CN109386334A

CN109386334A - Hydraulic lash adjuster

Info

Publication number: CN109386334A
Application number: CN201710681986.7A
Authority: CN
Inventors: 谢必鲜; 刘琦盛
Original assignee: Schaeffler Technologies AG and Co KG
Current assignee: Schaeffler Technologies AG and Co KG
Priority date: 2017-08-10
Filing date: 2017-08-10
Publication date: 2019-02-26

Abstract

The present invention provides a hydraulic lash adjuster including a housing, a plunger-piston assembly mounted in the housing so as to be movable in an axial direction relative to the housing, an oil supply chamber defined in the plunger-piston assembly, a high-pressure chamber defined between one end of the plunger-piston assembly and one end of the housing, a leakage gap formed between an outer peripheral surface of the plunger-piston assembly and an inner peripheral surface of the housing, and an oil supply hole formed in the housing for supplying lubricating oil to the oil supply chamber. Wherein a deaeration hole is formed in the housing so as to penetrate a wall of the housing, the deaeration hole communicating with the high-pressure chamber via the leakage gap. In the hydraulic lash adjuster of the present invention, because air can be easily discharged through the deaeration hole, the time of the deaeration process can be shortened, and the rigidity of the hydraulic lash adjuster can be maintained.

Description

Hydraulic lash adjuster

Technical Field

The present invention relates to engine accessories, and more particularly to a hydraulic lash adjuster with a deaeration hole.

Background

Fig. 1 is a schematic diagram showing a structure in the vicinity of an engine valve. Shown in fig. 1 are a hydraulic lash adjuster 100 (also referred to as a hydraulic valve lifter), a cam 200, a roller finger rocker arm 500, a valve 300, and a valve seat 400. The hydraulic lash adjuster 100 is a structural element that automatically adjusts the lash between the finger rocker arm 500 and the valve 300 according to the profile of the cam 200 and the engine operating conditions.

Fig. 2 is an axial cross-sectional schematic view illustrating a hydraulic lash adjuster 100 according to the prior art. The hydraulic lash adjuster 100 includes a housing 1, a piston 2, a plunger 4, a check valve 5, and a return spring 6. The case 1 is a substantially cylindrical case with a bottom. The plunger 4 and the piston 2 are fixedly mounted together to form a plunger-piston assembly, inside which an oil feed chamber B is defined. The plunger-piston assembly is mounted in the housing 1 and is movable in the axial direction a relative to the housing 1. A check valve 5 is attached to the lower end of the piston 2 in the housing 1, and a return spring 6 urges the check valve 5 against the lower end of the piston 2. A high-pressure chamber (may also be referred to as a pressure chamber) C is defined between the lower end of the piston 2 and the bottom of the housing 1. In other words, the oil feed chamber B and the high pressure chamber C are divided by the check valve 5.

An oil supply hole 3 is formed in the housing 1. An oil supply hole 7 is formed in the plunger 4. Referring to fig. 1 and 2, during the base circle phase of the cam 200, the valve 300 is closed, the lubricating oil is supplied to the oil supply chamber B through the oil supply hole 3 and the oil supply hole 7, the check valve 5 is opened under oil pressure, and the oil is filled into the high pressure chamber C. The return spring 6 and hydraulic pressure in the supply chamber B and high pressure chamber C urge the plunger 4 against the finger rocker arm 500 to clear the valve train components. When the valve 300 opens, pressure from the cam 200 presses the plunger-piston assembly into the housing 1, the check valve 5 closes and the pressure in the high pressure chamber C rises. Due to the pressure difference between the high pressure chamber C and the oil supply hole 3, the oil is pressed through the leakage gap between the housing 1 and the piston 2. At the end of the valve lift, the pressure at the top of the plunger 4 becomes less than the hydraulic pressure acting on the plunger 4 and the return spring force. Thus, the high pressure chamber C expands. The check valve 5 opens and the leaked oil is refilled.

During the initial stage of engine start, the high pressure chamber C has some air therein. During the filling of the high-pressure chamber C with lubricating oil, air is simultaneously discharged. But because of the oil pressure from the oil supply bore 3, air cannot escape through the oil supply bore 3, the only way being through the leakage gap (see dashed arrows a1, a2 in fig. 2, dashed arrows a1, a2 being added to the slightly right side of the leakage gap between the housing 1 and the piston 2, housing 1 and plunger 4 only to make this notation clearly visible). However, the leakage gap is also filled with oil, so it takes a long time to fill the high-pressure chamber C with oil (that is, it takes a long time to discharge air from the high-pressure chamber C). If there is still some air in the high pressure chamber C, the bulk modulus of the oil will be significantly reduced when the plunger 4 is compressed, because the air is significantly more compressible than the oil, and the high pressure in the high pressure chamber C may cause cavitation problems. This means that the stiffness of the hydraulic lash adjuster 100 is reduced and does not resist the plunger thrust from the finger rocker arm 500 well, not eliminating all lash of the valve train components, which causes noise and impacts on the dynamic performance of the valve train.

Disclosure of Invention

It is an object of the present invention to overcome the above problems in the prior art and to provide a hydraulic lash adjuster capable of quickly removing air from a high pressure chamber.

The present invention provides a hydraulic lash adjuster including a housing, a plunger-piston assembly mounted in the housing so as to be movable in an axial direction relative to the housing, an oil supply chamber defined in the plunger-piston assembly, a high-pressure chamber defined between one end of the plunger-piston assembly and one end of the housing, a leakage gap formed between an outer peripheral surface of the plunger-piston assembly and an inner peripheral surface of the housing, an oil supply hole formed in the housing for supplying lubricating oil to the oil supply chamber,

wherein,

a deaeration hole is formed in the housing through a wall of the housing, the deaeration hole communicating with the high-pressure chamber via the leakage gap.

In at least one embodiment of the present invention, a check valve is provided between the oil feed chamber and the high pressure chamber.

In at least one embodiment of the present invention, the gas purge hole is provided between the oil supply hole and the high pressure chamber in an axial direction of the hydraulic lash adjuster.

In at least one embodiment of the present invention, a groove that communicates the degassing hole with the leakage gap is formed in an inner peripheral surface of the housing.

In at least one embodiment of the present invention, an opening area of the groove is larger than an opening area of the degassing hole.

In at least one embodiment of the present invention, a width of the groove in an axial direction of the hydraulic lash adjuster is larger than a width of the deaeration hole in the axial direction.

In at least one embodiment of the invention, the groove extends along the circumference of the housing (including extending substantially along the circumference of the housing).

In at least one embodiment of the invention, the groove extends over the entire circumference of the housing.

In at least one embodiment of the present invention, a plurality of deaeration holes are in communication with one groove.

In at least one embodiment of the present invention, the plurality of degassing holes are arranged along a circumferential direction of the housing.

In the hydraulic lash adjuster of the present invention, a deaeration hole is formed in the housing so as to penetrate the wall of the housing, and the deaeration hole communicates with the high-pressure chamber via the leakage gap. Since air can be easily discharged through the deaeration hole, the time of the deaeration process can be shortened, and the rigidity of the hydraulic lash adjuster can be maintained.

Drawings

Fig. 1 is a schematic diagram showing a structure in the vicinity of an engine valve.

Fig. 2 is an axial cross-sectional schematic view showing a hydraulic lash adjuster according to the prior art.

FIG. 3 is an axial cross-sectional schematic view illustrating a hydraulic lash adjuster according to one embodiment of the present invention.

Fig. 4 is a partially enlarged view showing the hydraulic lash adjuster in fig. 3.

List of reference numerals

100 hydraulic lash adjusters; 200 cams; 300 air valves; 400 valve seats; 500 roller finger-shaped rocker arm

1, a shell; 2, a piston; 3 an oil supply hole of the shell; 4, a plunger; 5 a check valve; 6, a return spring; 7 oil supply hole of plunger; axial direction A; b, an oil supply chamber; c, a high-pressure chamber;

11, removing air holes; 12 grooves.

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 intended only to teach one skilled in the art how to practice the invention, and is not intended to be exhaustive or to limit the scope of the invention.

Referring to fig. 3 and 4, a hydraulic lash adjuster 100 according to an embodiment of the present invention has substantially the same basic structure as the hydraulic lash adjuster 100 shown in fig. 2, and therefore, the same components as the hydraulic lash adjuster 100 in fig. 2 are denoted by the same reference numerals, and detailed description thereof is omitted.

In the case 1 of the hydraulic lash adjuster 100 of this embodiment, the deaeration hole 11 is provided so as to penetrate the wall of the case 1 in addition to the oil supply hole 3 in the related art. The deaeration hole 11 extends from the outside of the housing 1 to the inside of the housing 1. Further preferably, a groove 12 is provided on the inner peripheral surface of the wall of the housing 1 around the deaeration hole 11.

During the filling of the lubricating oil into the high-pressure chamber C, air can be discharged to the groove 12 and the scavenging hole 11 through a leakage gap between the housing 1 and the piston 2 (see a dotted arrow a1 in fig. 3, a dotted arrow a1 is added to a little right of the leakage gap between the housing 1 and the piston 2 only for the sake of clarity of the notation), and then discharged to the atmosphere. In contrast to the design in fig. 2, air will also be expelled through the leakage gaps between the housing 1 and the piston 2 and the housing 1 and the plunger 4 (see arrows a1 and a2 in fig. 3), which may also be filled with oil. But the deaeration hole 11 is directly connected to the outside of the housing 1, i.e. to the atmosphere, the oil pressure in the groove 12 and the leakage gap between the housing 1 and the piston 2 is smaller than in the design of fig. 2, the groove 12 and the deaeration hole 11 can help to discharge the air significantly. This will thus shorten the time to exhaust air from the high pressure chamber C and maintain the stiffness of the hydraulic lash adjuster 100 to resist plunger thrust from the finger rocker 500, eliminating any lash present in the valve train components, and the noise and other NVH (noise, vibration and harshness) problems can also be addressed.

In this embodiment, the deaeration holes 11 and the grooves 12 are formed in the wall of the housing 1. The deaeration holes 11 are aligned with the leakage gap between the housing 1 and the piston 2. In the axial direction a, the deaeration hole 11 and the groove 12 are provided in the housing 1 at a position between the oil supply hole 3 and the high-pressure chamber C. The deaeration holes 11 and the grooves 12 thus connect the leakage gap and the outside air relatively close to the high-pressure chamber C. In the degassing process, air first comes to the grooves 12 via the leakage gap and then is discharged to the outside of the housing 1 through the degassing holes 11 rather than only through the leakage gap.

The diameter of the deaeration holes 11 is small to prevent too much oil leakage. The width of the groove 12 in the axial direction a of the lash adjuster 100 may be larger than the width of the deaeration hole 11 in the axial direction a. In short, the opening area of the deaeration hole 11 is smaller than the opening area of the groove 12, and the provision of the groove 12 facilitates the entry of air from the leakage gap into the deaeration hole 11, as compared to forming only the deaeration hole 11.

In one non-limiting example, the deaeration holes 11 are cylindrical, the diameter of the deaeration holes 11 may be 1 to 2mm, and the (radial) thickness of the grooves 12 may be 0.1 to 0.3 mm.

The shape other than the air hole 11 may be other than a cylindrical shape. The number of the deaeration holes 11 may be one or more, depending on the size of the leakage gap and the stiffness of the hydraulic lash adjuster 100.

For example, in the case where a plurality of the degassing holes 11 are provided, the plurality of degassing holes 11 may be provided at different axial and/or circumferential positions of the casing 1, and at the same time, one or more grooves 12 may be provided corresponding to the plurality of degassing holes 11.

Preferably, two or more degassing holes 11 communicate with the same groove 12, which may simplify the machining of the groove 12. For example, at least one groove 12 may extend substantially along the circumferential direction of the housing 1, and may extend over the entire circumference (360 degrees) of the housing 1, and a plurality of deaeration holes 11 may be provided along the circumferential direction of the housing 1 to communicate with the groove 12.

A brief summary of some of the technical effects that can be achieved by the hydraulic lash adjuster 100 of the present invention follows.

(1) Since the air can be easily discharged through the degassing holes 11, the time of the degassing process can be shortened.

(2) The stiffness of the hydraulic lash adjuster 100 may be maintained and the lash of the valve train components may be automatically adjusted.

(3) High dynamic performance of the valve train can be achieved by the hydraulic lash adjuster 100, solving the NVH problem of the hydraulic lash adjuster 100.

(4) Since the collision between the valve and the valve seat is eliminated, the durability and reliability of the valve mechanism are improved.

(5) The power performance of the engine and the fuel consumption in the initial stage of the starting of the engine are obviously improved.

It should be understood that the above embodiments are only exemplary and are not intended to limit the present invention. Various modifications and alterations of the above-described embodiments may be made by those skilled in the art in light of the teachings of the present invention without departing from the scope thereof.

(1) It will be appreciated that the plunger 4 and piston 2 may be manufactured separately from one another and then assembled together to form a plunger-piston assembly. However, the plunger-piston assembly of the present invention includes an embodiment in which the plunger and the piston are integrally formed. That is, the plunger-piston assembly of the present invention may also include or be referred to as a plunger alone.

(2) It will be appreciated that the grooves 12 serve to make it easier for air to enter the deaeration holes 11 from the leakage gap. However, in the present invention, the groove 12 may be omitted so that the deaeration hole 11 directly communicates with the leakage gap.

(3) The deaeration hole 11 may extend in the radial direction R of the hydraulic lash adjuster 100, however, the present invention is not limited thereto.

(4) The opening area of the deaeration holes 11 can be varied. For example, the deaeration hole 11 may be formed in a bell mouth shape such that a smaller opening thereof is directed to the outside of the housing 1 and a larger opening is directed to the piston 2.

The opening area of the deaeration holes 11 or the opening area of the grooves 12 may be defined as follows: a cylindrical surface passing through the deaeration hole 11 or the groove 12 is virtually made around the center axis of the hydraulic lash adjuster 100, and the area of the deaeration hole 11 or the groove 12 cut by the cylindrical surface is the opening area of the deaeration hole 11 or the groove 12.

Claims

1. A hydraulic lash adjuster including a housing, a plunger-piston assembly mounted in the housing so as to be movable in an axial direction relative to the housing, an oil supply chamber being defined in the plunger-piston assembly, a high-pressure chamber being defined between one end of the plunger-piston assembly and one end of the housing, a leakage gap being formed between an outer peripheral surface of the plunger-piston assembly and an inner peripheral surface of the housing, an oil supply hole being formed in the housing for supplying lubricating oil to the oil supply chamber,

it is characterized in that the preparation method is characterized in that,

2. The hydraulic lash adjuster according to claim 1, wherein a check valve is provided between the oil feed chamber and the high pressure chamber.

3. The hydraulic lash adjuster according to claim 1, wherein the gas purging hole is provided between the oil supply hole and the high pressure chamber in an axial direction of the hydraulic lash adjuster.

4. The hydraulic lash adjuster according to claim 1, wherein a groove that communicates the scavenging hole with the leakage gap is formed in an inner peripheral surface of the housing.

5. The hydraulic lash adjuster according to claim 4 wherein the open area of the groove is greater than the open area of the deaeration hole.

6. The hydraulic lash adjuster according to claim 4, wherein a width of the groove in an axial direction of the hydraulic lash adjuster is larger than a width of the scavenging hole in the axial direction.

7. The hydraulic lash adjuster according to claim 4 wherein the groove extends circumferentially of the housing.

8. The hydraulic lash adjuster according to claim 7 wherein the groove extends over the entire circumference of the housing.

9. The hydraulic lash adjuster according to claim 4 wherein a plurality of deaeration holes are in communication with one groove.

10. The hydraulic lash adjuster according to claim 9 wherein the plurality of deaeration holes are arranged along a circumferential direction of the housing.