US2962012A - Horizontally operable hydraulic valve lifter - Google Patents

Description

- Nov. 29, 1960 P. w. HOWSON 2,962,012

HORIZONTALLY OPERABLE HYDRAULIC VALVE LIFTER Filed Def;v 28, 1959 15 If 12 5f 142' 32 1 1 a v 2 Z 9 I INVENTOR.

fl b7/jrzdson AT'T RNEY HORIZONTALLY OPERABLE HYDRAULIC VALVE LIFTER Phillip W. Howson, Grand Rapids, Mich., assignor to General Motors Corporation, Detroit, Mich., a corporation of Delaware Filed Dec. 28, 1959, Ser. No. 862,251

Claims. (Cl. 123-90) This invention relates to externally fed hydraulic valve lifters and the like in the form of a dashpot device wherein the plunger is hollow and serves as a reservoir for the externally fed fluid, and particularly to such devices which operate in a substantially horizontal direction.

In horizontal or substantially horizontal operation of hydraulic valve lifters, particularly those in which the fluid supply to the plunger reservoir is from an external source as by way of communicating ports in the dashpot cylinder and plunger, a problem exists in preventing the fluid from draining out of the plunger reservoir chamber when the engine is stopped, cutting off the external fluid supply. While it is old in the art to internally baffle the plungers of such lifters which operate at substantial inclination from vertical, as in V-type engines, this does not take care of the aforementioned problem because even with the reservoir inlet aperture in the baffle located centrally thereof there is nothing to prevent reverse flow through the baffle aperture when the lifter is operated at greater inclinations which place the baflle aperture at or nearly at the same vertical level as the pressure chamber inlet from the reservoir. It is also old in the art to mechanically key either the lifter cylinder or the plunger against rotation, but this creates additional problems in increased friction, etc.

My invention solves this reservoir leakage problem in a very simple and eflicient manner which only very slightly increases the cost of the lifter over that of conventional designs intended for substantially upright operation. In its broadest aspects, my invention amounts to providing check valve means to prevent reverse flow through the reservoir supply passage from the exterior of the lifter.

*Following is a more detailed description of the means for carrying out this objective, having reference to the drawing wherein:

Figure 1 is a fragmentary sectional view through the valve lifter guide bore of an internal combustion engine showing one form of my improved valve lifter installed therein in operative relation between the usual driving cam and driven push rod,

Figure 2 is a sectional view taken substantially on line 2-2 of Figure 1.

The hydraulic valve lifter is designated generally by the numeral 1 and includes a rather conventional, generally cup-shaped dashpot or cylinder member formed of a tube 2 closed at one end by a foot piece 3. Shown also is the conventional engine driven cam 4 operatively engaging the foot piece 3. The outer periphery of the tube 2 is rotatably and slidably guided in the lifter bore 5 of the engine crankcase or other fixed part 6 of the engine. The cylinder is open at its opposite end 7, and rotatably and slidably fitting the bore 8 of the tube is a generally cup-shaped or hollow plunger 9. The two cupshaped members are thus slidably interfitted in nesting relation, with the end wall 10 of the plunger and the cyl- 2,962,012 Patented Nov. 29, 1960 inder end wall or foot piece 3 forming between them a fluid pressure chamber 11. The internal side walls and end wall 10 of the plunger define a reservoir chamber 12' for storage of fluid required to replenish the pressure chamber 11 for that which escapes therefrom by leakage past the plunger in operation. Passage means providing a connection between these two chambers for accommodating fluid flow from the reservoir chamber into the pressure chamber, while restraining fluid flow therebetween in the opposite direction, is illustrated in the conventional form of a ball check valve 13 controlling the passage l4 in the end wall of the plunger. Fluid may thus be trapped in the pressure chamber for trans-' mitting thrust from the lifter cylinder to the plunger 9 when movement of the lifter cylinder is effected by the cam The plunger return spring 15 acts in compression to bias the plunger outwardly of the lifter cylinder at all times, thereby tending to maintain the pressure chamber volume at a maximum at all times. Mounted on the open end of the plunger is a conventional push rod seat 16 for a push rod 17 which transmits the cam induced plunger motion to the engine valve or other engine part to be actuated by the cam.

Suitable external fluid supply means for the lifter is provided, including a gallery 22 which may be connected to the engine lubricating pump (not shown), this gallery 22 being open to the lifter bore 5 in the engine. Passage means for connecting this external fluid supply to the plunger reservoir 12 will now be described. The lifter cylinder is provided with an annular external groove 24 of suflicient width to have continuous registry with the gallery 22, and this grooveis connected by a port 23 with an internal groove 25 in the bore 8 of the cylinder. The plunger, in turn, has a side port 26 extending therethrough below the push rod seat 16 and registering continuously with the cylinder internal groove 25 via an annular external groove 21 on the plunger. In order that the fluid (engine oil) thus entering the plunger to fill the reservoir 12 during engine operation will not drain out during an engine shutdown when the feed pressure in the gallery 22 is discontinued, the terminus (plunger side port 26) of this passage means within the reservoir chamber is located at a point remotely distant axially of the lifter from the pressure chamber 11, and partition means having a one-way passage for flow of fluid into the reservoir chamber from said terminus is provided. -Inthe arrangement shown, this partition means and one-way passage is in the form of a generally cup-shaped element 27 having its open end abutting the end wall 10 of the plunger. The sides of this cup-shaped element 27 have a press fit against the inner side wall surfaces of the plunger 9, and adjacent the opposite .or closed end wall 28 of this partion element the side walls thereof are of reduced diameter as shownat 29 to allow flow of fluid into the plunger above the element 27. Press fitted into the larger open end section of this element is a seat piece 30 whose periphery is radially notched as shown at 37 in Figure 2 to accommodate fluid flow through the partition element. Centrally of the element end wall 28 is an aperture 32 which is normally closed by a check valve shown in the form of a ball 33. A coil compression spring 34 having one end resting on the seat piece 30 and its other end abutting the ball 33 serves to bias the ball to its closed position shown. This spring '34 must be selected to have a sufficiently low rate to not prevent the ball 33 from moving toward the seat piece 30 in response to fluid pressure entering the plunger via the port 26, yet must have sufficient force to effect seating of the ball 33 when the external fluid supply pressure is cut off during an engine shutdown.

Except for the action of the check valve 33 in preventing such reverse flow out of the reservoir chamber 12 the lifter operates in conventional manner. That is, during each lift stroke of the cam 4 the ball check valve 13 closes the passage 14 from the pressure chamber 11, trapping fluid in the latter, and this trapped fluid acts to transmit the cam thrust to the plunger 7 which acts through the push rod seat 16 and push rod 17 to operate the engine valve or other device to be operated. During each such lift stroke a certain amount of fluid from the pressure chamber 11 leaks between the side walls of the plunger and the cylinder bore 8 and is returned, for the most part, to the upper portion of the plunger via the grooves 21 and 25 and port 26. Such fluid as is lost, as by leakage between the upper end of the plunger (above the groove 21) and the cylinder bore 8, is replenished during engine operation via the gallery 22, cylinder groove 24 and cylinder port 23. When the engine is shut down it frequently happens that the lifter has not completed its full lift and return cycle, and hence has stopped in a fully or partially raised position. The opposing force applied to the push rod 17 by the engine valve return spring (not shown) causes the plunger 9 of the lifter to gradually leak down in the lifter cylinder 7, until the pressure chamber 11 is substantially run out of fluid through leakage between the plunger and the bore 8. Since this leakage fluid from the pressure chamber 11 and the fluid remaining in the upper end of the plunger (to the right of the partition element 27) may drain out of the lifter cylinder (via the cylinder port 23 or between the upper end of the plunger and the cylinder bore 8) during the period the engine remains shut down, suflicient fluid for replenishing the pressure chamber on restarting the engine would not be available were it not for the storage of fluid in the reservoir 12 by the partition element 27 and its check valve 33, and noisy operation of the lifter would result until suflicient fluid could be supplied via the ports 23, 26 and passage 14 to again fill the pressure chamber 11. In accordance with my invention, therefore, there is always an ample supply of fluid in the reservoir 12 even after a prolonged engine shutdown to immediately replenish the pressure chamber 11 of a fully leaked down lifter, and such noisy starts are accordingly avoided. Since the check valve 33 of my improved lifter will fully close the aperture 32 in the partition 27, the aforementioned result is attained with the lifter operated in a horizontal, or even in an inverted position (cam 4 above the lifter 1).

While only a single preferred embodiment of the invention has been disclosed, it is appreciated that numerous minor changes in the construction and arrangement of the parts may be made without departing from the spirit and scope of the invention as hereinafter claimed.

I claim:

1. In a hydraulic valve lifter, slidably interfitting cylinder and hollow plunger members defining a pressure chamber opposite one end of the plunger member and a reservoir chamber interiorly of the plunger member,

passage means interconnecting said chambers including means operative to restrict fluid flow from the pressure chamber to the reservoir chamber relative to flow in the opposite direction, other passage means extending into the plunger from the exterior of the lifter, said other passage means having its terminus within the reservoir chamber at a point remote from the pressure chamber, and a check valve within the reservoir chamber blocking drainage of fluid from the reservoir chamber via said other passage means.

2. In a hydraulic valve lifter, slidably interfitting cylinder and plunger members, the plunger member having side and end walls defining a reservoir chamber for fluid adjacent one end of the plunger member, registerable ports in the side walls of said members through which fluid may enter and leave the plunger member adjacent the opposite end of the plunger member, partition means within the plunger preventing drainage of fluid outwardly of said ports from said chamber, said partition means having a one-way passage therethrough for flow of fluid into said chamber.

3. In a dashpot device having a dashpot defining cylinder and a hollow plunger operable therein, means for supplying fluid to the dashpot including passage means extending into the plunger from the exterior of said.

device, said passage means having its terminus within the plunger at a point remote from the dashpot, and a check valve blocking reverse flow of fluid from within said plunger via said passage means.

4. In a dashpot device having a dashpot defining cylinder and a hollow plunger operable therein, means for supplying fluid to the dashpot including passage means extending into the plunger from the exterior of said device, said passage means having its terminus within the plunger at a point remote from the dashpot, and a check valve within the plunger at said terminus blocking reverse flow of fluid from within the plunger via said passage means.

5. In a hydraulic valve lifter adapted to be externally supplied with hydraulic operating fluid and to be operated in a generally horizontal thrust transmitting direction, generally cup-shaped cylinder and plunger members in slidably nested relation, the closed end of the cylinder member defining a pressure chamber for fluid to thrustably support the plunger member and the closed end of the plunger member having a check valve controlled aperture through which fluid may enter the pressure chamber from the interior of the plunger member, registerable side ports in the cylinder and plunger members through which externally supplied fluid may enter the plunger member, said ports being located remote from said plunger closed end, a partition defining a reservoir chamber in the plunger member between its said side No references cited.

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