EP0375792B1

EP0375792B1 - Adjustable valve spring retainer for internal combustion engine

Info

Publication number: EP0375792B1
Application number: EP88121323A
Authority: EP
Inventors: Alfred Anthony Black
Original assignee: Individual
Current assignee: Individual
Priority date: 1982-03-29
Filing date: 1982-03-29
Publication date: 1995-01-18
Anticipated expiration: 2002-03-29
Also published as: EP0375792A1; DE3280067D1; EP0090105B1; EP0090105A1

Description

This invention relates to valve adjustment means for internal combustion engines having overhead cams or rocker arms and more particularly relates to means for adjustment or compensation for any unwanted gaps arising between the cam shaft and/or rocker arm and the valve stem.
In typical overhead cam engines the valves are operated by a rocker arm pushing on the valve stem or cam shaft pushing on bucket tappets. The rocker arm is usually actuated by a cam located in association herewith. In order to provide for the thermal expansion of the valve stem due to heat created by the fuel combustion within the engine, gaps are usually provided between the valve stem and rocker arm. Hydraulic arrangements for adjusting or compensating for unwanted gaps or gap variations are disclosed in Swiss Patent No. 322762, French Patent Publication FR-A-2476740, and French Patent Publication FR-A-2370858. This last, for example, suggests an hydraulically operable adjuster in the rocker arm (i.e. in the valve stem operating means) to engage directly upon the valve stem, the valve spring being of necessity retained in a wholly separate body. None of these prior art suggestions is considered to provide a wholly appropriate solution.
According to one aspect of this invention there is provided apparatus to compensate for thermal expansion between the stem of a spring-urged valve and the valve stem operation means within an internal combustion engine, said apparatus comprising a retainer for the valve spring and an adjustor to effect said compensation, the adjustor comprising a body serving as part of, or a container for, hydraulically operable adjustment means that in use effect said compensation, characterised in that
the adjustor body serves additionally as the said retainer for the valve spring,
one end of this combined body and valve spring retainer body has a valve stem receipt aperture therein whereby the body is to be removably retained upon the valve stem by a keeper key,
the other, opposite end of the combined body and valve spring retainer is closed by a cap member that is longitudinally adjustable in position with respect to the adjustment means and in use is closely adjacent the valve stem operation means to be urged thereby towards the valve stem,
and in that
said hydraulically operable adjustment means permits restoration of the desired positional relationship between said cap member and said operation means.
Preferably a seal member is positioned in said valve spring retainer between said cap member and said valve stem receipt aperture, and said combined body and valve spring retainer, cap member and seal member form an hydraulic pressure chamber within said combined body and valve spring retainer, said pressure chamber having an open communication into said valve stem receipt aperture which in normal operation is closed by said seal member so as to retain hydraulic fluid under pressure within said hydraulic pressure chamber.
In a preferred embodiment, the cap member is mounted on the open top of said valve spring retainer member, a seal member is positioned in said valve spring retainer between said cap member and said valve stem receipt bore, and said valve spring retainer, cap member and seal member form an hydraulic pressure chamber within said valve spring retainer, said pressure chamber having an open communication into said valve stem receipt bore which in normal operation is closed by said seal member so as to retain hydraulic fluid under pressure within said hydraulic pressure chamber.
Advantageously, said seal member is adapted to be removable from said valve spring retainer member.
Preferably, hydraulic pressure means are provided in said hydraulic pressure chamber for adjustment of the spatial relation of said cap member to said seal member to adjust for said thermal expansion. Preferably said hydraulic pressure means comprises a plunger disposed between said cap member and said seal member in said hydraulic pressure chamber and adapted to increase the fluid pressure within said chamber when said cap member is depressed by said operation means; and further comprises an hydraulic fluid reservoir adapted to supply hydraulic fluid to said chamber.
Advantageously said hydraulic fluid reservoir is located within said plunger and said valve spring retainer further includes a secondary fluid reservoir interconnected to the first-mentioned hydraulic fluid reservoir by at least one aperture in said cap member.
Conveniently said secondary fluid reservoir is provided with an inlet aperture for the entry therein of hydraulic fluid under pressure from the lubricating system of an internal combustion engine.
Preferably said cap member is provided with at least one aperture for passage of lubricating system fluid out of either the first-mentioned hydraulic fluid reservoir or said secondary fluid reservoir, and further means are provided to supply said lubricating system's fluid under pressure through said aperture(s) to lubricate the upper surface of said cap member.
Advantageously the said inlet aperture or each of said apertures permits fluid entry into said secondary fluid reservoir and its supply therefrom via the first-mentioned aperture(s) into said first-mentioned hydraulic fluid reservoir by splashing of said fluid into said first-mentioned aperture(s) by reciprocating motion due to operation of the hydraulic adjustor.
One herein-disclosed embodiment of this invention provides a valve adjustor base and cap member which can be used with hydraulic lifters (for which, since no adjustments are needed, there are no threaded parts between the cap member and the valve spring retainer base). In this embodiment a chamber is provided within the cap member which, when positioned within the valve spring retainer base, is held in position by a semi-circular clip which fits within a groove provided in the upper outer portion of the valve spring retainer base. An hydraulic piston is positioned above a valve stem bushing and has provided therebetween a pre-loaded spring and ball combination for the capture of hydraulic fluid therein upon the downward thrust of the cam or the rocker arm. The piston may be hollowed in its upper portion and have an aperture in its bottom aligned with the ball. The ball operates as an hydraulic valve for the piston, the piston being just above the ball, riding in the bore just above the pressure chamber. When the cap member is depressed, it moves the piston inward toward the centre of its chamber, thereby compressing oil within the pressure chamber which action provides the means for transferring the movement of the cap member to the valve spring retainer base due to the minimal compressibility of the oil therein. Upon the increase of pressure on the device of this embodiment, some oil will leak backwards out of the pressure chamber formed by the hollow in the retainer and the corresponding piston past the piston wall. Back flow through the centre hole of the piston is controlled by the ball which closes off the oil return when the piston compresses the oil, while - at the times when there is no force thereupon - the ball allows oil to enter the pressure chamber below. This hydraulic embodiment has advantages over the current art which incorporates an hydraulic lifter within a separate housing bored into the top of the cylinder head in that it allows a large percentage of this housing or tappet guide to be eliminated except for a small percentage located on opposite sides of the retainer in line with the cam's direction of rotation. This design lessens the cylinder head weight and the friction between the tappet and the tappet guide. The hydraulic embodiment of this invention is held in position by the keeper key on the valve stem and the pressure of the valve spring upwards against the valve spring retainer base. This embodiment simplifies substantially the construction of hydraulic lifters and lessens significantly their weight. A valve stem bushing acts as a seal and prevents the escape of oil fluid from the pressure chamber down along the valve stem. In some embodiments the valve stem bushing can be threaded into its position to prevent its movement out of its seat or can be sealed in position by a circlip or be an inserted cup. In this embodiment a hole can be provided within the valve spring retainer or cap member which would allow oil to circulate therein which would lessen the noise from resonance and act as a reservoir of oil from which the pressure chamber would draw for its proper operation. It should be noted that in this embodiment this is an additional reservoir if the engine should run low on oil, oil would still be provided within the pressure chamber due to its being trapped between the valve spring retainer base and the cap member.
An alternative embodiment of the hydraulic version of this invention utilizes a hardened steel upper cap member with a lower cap member made of aluminium, aluminium-like material or lightweight material having a reservoir defined therein. Below the reservoir is a hardened inverted cup member with an aperture defined therein. A second hardened cup member is placed in the valve spring retainer base and contains a hollow piston member. Within the upwardly facing hollow is the spring cage and ball which control entry of fluid from the reservoir.
By way of non-limiting example, embodiments of this invention will now be described in greater detail with reference to the accompanying drawings of which:

Figure 1: is a perspective cross-sectional view of an exemplary device according to this invention utilising hydraulic lifters; and
Figure 2: is a cross-sectional view of an alternate embodiment of a hydraulically operable device.

In the embodiment of Fig 1 the valve spring retainer base 60 has on its bottom portion a downwardly protruding outer valve spring retaininglip (into which the outer valve spring is engaged), an inner valve spring retainer lip (into which the inner valve spring is engaged), and a valve stem receipt aperture 76 into which the valve stem passes. Aperture 76 is somewhat narrower at its base than at its top and acts to engage the valve stem due to a keeper key inserted into a groove at the top of the valve stem. A central portion 62 of the valve spring retainer base is provided with a valve stem bushing receipt ledge, and with an upwardly directed non-threaded projection 80,82. The valve spring retainer base 60 has an upwardly extending peripheral portion 64 that too is non-threaded. A retainer cap 66 is positioned within the valve spring retainer base and is held in place by retainer clip 68 which fits within groove 70 within the valve spring retainer base 60.
In this first embodiment of Fig 1, a valve stem bushing 72 is located at position 74 above the valve stem receipt bore 76 above which is positioned piston or plunger 78 which rides within pressure chamber 80 formed by projections 82 extending from valve spring retainer base 60. Below the piston or plunger 78 is located ball member 84 and cage 86 with spring member 88 positioned therebelow. At least one aperture 90 can be provided to allow for the entrance of oil into reservoir 81 for the hydraulic actionas described above and one or more apertures 92,93 may be positioned within the valve spring retainer base 60 or cap 66 to allow for the entrance of oil therein.
Illustrated in Figure 2 is a second embodiment of an hydraulic version utilizing hardened cap 191 above lower cap 192 which has a reservoir 94 defined therein with oil entrance aperture 96 to allow oil into the reservoir. This embodiment has adjustment means 106 comprising an inverted hardened cap 100 with an aperture defined therein positioned below the reservoir and an opposed hardened cup 102 positioned above the valve stem receipt bore 101. Within cup 102 is a hollow piston or plunger 104. Within the upward facing hollow portion is a ball 108 aligned with the aperture in the upper cap 100. Below ball 108 is a cage member 110 and a spring 112 which extends to the inside hollow of piston or plunger 104.
It should be noted that there are many advantages to the utilisation of adjustable valve spring retainers embodying this invention beside their being compact and lighter in weight than the structures that accomplish similar functions in the prior art. In the situation where the seal is constructed of a material of a predetermined strength and the bore in which it rests is of the same dimensions as the valve stem receipt bore, the valve stem retainer embodying this invention will advantageously provide a place of movement by its deformation when struck by the valve stem in situations where the engine is over-revved and the valve head is hit by the piston. This destruction or deformation of the bushing dissipates the destructive force, minimizing damage to the vale so that repairs may be made easily to the device embodying this invention without having to pull the head off the engine to reach a damaged valve.

Claims

Apparatus to compensate for thermal expansion between the stem of a spring-urged valve and the valve stem operation means within an internal combustion engine, said apparatus comprising a retainer for the valve spring and an adjustor to effect said compensation, the adjustor comprising a body serving as part of, or a container for, hydraulically operable adjustment means that in use effect said compensation, characterised in that
the adjustor body (60; Fig 2) serves additionally as the said retainer for the valve spring,
one end of this combined body and valve spring retainer (60; Fig 2) body has a valve stem receipt aperture (76;101) therein whereby the body is to be removably retained upon the valve stem by a keeper key,
the other, opposite end of the combined body and valve spring retainer is closed by a cap member (66;191) that is longitudinally adjustable in position with respect to the adjustment means (78,84; 100,102,104,106,108,110,112) and in use is closely adjacent the valve stem operation means to be urged thereby towards the valve stem,
and in that
said hydraulically operable adjustment means (78,84; 100,102,104,106,108,110,112) permits restoration of the desired positional relationship between said cap member (66;191) and said operation means.
Apparatus according to Claim 1, characterised in that a seal member (72; 102) is positioned in said valve spring retainer (60; Fig 2) between said cap member (66;191,192) and said valve stem receipt aperture (76;101), and in that said combined body and valve spring retainer (60; Fig 2), cap member (66; 191,192) and seal member (72;102) form an hydraulic pressure chamber (80; 94) within said combined body and valve spring retainer (60; Fig 2), said pressure chamber (80; Fig 2) having an open communication (74) into said valve stem receipt aperture (76;101) which in normal operation is closed by said seal member (72;102) so as to retain hydraulic fluid under pressure within said hydraulic pressure chamber (80; Fig 2).
Apparatus according to Claim 1 or Claim 2, characterised in that the cap member (66;191,192) is mounted on the open top of said valve spring retainer member (60; Fig 2), a seal member (72; 102) is positioned in said valve spring retainer (60; Fig 2) between said cap member (66;191,192) and said valve stem receipt bore (76;101), and in that said valve spring retainer (60; Fig 2), cap member (66; 191,192) and seal member (72;102) form an hydraulic pressure chamber (80; 94) within said valve spring retainer (60; Fig 2), said pressure chamber (80; Fig 2) having an open communication (74) into said valve stem receipt bore (76;101) which in normal operation is closed by said seal member (72;102) so as to retain hydraulic fluid under pressure within said hydraulic pressure chamber (80; Fig 2).
Apparatus according to Claim 3, characterised in that said seal member (72;102) is adapted to be removable from said valve spring retainer member (60; Fig 2).
Apparatus according to Claim 3 or 4, characterised by hydraulic pressure means (78; 100,104,106,108,110, 112) in said hydraulic pressure chamber (80;94) for adjustment of the spatial relation of said cap member (66;191,192) to said seal member (72;102) to adjust for said thermal expansion.
Apparatus according to Claim 3 or 4, characterised in that said hydraulic pressure means comprises a plunger (78) disposed between said cap member (66) and said seal member (72) in said hydraulic pressure chamber (80) and adapted to increase the fluid pressure within said chamber (80) when said cap member (66) is depressed by said operation means; and further characterised by an hydraulic fluid reservoir (81) adapted to supply hydraulic fluid to said chamber (80).
Apparatus according to Claim 6 characterised in that said hydraulic fluid reservoir (81) is located within said plunger (78) and said valve spring retainer (60) further includes a secondary fluid reservoir inter-connected to the first-mentioned hydraulic fluid reservoir (81) by at least one aperture (90) in said cap member (66).
Apparatus according to Claim 7 characterised in that said secondary fluid reservoir is provided with an inlet aperture (92) for the entry therein of hydraulic fluid under pressure from the lubricating system of an internal combustion engine.
Apparatus according to Claim 8 characterised in that said cap member (66) is provided with at least one aperture (93) for passage of lubricating system fluid out of either the first-mentioned hydraulic fluid reservoir (81) or said secondary fluid reservoir, and further characterised by means to supply said lubricating system's fluid under pressure through said aperture(s) (92 and/or 93) to lubricate the upper surface of said cap member (66).
Apparatus according to Claim 8 or Claim 9, characterised in that the said inlet aperture (92) or each of said apertures (92,93) permits fluid entry into said secondary fluid reservoir and its supply therefrom via the first-mentioned aperture(s) (90) into said first-mentioned hydraulic fluid reservoir (81) by splashing of said fluid into said first mentioned aperture(s) (90) by reciprocating motion due to operation of the hydraulic adjustor.
Apparatus according to any one of Claims 6 to 10, characterised in that:
said cap member(66) is retained by a circlip (68) within an upper portion (70) of said valve spring retainer member (60),
the plunger member (78) has a hollow region in its upper portion to define said first-mentioned reservoir (81) and has an aperture therein below said hollow region,
a ball member (84) is located below said aperture in said plunger member (78),
a cage member (86) is located below said ball member (84), and
a spring member (88) is disposed between the cage member (86) and the seal member (72).
Apparatus according to Claim 1 or Claim 2, characterised in that:
a circlip (68) retains said cap member (66;191,192) within an upper portion (70) of said valve spring retainer member (60; Fig 3),
said cap member (66; 191,192) includes an upper portion (191) of hardened steel-like material and a lower portion (192) of lightweight aluminium-like material and further has a reservoir (94) defined therein with access apertures (96) in said cap member (66; 191,192) to permit entry of oil into said reservoir (94),
the said lower portion (192) of said cap member(66; 191,192) is positioned above said valve stem receipt aperture,
a plunger member (100) of hollow inverted cup-like shape is located within said cap member's lower portion (192), this plunger member having an aperture (106) in its bight wall,
a ball member (108), located by a cage member (110), is disposed below and in alignment with said aperture (106),
a hollow plunger (102) is located below said cage member and in opposing relation to the said plunger member (100) thereabove and such as to provide a seal member, and
a spring member (112) is located between the plunger member (100) and the hollow plunger (102) to act on said cage member (110) and urge the ball member (108) towards said aperture (106).
Apparatus according to Claim 1, characterised by hydraulic plunger means (78; 104) disposed internally of the body member (60; Fig 2) adjacent the cap means (66; 191) to define an hydraulic fluid reservoir (81; 94) between the plunger means (78;104) and the cap means (66;191) such that, in use, depression of the cap means (66;191) by the operation means moves the plunger means (78;104) inwardly to compress fluid held within said reservoir (81;94) and transfer the movement of the cap means (66;191) to the said combined body and valve spring retainer (60; Fig 2) and through the combined body and valve spring retainer (60; Fig 2) to the valve stem.