layers of gap sealing belts can be formed in the axial direction, the sealing effect is better, the leakage is further reduced, and the oil supply efficiency is improved.

Drawings

It will be appreciated by those skilled in the art that the drawings are provided for a better understanding of the invention and do not constitute any limitation to the scope of the invention. In the drawings:

FIG. 1 is a schematic view of the internal structure of a prior art high pressure pump;

FIG. 2 is a schematic diagram of the internal structure of a high pressure pump in a preferred embodiment of the present invention, wherein the high pressure pump is in the suction stroke;

FIG. 3 is a schematic view showing the internal structure of the high-pressure pump in the preferred embodiment of the present invention, wherein the high-pressure pump is in the oil supply pressurizing stroke;

FIG. 4 is a schematic diagram of a calculation of a gap occupancy in an embodiment of the present invention;

FIGS. 5 and 6 are schematic views illustrating assembly of rolling elements according to exemplary embodiments of the present invention, respectively;

FIG. 7 is a graph of cam speed versus fuel delivery efficiency in a non-combustible test oil at 350bar in an embodiment of the present invention.

Description of reference numerals:

a pump body 1; a plunger 2; a plunger sleeve 3; a working chamber 4; a suction valve 5; a discharge valve 6; plunger gap g; a low-pressure region 7;

a high-pressure pump 10; a pump body 11; a plunger 12; a plunger sleeve 13; rolling bodies 14; plunger gap g'; an annular groove 131; a high pressure chamber 15.

The same or similar reference numbers in the drawings identify the same or similar elements.

Detailed Description

The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention. It should be noted that the drawings provided in the present embodiment are only for illustrating the basic idea of the present invention, and the components related to the present invention are only shown in the drawings rather than drawn according to the number, shape and size of the components in actual implementation, and the type, quantity and proportion of the components in actual implementation may be changed freely, and the layout of the components may be more complicated.

Furthermore, each of the embodiments described below has one or more technical features, and thus, the use of the technical features of any one embodiment does not necessarily mean that all of the technical features of any one embodiment are implemented at the same time or that only some or all of the technical features of different embodiments are implemented separately. In other words, those skilled in the art can selectively implement some or all of the features of any embodiment or combinations of some or all of the features of multiple embodiments according to the disclosure of the present invention and according to design specifications or implementation requirements, thereby increasing the flexibility in implementing the invention.

To further clarify the objects, advantages and features of the present invention, a more particular description of the invention will be rendered by reference to the appended drawings. It is to be noted that the drawings are in a very simplified form and are not to precise scale, which is merely for the purpose of facilitating and distinctly claiming the embodiments of the present invention. As used in this specification, the singular forms "a," "an," and "the" include plural referents unless the content clearly dictates otherwise. As used in this specification, the meaning of "a plurality" generally includes two or more unless the content clearly dictates otherwise. As used in this specification, the term "or" is generally employed in its sense including "and/or" unless the content clearly dictates otherwise. The term "axial" generally refers to a direction parallel to the axis of the part, "radial" generally refers to a direction perpendicular to the axial direction and directed toward the axis, and "circumferential" generally refers to a direction about the axis of the part. It is also to be understood that the present invention repeats reference numerals and/or letters in the various embodiments. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed. It will also be understood that when an element is referred to as being "connected" to another element, it can be directly connected to the other element or one or more intervening elements may be present.

As in the background art, as the pressure of the pumping oil increases, the more easily the high-pressure oil flows back to the low-pressure region in the pump body through the plunger clearance, and the problem of the decrease of the volumetric efficiency of the engine is further serious. To address this technical problem, the solutions proposed in the industry are as follows:

scheme 1, a larger oil pumping volume is selected to make up for loss caused by volume efficiency reduction;

scheme 2, the length of a plunger clearance section is increased, and the clearance backflow loss is reduced;

scheme 3, the machining gap of the plunger pair is reduced, and the loss of gap backflow is reduced;

scheme 4, an O-shaped ring is used for sealing between the plunger and the plunger sleeve.

The inventors have found that the above solutions all have some problems:

in the scheme 1, the lift or the diameter of the plunger needs to be increased, so that the plunger leakage is increased, the improvement on the oil supply efficiency is limited, the cost is increased along with the increase of the weight, and meanwhile, a larger driving force needs to be provided, and the power consumption is increased;

in the

schemes

2 and 3, along with the risk that the service life is obviously reduced due to the accelerated abrasion of the plunger pair, the existing processing technology of the plunger clearance approaches to the limit of normal operation of the plunger, and the problem that the plunger is blocked easily due to further compression of the clearance or increase of the clearance length is solved; the sliding friction between the existing plunger and the plunger sleeve causes severe abrasion, and the plunger is more seriously abraded and is more easily blocked under the condition of small plunger clearance;

in the scheme 4, the requirement on the wear resistance of the O-shaped ring is very high, the service life of the known O-shaped ring is difficult to meet the requirement under the severe working conditions of high speed and high temperature of high-pressure oil, and the final use cost is very high.

It follows that the problem of the larger gap leakage with the increase in the pump oil pressure is not solved well, and even if the related solution is proposed, the oil supply improvement efficiency is very limited, and the cost is high, so that the abrasion of the plunger is aggravated and the plunger movement is locked.

Based on the research, the invention provides a novel plunger and barrel assembly, aiming at reducing the leakage clearance of a plunger through the filling of a rolling body in an annular groove of a plunger sleeve, thereby improving the oil supply efficiency, and even if the pressure of pump oil is increased, the volume efficiency can not be reduced, so that the subsequent higher-pressure pump oil is easy to realize.

In order to achieve the purpose, the plunger and barrel assembly provided by the invention specifically comprises a plunger, a plunger sleeve and a rolling body, wherein the plunger sleeve is provided with an inner hole which is axially communicated, and the plunger is movably arranged in the inner hole in a penetrating manner; the inner hole is provided with an annular groove on the inner circumferential surface between two ends, the annular groove is filled with a plurality of rolling bodies, each rolling body is configured to be prevented from entering a plunger gap, and each rolling body is also configured to be capable of moving in the annular groove. Here, the plunger clearance refers to a clearance between the plunger and an inner circumferential surface of the inner bore of the plunger barrel, in which the annular groove is not formed. It can be understood that the leakage gap between the plunger and the plunger sleeve can be reduced by freely filling the rolling body, thereby greatly reducing the gap leakage and effectively improving the oil supply efficiency. In particular, the higher the pumping pressure, the greater the accumulation effect of the rolling elements and the smaller the leakage gap, so that the leakage gap can adapt to the pressure change, and the defect that the leakage rate becomes larger along with the pressure rise is overcome. Therefore, the problem that the larger the gap leakage is caused by the increase of the pressure of the pump oil can be better solved, the oil supply efficiency is greatly improved, and the weight and the manufacturing cost of the high-pressure pump are not increased.

Not only here, the plunger motion can also be through the roll of rolling element can the auxiliary lubrication, makes the sliding friction between plunger and the plunger bushing change into rolling friction, has reduced the wearing and tearing between plunger and the plunger bushing, has guaranteed the life of plunger matching parts, has reduced use cost. Meanwhile, the rolling body can freely move in the annular groove when the plunger moves, hard contact with the plunger does not exist, and the problem of contact friction aggravation caused by part deformation or plunger blocking caused by overheating due to local instantaneous dry friction is further prevented. In addition, the setting of rolling element for the actual plunger clearance can be processed littleer, at this moment, even the plunger clearance is little, also can guarantee that the plunger motion is normal, the dead problem of plunger motion card can not appear, and can further reduce the leakage, promote fuel feeding efficiency, perhaps, the setting of rolling element makes the actual plunger clearance can be processed bigger, thereby reduces the processing cost of plunger.

In particular, the plunger and barrel assembly of the present invention may be used with a plunger gap of greater than or equal to 0.5 μm and less than 70 μm. More specifically, for gasoline engines and diesel engines, the plunger clearance of these engines is generally 1 μm to 20 μm, for example, the plunger clearance of gasoline engines is mainly 10 μm, and the plunger clearance of diesel engines is mainly 2 μm to 3 μm. After the plunger and barrel assembly is applied, the plunger clearance of the engine can be allowed to be processed to be larger, and under the condition, the oil supply efficiency is ensured, meanwhile, the processing precision of the plunger clearance can be reduced, and the manufacturing cost is reduced. In addition, the plunger clearance of the engine can be allowed to be processed to be smaller, at the moment, the problem of plunger jamming can still be avoided, the oil supply efficiency can also be ensured, and the small-size rolling body can be favorably used in the plunger matching part with the small plunger clearance, so that the leakage area is reduced. Alternatively, the plunger clearance of the plunger and barrel assembly of the present invention may be the same as the existing plunger clearance. It should be understood that the size of the plunger gap of the present invention is mainly set according to the size of the rolling elements as long as the plunger gap can prevent the rolling elements from falling into the plunger gap, and thus, the plunger gap is designed to be smaller than the size of the rolling elements.

In more detail, the gathering form of the rolling bodies in the annular groove has the self-adaptive characteristic, and due to the self-adaptive characteristic, the oil supply leakage is greatly reduced, and the technical bottleneck that the gap leakage is larger along with the increase of the oil pumping pressure is overcome. In particular, a first advantage of the adaptive clustering of the rolling elements in the annular groove is: when the high-pressure pump is in the oil supply pressurization stroke, along with the rising of pressure in the high-pressure cavity in the pump body, the rolling body can be intensively pressed to the bottom of the annular groove and stacked together to form a sealing area with higher density than that in a normal state, so that the plunger clearance is further compressed, and the oil supply efficiency can achieve the best promotion effect. Therefore, the higher the pumping oil pressure is, the greater the accumulation benefit of the rolling body is, and the smaller the gap leakage is, so that the gap leakage can be adaptive to the change of the pumping oil pressure, and the defect that the leakage rate is increased along with the increase of the pressure is overcome. A second advantage of the adaptive accumulation of the rolling bodies in the annular groove is: when the high-pressure pump is in the oil suction stroke, the high-pressure cavity in the pump body returns to the normal pressure, the rolling bodies can be randomly distributed in the annular groove, the free motion contact points between the rolling bodies and the plunger and between the rolling bodies and the plunger sleeve can be randomly changed due to the rolling of the rolling bodies, and the contact stress cannot be always concentrated on the fixed parts of the plunger and the plunger sleeve, so that unnecessary abrasion among the rolling bodies, the plunger and the plunger sleeve is prevented, the service life of a plunger matching part is ensured, and the use cost is reduced. A third advantage of the adaptive accumulation of the rolling bodies in the annular groove is: the rolling element need not be covered with whole annular groove, and pump oil pressure can be automatic with rolling element compression gathering in one department formation clearance sealing strip, whenever can both form good sealed, and sealed flexibility is strong, and the rolling element has abundant space in addition when also can help the oil absorption stroke can free movement, avoids forming hard contact with the plunger, avoids the stress concentration at a position, reduces the wearing and tearing of rolling element, plunger bushing and plunger.

It should be noted that the shape of the annular groove is not particularly limited in the present invention, and includes both the axial sectional shape and the cross-sectional shape of the annular groove. In addition, in the present invention, the number of the annular grooves may be one, or may be plural (plural includes two, three, or more). When the annular grooves are multiple, the annular grooves are arranged at intervals along the axial direction of the plunger sleeve, so that a plurality of layers of gap sealing belts are conveniently formed in the axial direction, and the leakage is further reduced. For example, the space may allow for three or more annular grooves to be formed in the plunger sleeve, which may be equally or unequally spaced.

In the invention, the structure of the annular groove can be a continuous ring of groove or a plurality of sub-grooves which are symmetrically distributed around the axis of the inner hole. Preferably, the annular groove is a continuous and uninterrupted ring of grooves, the processing is convenient, a gap sealing belt is formed in a circumferential ring, and the leakage rate is smaller. In addition, when the annular grooves are multiple, all the annular grooves can be designed into a continuous ring of grooves, all the annular grooves can also be designed into a groove structure formed by multiple sub-grooves, and some of the annular grooves can also be designed into a continuous ring of grooves, and other annular grooves can be designed into a groove structure formed by multiple sub-grooves. Further, when the annular groove is a plurality of annular grooves, if at least a part of the annular grooves are formed by a plurality of sub-grooves, it is further preferable that the sub-grooves of different annular grooves are staggered in the circumferential direction in the annular groove formed by the sub-grooves, that is, the sub-grooves of different annular grooves are on the same projection plane perpendicular to the axial direction, and the sub-grooves of different annular grooves are not overlapped, for example, one annular groove is formed by four first sub-grooves, and the other annular groove is formed by four second sub-grooves, and at this time, one or more second sub-grooves can be arranged between any two adjacent first sub-grooves in the circumferential direction on the same projection plane perpendicular to the axial direction, so that a circle of gap can be formed in the circumferential direction, and leakage can be reduced.

The number of the rolling bodies arranged in the annular groove is not limited, the distribution mode of the rolling bodies in the annular groove is not limited, the rolling bodies can be freely and randomly distributed in the annular groove, and the rolling bodies can be densely distributed in the circumferential direction and the radial direction of the annular groove. Here, the expression "dense distribution is formed in the circumferential direction" means that the rolling elements are adjacent to each other in the circumferential direction of the annular groove, and may or may not overlap each other; similarly, the phrase "dense distribution in the radial direction" means that the rolling elements are adjacent to each other in the radial direction of the annular groove, and may or may not overlap each other.

Furthermore, in order to form a dense distribution, the annular groove is dimensioned to accommodate a plurality of rolling elements in the axial direction of the bore, i.e. a plurality of rows of rolling elements (which may be two or three or more rows) are formed in the axial direction of the annular groove, and the annular groove is also dimensioned to accommodate one or more rolling elements in the radial direction of the bore, which may be two, three or more. It will be understood that when the annular groove is a continuous, uninterrupted ring of grooves, the ring of grooves is sized to accommodate a plurality of said rolling elements in the axial direction of the bore, and the ring of grooves is also sized to accommodate one or more of said rolling elements in the radial direction of the bore. Furthermore, the circular groove is preferably a circular ring-shaped groove, so that the processing is simple, burrs are not generated, the abrasion is not easy to occur, and the strength is high. It will also be appreciated that when the annular recess is formed by a plurality of sub-recesses, each sub-recess is dimensioned to receive a plurality of said rolling elements in the axial direction of said bore, and each sub-recess is also dimensioned to receive one or more of said rolling elements in the radial direction of said bore. And the size of the ring of grooves or each sub-groove is also required to ensure that the rolling bodies can move freely in the grooves to form rolling friction.

Furthermore, in the axial direction of the plunger and barrel assembly, the plurality of rolling bodies may fill the entire annular groove, that is, the entire height of the annular groove in the axial direction is filled with the rolling bodies. Alternatively, in the axial direction of the plunger and barrel assembly, the part of the height of the annular groove in the axial direction is filled with the rolling bodies. In general, the minimum height at which the rolling bodies fill the annular groove in the axial direction is set according to the degree of reduction of the gap area.

Further, the shape of the rolling elements in the or each ring of grooves may be the same or different. Furthermore, the rolling elements in the ring of grooves or each sub-groove may be the same or different in size, preferably different in size, so as to facilitate a more compact distribution. The shape of the rolling body is not limited, and the rolling body can be regular or irregular, such as polyhedron, ellipsoid, sphere and the like, and the regular shape is more preferable, so that the rolling body is conveniently distributed more compactly, and is not easy to wear. Preferably, the rolling elements have a spherical shape. The material of the rolling body is not limited, and is mainly selected from materials with high wear resistance and high strength, preferably, the material of the rolling body is a metal material or an inorganic non-metal material, and for example, the material can be selected from stainless steel, quartz (such as glass powder or spherical silicon powder), ceramics (such as tungsten carbide) or gravel and the like. For example, the balls made of stainless steel can be selected to serve as rolling bodies, or sand grains are selected to serve as the rolling bodies, the hardness of the sand grains can reach 8-9 Mohs hardness, the higher hardness can guarantee the higher wear resistance, the shape of the sand grains is preferably a regular shape, and the filling compactness is guaranteed. The size of the rolling element is set according to the size of the plunger gap, for example, the existing plunger gap is 1 μm to 20 μm, and when the rolling element is spherical, the diameter of the rolling element is slightly larger than the plunger gap, for example, the diameter of the rolling element is larger than 1 μm and smaller than or equal to 100 μm, further optionally, the diameter of the rolling element is 5 μm to 70 μm, and preferably, the diameter of the rolling element is 10 μm.

Furthermore, the invention also protects a plunger sleeve for the plunger matching part, and the annular groove is formed between the two ends of the inner hole of the plunger sleeve, so that the rolling body is conveniently filled in the annular groove, and the effect is achieved. Furthermore, the invention also protects a high-pressure pump, which comprises a pump body and the plunger and barrel assembly, wherein the plunger and barrel assembly is arranged in the pump body. The high-pressure pump provided by the invention has the advantages of high oil supply efficiency, low cost and high reliability of plunger movement. Furthermore, the invention also protects a fuel direct injection engine, which adopts the high-pressure pump of the invention, thus the fuel supply efficiency is high, the power is obviously improved, and the fuel consumption is effectively reduced.

The present invention will now be described in further detail with reference to the drawings and preferred embodiments to more fully appreciate the features and characteristics of the embodiments described herein.

Fig. 2 is a schematic view of the internal structure of the high-pressure pump in the preferred embodiment of the present invention. As shown in fig. 2, the present embodiment relates to a high-pressure pump 10, which is mainly used in a vehicle-mounted fuel direct injection engine, such as a gasoline engine or a diesel engine, or other similar application scenarios, such as ship, chemical engineering, oil exploitation, oil field pipelines, metallurgy, agricultural machinery, and the like.

The high-pressure pump 10 specifically includes a pump body 11 and a plunger and barrel assembly. The plunger and barrel assembly comprises a plunger 12 and a plunger sleeve 13. The plunger 12 is movably disposed in the pump body 11, and receives power transmitted from the outside of the pump body 11 to perform a reciprocating linear motion. The plunger sleeve 13 has an inner hole (not labeled) running through in the axial direction, and the plunger 12 is movably arranged in the inner hole of the plunger sleeve 13 in a penetrating way so as to do reciprocating linear motion relative to the plunger sleeve 13.

Different from the structure of the existing plunger sleeve, the inner hole of the plunger sleeve 13 of the embodiment has non-uniform aperture, small aperture at both ends, and large aperture in at least a part of the middle area. Specifically, at least one annular groove 131 is formed on the inner circumferential surface of the inner bore of the plunger sleeve 13 between the two ends, the annular groove 131 is a continuous and uninterrupted ring groove, and a plurality of rolling bodies 14 are filled in the annular groove 131. Each rolling element 14 is dimensioned to prevent it from entering the plunger gap g ', so that the rolling elements 14 do not fall into the plunger gap g' during use of the high-pressure pump 10. Here, the plunger gap g' is defined as described above, meaning that there is no gap between the inner circumferential surface of the annular recess 131 formed in the inner bore of the plunger sleeve 13 and the plunger 12. In actual use, the size of the rolling elements 14 cannot be made too large, and if the size of the rolling elements 14 is made too large, the gap between the rolling elements 14 is also made large, which is disadvantageous in forming a dense distribution. In this embodiment, the rolling element 14 is preferably spherical, and the diameter thereof is slightly larger than the plunger gap g', for example, the diameter d of the rolling element 14 is: 1 μm < d.ltoreq.100. mu.m, preferably 5 to 70 μm, more preferably 10 μm. As described above, the plunger gap g 'is different between the diesel engine and the gasoline engine, and the size of the rolling elements 14 is set according to the size of the plunger gap g' in the diesel engine and the gasoline engine in actual use.

Here, after the high-pressure pump 10 is applied, the clearance between the plunger 12 and the plunger sleeve 13 is made small by the free filling of the rolling elements 14, and the leakage clearance is made smaller as the accumulation effect of the rolling elements 14 is larger as the pumping oil pressure is higher, so that the leakage clearance can be adapted to the change of the pressure, and the clearance leakage does not increase even if the pumping oil pressure is increased, but is smaller, the oil supply efficiency is effectively improved, and the problem that the clearance leakage is larger as the pumping oil pressure is increased can be well solved. And the motion of the plunger 12 can be lubricated in an auxiliary way through the rolling of the rolling body 14, so that the sliding friction between the plunger 12 and the plunger sleeve 13 is converted into rolling friction, the abrasion between the plunger 12 and the plunger sleeve 13 is reduced, the service life of a plunger matching part is ensured, and the cost is further reduced. And, the rolling body 14 can move freely in the annular groove 131 when the plunger 12 moves, there is no hard contact with the plunger 12, further preventing the contact friction aggravation problem caused by the deformation of parts or the plunger 12 seizing problem caused by overheating due to local instantaneous dry friction. In particular, the provision of the rolling body 14 allows the actual plunger gap to be processed smaller, thereby further reducing leakage and improving oil supply efficiency, or the provision of the rolling body 14 allows the actual plunger gap to be processed larger, thereby reducing processing costs. In this embodiment, the plunger gap g ' may be made smaller, for example, the plunger gap g ' of a gasoline engine may be 0.5 μm, 1 μm, 5 μm, and the plunger gap g ' of a diesel engine may be 0.5 μm, 1 μm. Alternatively, the plunger gap g' may be made larger, for example 15 μm, 20 μm, 30 μm for a gasoline engine and 5 μm, 10 μm for a diesel engine. In other embodiments, the plunger gap g' may also be the same as existing plunger gaps, for example 10 μm for gasoline engines and 2 μm or 3 μm for diesel engines.

Specifically, when the high-pressure pump 10 is in the oil supply pressurization stroke, as the pressure in the high-pressure chamber 15 increases, the rolling elements 14 are intensively pressed to a position close to the lower side of the plunger 12 (i.e., the bottom of the annular groove 131, see fig. 3), and are stacked together to form a sealing area with a higher density than that in the normal state, so that the plunger gap g' is further compressed, and the oil supply efficiency can achieve the best improvement effect. In addition, when the high-pressure pump 10 is in the oil suction stroke, the high-pressure chamber 15 returns to the normal pressure, the rolling bodies 14 can be distributed in the annular groove 131 relatively randomly (see fig. 2), and due to the free movement of the rolling bodies 14, the contact points between the rolling bodies 14 and the plunger 12 and the plunger sleeve 13 are changed randomly, the contact stress cannot be concentrated on certain fixed parts all the time, so that unnecessary abrasion of the rolling bodies 14, the plunger 12 and the plunger sleeve 13 is prevented, and the service life of parts is further ensured. Moreover, the rolling elements 14 do not need to fill the whole annular groove 131, pressure can automatically compress and gather the rolling elements 14 at one position to form a gap sealing belt, good sealing can be formed at any time, the sealing flexibility is strong, the rolling elements 14 in an oil suction stroke can be helped to have sufficient space and can move freely, stress concentration of one part is avoided, and abrasion of the rolling elements, the plunger sleeve and the plunger is reduced.

In this embodiment, the number of the annular grooves 131 may be one or more, and the number of the annular grooves may be two, three or more. When the number of the annular grooves 131 is plural, the plural annular grooves 131 are arranged at intervals, for example, at equal intervals or at unequal intervals, along the axial direction of the plunger sleeve 13, so that a multi-layer gap sealing tape is formed in the axial direction, and the leakage-proof effect is better. The sectional shape (e.g., a cross section or an axial section) of the annular groove 131 is not particularly limited and may be a regular shape or an irregular shape, and preferably, the axial sectional shape of the annular groove 131 is a regular shape, such as a rectangle, an ellipse, or a polygon, and more preferably, a rectangle. In this embodiment, the annular groove 131 is preferably cylindrical, and has the advantages of simple processing, no burr, low possibility of abrasion, and high strength.

In an alternative embodiment, the annular groove 131 may also be formed by a plurality of sub-grooves symmetrically arranged around the axis of the inner bore, that is, a plurality of sub-grooves are arranged at intervals on the same circumference, and each sub-groove is filled with the rolling elements 14, so that a gap sealing band may be formed in the circumferential direction to reduce gap leakage.

In some embodiments, when there are a plurality of annular grooves 131, all the annular grooves 131 may be a continuous ring of grooves, or all the annular grooves 131 may be formed by a plurality of sub-grooves. In other embodiments, when the annular groove 131 is plural, some of the annular grooves 131 may be a continuous ring groove, and other annular grooves 131 may be formed by plural sub-grooves. Further, when at least a part of the annular groove 131 is formed by a plurality of the sub-grooves, and among the annular grooves formed by the sub-grooves, the sub-grooves of different annular grooves are preferably arranged staggered in the circumferential direction, which is equivalent to forming a continuous and uninterrupted ring of grooves in the circumferential direction.

In the following description, for convenience of description, the annular groove 131 is a continuous and uninterrupted ring of grooves as an illustration, but should not be taken as a limitation of the present invention.

The annular groove 131 is dimensioned to allow accommodation of one or more side-by-side rolling bodies 14 in the radial direction of the plunger sleeve 13 and/or the annular groove 131 is dimensioned to allow accommodation of a plurality of side-by-side rolling bodies 14 in the axial direction of the plunger sleeve 13. For example, the annular groove 131 can accommodate 1 to 1000 rolling elements 14 in the radial direction of the plunger sleeve 13. Further, in some embodiments, the entire height of the annular groove 131 can be filled with the rolling elements 14 in the axial direction of the plunger coupling, i.e. in the axial direction of the inner bore of the plunger sleeve 13, and at this time, the rolling elements 14 can move freely by using the radial clearance. In an alternative embodiment, only a part of the height of the annular groove 131 is filled by the rolling bodies 14 in the axial direction of the plunger partner, i.e. in the axial direction of the inner bore of the plunger sleeve 13. It will be appreciated that the dimension of the annular groove 131 in the axial direction of the bore is the height of the annular groove, the dimension of the annular groove 131 in the circumferential direction of the bore is the width of the annular groove, and the dimension of the annular groove 131 in the radial direction of the bore is the depth of the annular groove. Further, the rolling elements 14 are preferably spherical.

Next, the case where the gap is reduced after the rolling elements 14 are filled will be further described by specific examples.

FIG. 4 is a schematic diagram illustrating the calculation of the gap occupancy in the embodiment of the present invention. As shown in fig. 4, it is assumed that the annular groove 131 is a continuous and uninterrupted ring groove, and the annular groove 131 is circular, and it is assumed that one rolling element 14 is filled in the radial direction of the annular groove 131, and the rolling element 14 is spherical. In specific calculation, the diameter of the plunger 12 is defined as D, the diameter of the rolling element 14 is defined as D, the plunger gap is defined as G', and the single-sided groove gap between the annular groove 131 and the plunger 12 is defined as G.

In one example, assuming that G is 10 μm, G is 13 μm, and D is 12 μm, considering that the diameter D of the plunger 12 (e.g. the diameter of the plunger of a gasoline engine is generally 9mm, and the diameter of the plunger of a diesel engine is generally 6mm) is much larger than the plunger gap 10 μm, the leak gap size can be expressed by replacing the single-sided gap width of the circumference with the gap area occupancy in the partial rectangle. At this time, the calculation method of the occupation rate of the slit area in the local rectangle is as follows: ball gap cross-section A1/plunger machined gap cross-section A2, where A1 ≈ G × d- (π × d)²/4), A2 ≈ g × d. Thus, A1/A2 ≈ G.times.d-. pi.times.d²And/4)/(gxd) 35.8%. It can be seen that after the rolling element 14 is filled, the gap area after the modification is 35.8% of the original gap area.

In one example, assuming that G ≈ 10 μm, G ═ 18 μm, and d ≈ 16 μm, a1/a2 ≈ G × d-pi × d²And/4)/(gxd) ═ 54.3%. That is, after the rolling elements 14 were filled, the gap area after the modification was 54.3% of the original gap area. It can be seen that, with a constant plunger gap of 10 μm, the greater the radial depth of the annular recess 131, the greater the diameter of the rolling elements 14 and the greater the gap leakage.

In one example, assuming that G ═ 5 μm, G ═ 8 μm, and d ≈ 7 μm, a1/a2 ≈ G × d-pi × d²And/4)/(gxd) 50%. It can be seen that after the rolling element 14 is filled, the gap area after the modification is 50% of the original gap area.

In one example, assuming that G ≈ 5 μm, G ═ 12 μm, and d ≈ 10 μm, a1/a2 ≈ G × d-pi × d²And/4)/(gxd) ═ 82.9%. That is, after the rolling elements 14 were filled, the gap area after the modification was 82.9% of the original gap area. It can be seen that, with a constant plunger gap of 5 μm, the greater the radial depth of the annular recess 131, the greater the diameter of the rolling elements 14 and the greater the gap leakage.

In one example, assuming that G-20 μm, G-73 μm, and d-70 μm, a1/a2 ≈ G × d-pi × d²And/4)/(gxd) ═ 90.1%. It can be seen that, in the case of increasing the plunger gap to 20 μm, if the radial depth of the annular groove 131 is too large, the larger the diameter of the rolling element 14, the more the area of the gap is reducedAnd is limited. It is therefore preferred that the diameter d of the rolling elements does not exceed 70 μm, otherwise exceeding 70 μm has no positive effect in practical high-pressure pump applications.

Therefore, it can be seen from the above calculation example that the plunger gap can be greatly reduced by forming the annular groove 131 in the inner bore of the plunger sleeve 13 and filling the rolling elements 14 in the annular groove 131. The difference between the radial depth of the annular groove 131 (i.e., the groove reduction G) and the diameter d of the rolling element is preferably not too large, and is usually preferably controlled to be in the range of 0.5 μm to 5 μm, which is effective in reducing the gap area. That is, the annular groove 131 has a groove gap G with the plunger 12, and when one or more rolling elements 14 are arranged radially, the difference between the groove gap G and the width of the rolling elements 14 filled in the radial direction is preferably 0.5 μm to 5.0 μm.

Further, the gap leakage rate is evaluated according to the annular gap leakage formula, namely:

wherein: q is leakage rate, D is plunger diameter, delta is unilateral gap width, delta P is upper and lower hydraulic pressure difference, L is runner length, C is laminar flow initial section correction coefficient, mu is fluid viscosity coefficient, and C is approximately equal to 1 under most conditions. It can be seen that the leakage rate Q is strongly dependent on Δ P, L, D and δ. The gap leakage rate Q is 3 times the plunger gap. Therefore, the reduction of the gap can greatly improve the problem of oil supply efficiency loss caused by the plunger gap. While other variables Δ P depend on application requirements, decreasing D can decrease Q, but the theoretical volume decreases in a quadratic relationship, and the loss of the theoretical volume can be compensated by increasing the lift, which increases the cost and the volume of the part.

It should be appreciated that the axial ball stack height is also related to the reduction of the gap area, and if the gap area is reduced by 50%, the leakage can be reduced to 0.5^3/0.2 ^ 0.625 even if the ball fills 20% of the height of the annular groove in the axial height. If the gap area is reduced by 90%, even if the ball fills 70% of the height of the annular groove in the axial height, the leakage rate is 0.9^3/0.7 ^ 1.04, and the leakage rate is increased. Therefore, the height of the rolling element array in the axial direction should be set according to the reduction amount of the actual gap area, and the more the gap area is reduced, the larger the margin that the annular groove can be reduced in height. Furthermore, for example, in the prevailing trend in the development of next generation systems, 350bar is raised to 500bar system pressure, which is proportional to the leakage rate, with a leakage increase rate of 3/7 ≈ 1.43 times. The area is related to the leakage rate by the power of 3. Under the condition of not changing D and L, the width of the unilateral gap is reduced by 8.4 percent, namely, the efficiency loss caused by the pressure rise of a system can be compensated, and through the application of the technology disclosed by the invention, the equivalent gap width of the plunger can be easily reduced by 10 to 50 percent, so that the improvement of the oil supply efficiency is higher than the application requirement of the next generation technology.

Similarly, when a plurality of balls are arranged in the radial direction of the annular groove 131, the reduction of the gap area can be calculated in the same manner, and the detailed description is omitted, and the above-mentioned example can be referred to. In general, in the case where the radial direction is a plurality of balls, the filling area of the plurality of balls is the same as that of a single ball.

Further, the design effect of the invention is verified from experimental data. FIG. 7 is a graph of cam rotation speed (in rpm) versus fueling efficiency in non-combustible test oils at 350bar (% Delivery rate), where curve a is the fueling curve for dusty oils and curve b is the fueling curve for clean oils. As shown in FIG. 7, the fueling efficiency of curve a is higher than that of curve b, and particularly, the fueling efficiency is greatly improved at medium and low rotation speeds (e.g. below 500rpm), for example, the fueling efficiency is improved by about 8% at low rotation speed of 250rpm (engine 500rpm), and the fueling efficiency is greatly improved even at cam rotation speed of 2000rpm (engine 4000 rpm). It is understood that a dusty oil is one in which the dust is present in the oil in the form of small particles, and a clean oil is one in which the dust is not included. The problems are all based on the research findings of the inventor in the experiment, the inventor finds that a large number of small particles exist in the oil product, so that a layer of dust small particles are filled in the gap of the plunger after the experiment operation, the oil supply efficiency is greatly improved after the experiment operation, and meanwhile, the movement of the plunger is not influenced by the particles, so that the problem that the oil supply efficiency is seriously reduced when the pressure of the pump oil is higher is solved, and the remarkable effect is achieved.

It should be noted that in the conventional process, the diameter of the ball is usually 100um, while the diameter of the ball of the present invention is usually required to be smaller, such as 5 μm, 10 μm, 12 μm, 16 μm or 70 μm, etc., so as to ensure the compactness of the packing, and the ball is usually a round ball, so that the packing density is better and the ball is not easy to wear. Moreover, the balls can be sand, such as silt with the particle size of 4 um-62 um, and the required particle size and sphericity can be found. The ball may also be made of glass powder, such as quasi-spherical glass powder.

During actual assembly, the plunger 12 can be firstly installed in the plunger sleeve 13, and then the plunger matching part is integrally installed in the pump body 11. For the assembly of the rolling elements 14, as shown in fig. 5 and 6, one end of the plunger sleeve 13 may be first plugged with the plunger 12, a predetermined number of rolling elements 14 may be loaded, the balls accumulated at the head of the plunger may be shaken off into the side grooves, and the plunger 12 may be pushed out from the other end of the plunger sleeve 13.

Further, the embodiment of the present invention also provides a direct fuel injection engine, which includes the high-pressure pump 10 according to the present invention. The advantages of the direct fuel injection engine can be obtained with reference to the above-described technical effects of the high-pressure pump 10. Therefore, the plunger clearance is reduced through the filling of the rolling bodies, the oil pumping efficiency of the high-pressure pump in the operation of the engine in the low-speed area is improved, and the bottleneck problem that the oil pumping efficiency of a next generation fuel direct injection system in the low-speed area is extremely low under higher system pressure (more than 500bar) can be solved. And the processing precision of the plunger can be properly relaxed, and the manufacturing cost is reduced.

It should be understood that the above-described embodiments specifically disclose features of preferred embodiments of the present invention so that those skilled in the art may better understand the present invention. Those skilled in the art will appreciate that the present invention is susceptible to considerable modification based on the disclosure herein, to achieve the same objects and/or achieve the same advantages as the disclosed embodiments of the present invention. Those skilled in the art should also realize that such similar constructions do not depart from the scope of the present disclosure, and that they may make various changes, substitutions and alterations herein without departing from the scope of the present disclosure.

Claims

1. A plunger and barrel assembly is characterized by comprising a plunger, a plunger sleeve and a rolling body; the plunger sleeve is provided with an inner hole which is axially communicated, and the plunger is movably arranged in the inner hole in a penetrating way; an annular groove is formed in the inner circumferential surface of the inner hole between the two ends, and a plurality of rolling bodies are filled in the annular groove; each rolling element is sized to prevent it from entering the plunger gap, and is further configured to be movable within the annular groove.

2. A coupling as claimed in claim 1, wherein the number of said annular grooves is one or more, and a plurality of said annular grooves are provided at intervals along the axial direction of said plunger sleeve.

3. A coupling as claimed in claim 2 wherein the annular recess is a continuous, uninterrupted ring of recesses or is formed by a plurality of sub-recesses symmetrically distributed about the axis of the bore.

4. A plunger and coupling according to any one of claims 1-3, wherein said annular recess is dimensioned to receive a plurality of said rolling elements in an axial direction of said bore, said annular recess also being dimensioned to receive one or more of said rolling elements in a radial direction of said bore.

5. A coupling as claimed in claim 4, wherein a plurality of said rolling elements fill the entire annular groove or fill a portion of the height of the annular groove in the axial direction of the bore.

6. A plunger and matching member according to any one of claims 1-3, characterised in that said rolling bodies are of identical or different construction, including the shape and/or size of the rolling bodies.

7. A plunger and coupling according to any one of claims 1 to 3 characterised in that the rolling elements are regularly or irregularly shaped.

8. A plunger and matching part according to claim 7, wherein said rolling element is in the shape of a circular sphere, and the diameter of said rolling element is greater than 1.0 μm and less than or equal to 100 μm.

9. A plunger and matching part according to any one of claims 1-3, characterized in that the material of said rolling body is a metallic material or an inorganic non-metallic material.

10. A plunger and barrel assembly as claimed in any one of claims 1 to 3 wherein there is a groove clearance gap between said annular groove and said plunger; in the radial direction of the inner hole, the difference between the groove gap and the width filled by the rolling body is 0.5-5.0 μm.

11. A plunger and barrel assembly according to any one of claims 1 to 3 wherein said plunger gap is greater than or equal to 0.5 μm and less than 70 μm.

12. A plunger sleeve for use in a plunger and barrel assembly as claimed in any one of claims 1 to 11.

13. A high pressure pump comprising a pump body and a plunger and barrel assembly as claimed in any one of claims 1 to 11, said plunger and barrel assembly being disposed in said pump body.