CN212716921U

CN212716921U - Piston with pressure balance hole and engine

Info

Publication number: CN212716921U
Application number: CN202021856908.XU
Authority: CN
Inventors: 曾少波; 马振飞; 宋德锋
Original assignee: Mahle Automobile Technology China Co ltd
Current assignee: Mahle Automobile Technology China Co ltd
Priority date: 2020-08-31
Filing date: 2020-08-31
Publication date: 2021-03-16
Anticipated expiration: 2030-08-31

Abstract

The utility model provides a take piston and engine in pressure balance hole, the piston is used for the engine, the perisporium of piston is formed with the annular, the annular is used for holding the piston ring, the perisporium of piston still partly to the indent and then form one or more pressure balance hole, the pressure balance hole does not pierce through the lateral wall of piston in the axial of piston, the pressure balance hole is compared the annular is close to the combustion chamber of the cylinder of engine, just the pressure balance hole with the annular is linked together. According to the utility model discloses a take piston structure in pressure balance hole is simple and can reduce the blowby phenomenon in the cylinder.

Description

Piston with pressure balance hole and engine

Technical Field

The utility model relates to an engine field, more specifically relate to a take piston in pressure balance hole and including engine of this piston for engine.

Background

With the increasingly strict requirements on the exhaust emission of the motor vehicle, the fuel consumption of the motor vehicle under the comprehensive working condition is expected to be lower than a certain limit value, and the engine oil consumption and the blow-by gas quantity are important indexes influencing the fuel consumption.

The engine works by sucking mixed gas, compressing the mixed gas and igniting the compressed gas to do work to generate power. In the process from compression to combustion, high pressure is generated in the cylinder, and the compressed gas can blow out from the gap between the piston and the cylinder body, the opening of the piston ring, the gap between the piston ring and the cylinder body, and the like and enter the crankcase, which is called blow-by phenomenon.

When the blow-by amount is too large, the power torque of the engine cannot reach a preset value, the power output is reduced, and the fuel consumption is increased; in addition, the temperature of the piston and the piston ring is also increased, and the failure probability of parts is increased; the blow-by gas also easily causes the lubricating oil on the ring groove and the ring to be ablated and bonded to form carbon deposition, and the lubricating condition is deteriorated to aggravate the abrasion of the machine parts. Gas blow-by into the crankcase also accelerates oil deterioration and corrosion of the components. The oil consumption is increased by the increase of the crankcase pressure.

The piston compression ring (hereinafter referred to as piston ring) can keep the sealing between the piston and the cylinder wall, and the blow-by gas quantity is controlled in a small range so as to improve the heat efficiency of the engine.

The force acting on the piston ring includes gas pressure, ring self-elasticity, inertia force of reciprocating motion of the ring, friction force between the ring and the cylinder and the ring groove, and the like. Due to the action of these forces, the movements of the piston ring during the reciprocating movement of the piston include axial movements, radial movements and gyratory movements, which are the basic movements of the piston ring.

However, the superposition of the various forces and motions described above can also result in undesirable irregular motion of the piston ring, including axial irregular motion (including levitation and axial vibration), radial irregular motion, vibration and twisting motion, and the like. These irregular movements play a limiting role in the normal operation of the piston ring.

Fig. 1 shows a possible partial structure of a piston equipped with piston rings. A plurality of ring grooves are generally formed in the circumferential wall of the piston 10, and a ring groove 11 near the top of the piston (or near the combustion chamber) in the axial direction a of the piston 10 is generally referred to as a first ring groove (hereinafter, also simply referred to as a ring groove), and a piston ring 20 is fitted into the ring groove 11. The piston ring 20 in this ring groove 11 is subjected to the maximum gas pressure during engine operation, compared to piston rings provided in other ring grooves.

Although the piston ring 20 has an initial spring force that helps the piston ring 20 to abut against the cylinder liner C, when the engine is in a power stroke, the gas pressure generated by combustion is very high, and the contact surface pressure between the piston ring 20 and the cylinder liner C generated by the initial spring force of the piston ring 20 is not sufficient to ensure a good seal of the piston ring 20 and the cylinder liner C.

One possible way to solve the problem of sealing the piston ring 20 is to introduce high pressure gas into the back of the piston ring to push the piston ring 20 against the cylinder liner C.

The side surface of the ring groove 11 closer to the piston crown portion in the axial direction a is referred to as an upper side surface 111, the side surface of the ring groove 11 farther from the piston crown portion in the axial direction a is referred to as a lower side surface 112, and the side surface of the ring groove 11 located on the inner peripheral portion is referred to as a bottom surface 113. The gap formed between the piston ring 20 and the upper side 111 is referred to as a side gap G2, and the gap formed between the piston ring 20 and the bottom surface 113 is referred to as a back gap G3.

In the power stroke of the engine, the piston ring 20 is attached to the lower side surface 112 under the action of gas pressure, combustion gas enters the back gap G3 through the firepower bank gap G1 and the side gap G2, and the gas pressure in the back gap G3 can generate radial thrust towards the periphery of the piston ring 20, so that the contact pressure between the piston ring 20 and the cylinder sleeve C is increased, and a better sealing effect is achieved.

However, since the backlash G2 is small, it takes a certain time for gas to enter the backlash G3 through the backlash G2 and to form a sufficient pressure, during which a blow-by phenomenon easily occurs between the piston ring 20 and the cylinder liner C.

SUMMERY OF THE UTILITY MODEL

An object of the utility model is to overcome or alleviate the not enough of above-mentioned prior art existence at least, provide the less piston in pressure balance hole of taking of air blowby volume.

According to a first aspect of the present invention, there is provided a piston with a pressure balance hole, the piston being used in an engine, a circumferential wall of the piston being formed with a ring groove for accommodating a piston ring, wherein,

the peripheral wall of the piston is partially recessed to form one or more pressure balance holes, the pressure balance holes do not penetrate through the side wall of the piston, the pressure balance holes are closer to a combustion chamber of a cylinder of the engine than the ring groove in the axial direction of the piston, and the pressure balance holes are communicated with the ring groove.

In at least one embodiment, a back clearance is left between a bottom surface of the ring groove located radially inward and the piston ring, and the pressure balance hole directly communicates with the back clearance.

In at least one embodiment, the ring groove is provided with a backlash between a side wall of the combustion chamber in the axial direction and the piston ring, and the pressure balance hole is also communicated with the backlash.

In at least one embodiment, the pressure balance hole is plural, and plural pressure balance holes are distributed in the circumferential direction of the piston.

In at least one embodiment, an axis of the pressure balance hole is parallel to an upper side of the ring groove that is close to the combustion chamber in the axial direction; or

The axis of the pressure balance hole and the upper side surface of the ring groove, which is close to the combustion chamber in the axial direction, form an included angle of not more than 20 degrees.

In at least one embodiment, the peripheral wall of the pressure equalizing hole is a portion of a cylindrical surface.

In at least one embodiment, the difference between the depth of the pressure balance hole and the depth of the ring groove in the radial direction of the piston is not more than 3 mm.

In at least one embodiment, the width of the ring groove in the axial direction increases further outward in the radial direction of the piston.

In at least one embodiment, the ring groove is a first ring groove for mounting the piston ring closest to the combustion chamber in the axial direction.

According to the utility model discloses a second aspect provides an engine, and it includes cylinder, piston and piston ring, its characterized in that, the piston is according to the utility model discloses a piston, the piston ring inlays to be located the piston in the annular, the piston set up in the cylinder.

According to the utility model discloses a take piston structure in pressure balance hole is simple and can reduce the blowby phenomenon in the cylinder.

According to the utility model discloses an engine has same advantage.

Drawings

Fig. 1 is a sectional view of a possible partial structure of a piston with piston rings mounted thereon.

Fig. 2 is a schematic structural view of a piston according to an embodiment of the present invention.

Fig. 3 is a front view of the piston shown in fig. 2.

Fig. 4 is a sectional view of the piston shown in fig. 3 taken along a-a direction.

Fig. 5 is a sectional view of a partial structure of a piston according to an embodiment of the present invention.

Fig. 6 is a schematic diagram of a piston with piston rings installed therein being subjected to high pressure gas in accordance with an embodiment of the present invention.

Description of reference numerals:

c, cylinder sleeve; 10 a piston; 11, a ring groove; 12 pressure balance holes; 111 an upper side; 112 lower side faces; 113 a bottom surface;

g1 firepower bank gaps; g2 backlash; g3 backlash; axial direction A; r is radial.

Detailed Description

Exemplary embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood that the detailed description is only intended to teach one skilled in the art how to practice the invention, and is not intended to exhaust all possible ways of practicing the invention, nor is it intended to limit the scope of the invention.

A piston with a pressure balance hole according to an embodiment of the present invention will be described with reference to fig. 2 to 6. Referring to fig. 3, 5 and 6, a denotes an axial direction of the piston and R denotes a radial direction of the piston, unless otherwise specified. And the positional relationships of the respective parts are explained by the vertical relationships shown in fig. 3, 5 and 6, it should be understood that the vertical positional relationships of the respective parts in the present invention are relative, and the position coordinates can be spatially rotated according to the actual application of the device.

Fig. 2 to 4 show the structure of the piston 10 of the present embodiment at different viewing angles. The circumferential wall portion of the piston 10 is formed with a plurality of annular grooves that are arranged in the axial direction a so as to be recessed radially inward, and the present embodiment focuses on the ring groove 11 that is located near the top of the piston (i.e., the upper portion of the piston 10 in the drawing, or near the combustion chamber) in the axial direction a, and this ring groove 11 is also referred to in the industry as a first ring groove. During engine combustion work, the piston rings 20 in this ring groove 11 (see also fig. 6) will experience the greatest pressure from the gases in the combustion chamber compared to the piston rings in other ring grooves away from the top of the piston.

The circumferential wall of the piston 10 is partially recessed radially inward to form a plurality of (8 in the present embodiment) pressure balance holes 12, and the pressure balance holes 12 are communicated with the ring groove 11, and the pressure balance holes 12 are closer to the combustion chamber than the ring groove 11 in the axial direction a. The pressure balance hole 12 does not penetrate the side wall of the piston 10.

In the present embodiment, the plurality of pressure balance holes 12 are evenly distributed in the circumferential direction of the piston 10. It should be understood that such a uniform distribution of the plurality of pressure balance holes 12 in the circumferential direction is not essential, for example, the plurality of pressure balance holes 12 may be non-uniformly distributed in the circumferential direction, or in an extreme case, only 1 pressure balance hole 12 may be provided.

The pressure balance hole 12 is formed, for example, by drilling, for example, after the ring groove 11 is formed, a blind hole is drilled above the ring groove 11 in the axial direction a near the top of the piston using a drill. The pressure balance hole 12 is preferably formed such that the peripheral wall thereof is a part of a cylindrical surface, and the pressure balance hole 12 is simple to manufacture and does not easily cause stress concentration of the piston 10 in the vicinity of the pressure balance hole 12.

The depth of the pressure balance hole 12 is substantially equal to the depth of the ring groove 11 in the radial direction R of the piston, and when the depth of the pressure balance hole 12 is slightly larger or smaller than the depth of the ring groove 11, it is preferable that the difference between the depth of the pressure balance hole 12 and the depth of the ring groove 11 is not larger than 3mm (and more preferably not larger than 1mm) to ensure the structural strength while ensuring a sufficient intake amount of the pressure balance hole 12.

Alternatively, referring to fig. 5, the axis of the pressure balance hole 12 is perpendicular to the axis of the piston 10.

Alternatively, the axis of the pressure balance hole 12 may not be perpendicular to the axis of the piston 10, and the axis of the pressure balance hole 12 is closer to the piston crown than the radially outer side of the piston 10. The arrangement mode can ensure that the edge of the pressure balance hole 12 is not easy to generate sharp corners and stress concentration in the drilling process. Preferably, the axis of the pressure equalizing hole 12 forms an angle of not more than 20 ° with the upper side 111 of the ring groove 11 in the axial direction a near the top of the piston.

Preferably, in the present embodiment, the cross section of the ring groove 11 in the axial direction a is trapezoidal, and the width of the ring groove 11 in the axial direction a increases as it goes radially outward of the piston 10. The two side faces of the ring groove 11 facing opposite in the axial direction a are each arranged obliquely with respect to the top of the piston 10 in such a manner as to reduce the carbon deposition in the ring groove 11. In correspondence with such ring groove 11, optionally, the axis of the pressure balance hole 12 is parallel to the upper side 111 of the ring groove 11 in the axial direction a near the top of the piston, which both facilitates the formation of the pressure balance hole 12 and makes the edge of the pressure balance hole 12 less prone to stress concentration.

Next, the function of the piston with the pressure balance hole according to the present invention in reducing blow-by in the cylinder will be described with reference to fig. 6. It is understood that the broken line in fig. 6 shows a partial boundary of the ring groove 11 when the pressure balance hole 12 is not provided.

For example, during the power stroke of the engine, high-pressure combustion gas (hereinafter referred to as high-pressure gas) from the combustion chamber causes the piston ring 20 to abut against the lower side 112 of the ring groove 11, which is away from the piston crown in the axial direction a. A side gap G2 is formed between the piston ring 20 and the upper surface 111 of the ring groove 11, and a back gap G3 is formed between the piston ring 20 and the bottom surface 113 of the ring groove 11 at the inner peripheral portion. High pressure gas may enter the back gap G3 to create a radial push against the piston ring 20. The high-pressure gas entering the back gap G3 acts on the piston ring 20, applying a force to the piston ring 20 toward the radially outer side, so that the piston ring 20 is more closely attached to the cylinder liner C.

In the present invention, the pressure balance hole 12 is directly communicated with both the side gap G2 and the back gap G3. Direct communication here includes the pressure balance hole 12 communicating directly with the backlash G2 and the backlash G3 without any other structure or passage, e.g., referring to fig. 6, the pressure balance hole 12 may be connected directly to the backlash G2 on the one hand, thereby increasing the size of the backlash G2 in the axial direction a, and on the other hand, the pressure balance hole 12 may be connected directly to the backlash G3 without the backlash G2, thereby increasing the cross-sectional area of the entire passage of the high-pressure gas into the backlash G3, thereby facilitating the high-pressure gas to reach the backlash G3 quickly.

In the structure of fig. 6, it can be considered that the provision of the pressure balance hole 12 simultaneously increases both the backlash G2 and the backlash G3 at the pressure balance hole 12. However, the present application is not limited thereto, and for example, the pressure balance hole 12 may also be formed not integrally with the backlash G2 but separately from the backlash G2 to form a passage to the backlash G3.

High pressure gas may enter the back gap G3 via two paths.

The first path is a conventional path in which combustion gas passes through a fire land gap G1 between the piston ring 20 and the cylinder liner C into a side gap G2 and then into a back gap G3 in a region of the piston 10 that does not have the pressure balance hole 12 in the circumferential direction.

The second path is a fast path (the hollow arrow in fig. 6 shows this path) newly added according to the present invention, and in the region having the pressure balance hole 12 in the circumferential direction of the piston 10, the combustion gas enters the pressure balance hole 12 and the side gap G2 (it can also be considered that the pressure balance hole 12 also constitutes a part of the side gap G2) through the fire land gap G1 between the piston ring 20 and the cylinder liner C, and then enters the back gap G3.

The pressure balance hole 12 enlarges the flow path of the combustion gas, so that the combustion gas can enter the back clearance G3 more quickly, the back pressure of the piston ring 20 is built up in a shorter time, and the sealing state between the piston and the cylinder is brought into a faster state, so that the air blowby of the engine is reduced.

It should be understood that the present invention also provides an engine including the piston.

The utility model discloses at least, one of following advantage has:

(i) according to the utility model discloses a piston simple structure can establish the sealed between piston and the cylinder liner fast in engine working process (especially in the power stroke).

(ii) According to the utility model discloses a piston preparation is convenient, and is with low costs.

Of course, the present invention is not limited to the above embodiments, and those skilled in the art can make various modifications to the above embodiments of the present invention without departing from the scope of the present invention. For example: the utility model discloses do not do the restriction to the concrete shape of annular and the concrete shape of piston ring.

Claims

1. A piston with a pressure balancing hole, the piston being used in an engine, a circumferential wall of the piston being formed with a ring groove for receiving a piston ring, characterized in that,

2. The piston with the pressure balance hole as defined in claim 1, wherein a back clearance is left between a bottom surface of said ring groove located radially inward and said piston ring, and said pressure balance hole is directly communicated with said back clearance.

3. The piston as set forth in claim 2 wherein said ring groove is provided with a side clearance between a side wall of said ring groove adjacent to said combustion chamber in said axial direction and said piston ring, said pressure balance hole being in communication with said side clearance.

4. The piston with the pressure balance hole as claimed in claim 1, wherein the pressure balance hole is plural, and plural pressure balance holes are distributed in a circumferential direction of the piston.

5. The piston with the pressure balance hole as recited in claim 1, wherein an axis of the pressure balance hole is parallel to an upper side of the ring groove which is close to the combustion chamber in the axial direction; or

6. The piston with the pressure balance hole as set forth in claim 1, wherein the difference between the depth of said pressure balance hole and the depth of said ring groove is not more than 3mm in the radial direction of said piston.

7. The piston with the pressure balance hole as recited in any one of claims 1 to 6, wherein the ring groove is a first ring groove for mounting the piston ring closest to the combustion chamber in the axial direction.

8. An engine comprising a cylinder, a piston and piston rings, wherein the piston is according to any one of claims 1 to 7, the piston rings are embedded in the ring grooves of the piston, and the piston is disposed in the cylinder.