Columnar hydraulic tappet

Abstract

A columnar hydraulic tappet comprises a housing, in which a plunger is correspondingly mounted. A high-pressure chamber extends between a lower end surface of the plunger and a lower side of the housing. An outer ring groove is disposed on the outer diameter of the housing, an inner ring groove is disposed in the radial inner side of the housing, and housing oil feed holes are disposed between the inner ring groove and the outer ring groove. The lower end inside the housing is provided with a grinding wheel groove, an upper end wall of the inner ring groove of the housing is a first internal cylindrical wall, and a housing inner-wall between the lower end of the inner ring groove of the housing and the grinding wheel groove is a second internal cylindrical wall.

Claims

1. A columnar hydraulic tappet, comprising a housing, wherein a plunger that axially moves relatively to the housing is correspondingly mounted in the housing, a high-pressure chamber for a hydraulic medium extends between a lower end surface of the plunger and a lower side of the housing, and the high-pressure chamber can be sealed by means of a check valve adapted to open towards the high-pressure chamber; an outer ring groove for hydraulic medium circulation is disposed on an outer diameter of the housing, an inner ring groove for hydraulic medium circulation is disposed in a radial inner side of the housing, and one or more housing oil feed holes are disposed between the inner ring groove and the outer ring groove; a lower end inside of the housing is provided with a grinding wheel groove, an upper end wall of the inner ring groove of the housing is a first internal cylindrical wall, and a housing inner-wall between a lower end of the inner ring groove of the housing and the grinding wheel groove is a second internal cylindrical wall; a lower part of a head of the plunger is provided with a first ring groove and a middle part of the plunger is provided with a second ring groove; a plunger middle wall is disposed between the first ring groove and the second ring groove, where the second ring groove is a concave and wide ring groove, the plunger middle wall is provided with at least one oil feed hole communicated with the second ring groove, a cylindrical wall at a lower end of the concave and wide ring groove of the plunger is a plunger lower wall, and a leak-down sealing region is disposed between the second internal cylindrical wall of the housing and the plunger lower wall; and a width of the grinding wheel groove is not less than a working stroke height h of the plunger.

2. The columnar hydraulic tappet according to claim 1, wherein a length a of the plunger lower wall of the plunger is not less than a sum of the width of the grinding wheel groove and a length L of the leak-down sealing region, i.e., a+L.

3. The columnar hydraulic tappet according to claim 1, wherein when the plunger is at a working height, an upper end of the grinding wheel groove of the housing is not lower than the lower end surface of the plunger.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a schematic structural diagram of a hydraulic tappet in the prior art when it is at a working height.

(2) FIG. 2 is a schematic structural diagram of a hydraulic tappet in the prior art when it is at the minimum compression height.

(3) FIG. 3 is a schematic structural diagram of a hydraulic tappet according to an embodiment of the present invention when it is at a working height.

(4) FIG. 4 is a schematic structural diagram of a hydraulic tappet according to an embodiment of the present invention when it is at the minimum compression height.

DRAWING NUMBER DESCRIPTION

(5) 1 plunger

(6) 2 housing

(7) 3 check valve

(8) 4 reset spring

(9) 5 concave and wide ring groove of the plunger

(10) 6 oil feed hole of the plunger

(11) 7 oil hole of the housing

(12) 8 inner ring groove of the housing

(13) 9 oil storage chamber

(14) 10 high-pressure chamber

(15) 11 head of the plunger

(16) 12 outer ring groove of the housing

(17) 13 plunger neck (first ring groove)

(18) 14 grinding wheel groove of the housing

(19) 15 plunger lower wall

(20) 16 first internal cylindrical wall of the housing

(21) 17 second internal cylindrical wall of the housing

(22) 18 leak-down sealing region

(23) 19 limiting clamp spring

DETAILED DESCRIPTION OF THE EMBODIMENTS

(24) The following further describes the present invention with reference to the accompanying drawings.

Embodiment 1

(25) As shown in FIG. 4, a columnar hydraulic tappet for a valve mechanism of an engine has a can-shaped housing 2. In the housing 2, there is provided with a plunger 1 that can axially slides. A high-pressure chamber 10 is disposed between a lower end surface of the plunger 1 and the housing 2, and the high-pressure chamber 10 can be sealed by means of a check valve 3 positioned at the lower end of the plunger 1, and the high-pressure chamber 10 has a reset spring 4 connected with the plunger 1 and the housing 2. An outer ring groove 12 of the housing for hydraulic medium circulation is disposed on the outer diameter of the housing 2, an inner ring groove 8 of the housing for hydraulic medium circulation is disposed in the radial inner side of the housing 2, and one or more oil holes 7 for hydraulic medium circulation are disposed between the inner ring groove 8 of the housing and the outer ring groove 12 of the housing; an upper end inner-wall of the inner ring groove 8 of the housing is a first internal cylindrical wall 16, a lower end inner-wall of the inner ring groove 8 of the housing is a second internal cylindrical wall 17 of the housing, and at the lower end of the second internal cylindrical wall 17 of the housing there is provided with a grinding wheel groove 14 convenient for blind hole processing. On the outer diameter of the plunger 1 there is provided with a concave and wide ring groove 5 for hydraulic medium circulation, on a vertical wall of the plunger above the concave and wide ring groove 5 there is provided with one or more circumferentially distributed plunger oil feed holes 6, the inner ring groove 8 of the housing is communicated with the concave and wide ring groove 5 of the plunger, and the concave and wide ring groove 5 of the plunger is communicated with the plunger oil feed holes 6. The hydraulic medium enters from the outer ring groove 12 of the housing to the oil storage chamber 9 of the plunger. Between the concave and wide ring groove 5 of the plunger and the inner ring groove 8 of the housing there is provided with a limiting clamp spring 19. A leak-down sealing region 18 for leaking the hydraulic medium is formed between the plunger lower wall 15 and the second internal cylindrical wall 17 of the housing by fitting. At the lower end of the head 11 of the plunger there is provided with an inwardly dished neck 13, i.e., the first ring groove. The neck 13 plays a role in facilitating installation of a lock piece, through which the neck is reliably connected with the roller rocker arm, to prevent a falloff.

(26) As shown in FIG. 3 and FIG. 4, the plunger has a one-piece structure, good in guiding, simple in processing technology and convenient for assembly.

(27) The width of the grinding wheel groove of the housing is , the working stroke of the hydraulic tappet is h, according to a test result, h.

(28) The length dimension a of the plunger lower wall of the plunger is larger and is not less than a sum of the width of the grinding wheel groove and a length L of the leak-down sealing region, i.e., a+L.

(29) When the hydraulic tappet is at a working height, the upper end of the grinding wheel groove of the housing is not less than the lower end surface of the plunger. In the process when the plunger runs from the working height to the minimum compression height, the length L of the leak-down sealing region formed between the plunger lower wall and the second internal cylindrical wall of the housing by fitting remains unchanged basically, L is approximately equal to the length of the second internal cylindrical wall of the housing, thereby improving the leak-down stability of the hydraulic tappet in the whole working stroke.