US3299870A - Valve-operating mechanism for internal combustion engines - Google Patents

Description

Jan., 24, w67 R. BERTSCH ETAL 3,299,870

VALVE-OPERATING MECHANISM FOR INTERNAL COMBUSTION ENGINES Filed Jan. 2l, 1966 2 Sheets-Sheet l Q5 we w* .n is

J., 24, 1967 R. BERTscH ETAL 3,299,870

VALVE-OPERATING MECHANISM FOR INTERNAL COMBUSTION ENGINES Filed Jan. 2l, 1966 2 Sheets-Sheet 2 "3% i HI u i Y 'lg-f5 United States Patent O 3,299,870 VALVE-OPERATENQ MECHANESM FOR HNTERNAL COMBUSTEON ENGENES Richard Bertsch, Asperg, and Josef Heinzelmann, Ab-

iach, near Sigmaringen, Germany, assignors to Robert Bosch G.m.b.H., Stuttgart, Germany Filed Jan. 21, 1966, Ser. No. 522,2l7 Claims priority, application Germany, Feb. 6, 1965, B 80,405 9 Claims. (Cl. 12d-90) The present invention relates to valve-operating mechanisms for internal combustion engines, and particularly to improvements in hydraulic valve tappet mechanisms. Still more particularly, the invention relates to improvements in hydraulic valve tappet mechanisms of the type which are provided with automatic valve clearance eliminators, also called lash eliminators.

lt is already known to provide a valve tappet mechanism with a valve which permits outflow of some oil from the chamber of the lash eliminating unit and to use such oil to lubricate certain relatively movable parts of the valve-operating mechanism in which the tappet is put to use. The valve acts not unlike a throttle and cannot completely prevent escape of oil from gthe chamber. The chamber of the lash eliminating unit normally receives oil through a large number of inlets whereby the oil escapes when the engine is idle so that the chamber is lled with air. The escaping oil can contaminate the interior of the engine. Also, it 4takes about 15 minutes to rell the chamber with oil when the engine is restarted whereby the mechanism rattles and produces what is known as tappet noise. Furthermore, and since oil which is used to lubricate the moving parts of the valve-operating mechanism is not supplied in metered quantities, it happens again an-d again that the parts which require lubrication receive too much oil or too little oil. Both such extremes are undesirable, particularly excessive lubrication because surplus oil is supplied at the expense of other lubricant consuming stations. Freely floating lubricant admitting valves are likely to jam and to either prevent satisfactory lubrication or to permit excessive lubrication each of which may cause serious damage to the engine. Proposals to admit lubricant through a hollow push rod and toward the tappet also have met with little success because the rocker arm at the remote end of the push rod is disstant from the customary oil circulating system of the engine so that the introduction of oil into the remote end of the push rod necessitates the provision of special conduits with attendant increase in cost and other inconveniences. In a manner well known from the art of valveoperating mechanisms for internal com-bustion engines, the push rod has one of its ends journalled in a cup of the tappet and its other end transmits motion to a rocker arm which, in turn, effects seating and unseating of an exhaust valve or another valve which regulates the flow of uids to or from the cylinder of an engine.

It is now an important object of the present linvention to provide an improved valve-operating mechanism for internal combustion engines wherein the tappet is constructed and assembled in such a way that the chamber of the lash eliminating unit cannot receive air and wherein the tappet simultaneously insures proper and fully controlled lubrication of the push rod and, if necessary, of certain other movable parts in the engine.

Another object of the invention is to provide a mecha- 3,299,870 Patented Jan. 24, 1967 ICC nism of the just outlined characteristics which can be readily connecte-d in the oil circulating system of a conventional internal combustion engine and wherein such connection necessitates the provision of very short oil conveying passages.

A further object of the invention is to provide a hydraulic valve tappet which can control the admission of lubricant to the push rod with utmost accuracy, in automatic response to starting of the engine, and at a rate which remains constant for any desired length of time and at different temperatures.

An additional objects of our `invention is to provide a tappet whose operation is noiseless, wherein such noiseless operation is insured at all times whenever the engine is in operation and immediately after the engine is started, and which consists of a small number of relatively simple and compact parts.

Still another object of the invention is to provide a hydraulic valve tappet wherein the chamber of the lash eliminating unit is invariably and fully sealed from the system which admits metered quantities of lubricant to the cup or cups for the push rod and wherein the chamber is not likely to receive air when the valve-operating mechanism is in working condition.

A concomitant object of the invention is to provide a hydraulic valve tappet which can be readily substituted for the tappets of presently known valve-operating mechanisms for use in internal combustion engines.

Briey stated, one feature of our present invention resides in the provision of a valve-actuating mechanism, particularly for use in internal combustion engines. The mechanism comprises a driven cam which rotates about a fixed axis, a housing adjacent to the cam and having a guide bore therein and an oil supply channel which is permanently filled with lubricant and communicates with the guide bore, a hydraulic valve tappet including a hollow cupped body reciprocably received in the guide bore of the housing and having an end Wall in motion-receiving engagement with the cam, a lash-eliminating plunger reciprocably received in the body Iand defining with the end wall a compensating chamber, a second chamber provided in the plunger and communicating with the cornpensating chamber, a cup rigid or integral with the plunger and defining a `socket which faces away from the end wall of the body, and one-way valve means provided 'between the two chambers for admitting oil from the second chamber to the compensating chamber, and a push rod having an end portion extending int-o the socket and arranged to bias the plunger in a direction toward the end wall and to thereby maintain the end wall in permanent motion-receiving engagement with the cam. The body and the plunger of the valve tappet dene a first passage which establishes a permanent connection between the oil supply channel and the second chamber and a second passage for admitting oil from the channel to the socket. The rst passage includes a single inlet to the second chamber and the second passage is preferably` municates with its socket (and hence with the axial bore of the push rod) and serves to admit oil to the periphery of the shaft so that the latter is properly lubricated in response to reciprocation of the valve tappet body.

The novel features which are considered as characteristic of the invention are set forth in particular in the appended claims. The improved valve-operating mechanism itself, however, both as to its construction and its mode of operation, together with additional features and advantages thereof, will be best understood upon perusal of the following detailed description of a specific embodiment with reference to the accompanying drawings, in which:

FIG. 1 is a fragmentary section through an internal combustion engine and illustrates a portion of a valveactuating mechanism which embodies our invention;

FIG. 2 is a section as seen in the direction of arrows from the line II--II of FIG. 1 and shows two adjoining tappets; and

FIG. 3 is an enlarged axial sectional View of the tappet which is shown in FIG. 1.

Referring rst to FIG. l, there is shown a portion of an internal combustion engine embodying a valve-operating mechanism which includes the improved hydraulic valve tappet 2. This tappet comprises a cupped cylindrical b-ody 27 which is reciprocable in a guide bore 18 machined into the housing 1 of the internal combustion engine. The end wall 28 of the body 27 abuts against and receives motion from a cam 3 which is mounted on a driven cam shaft 4. A cup 36 of the tappet 2 defines a socket or seat 48 (see FIG. 3) which receives one end portion 14 of an elongated hollow push rod 5. The other end portion 13 of the push rod 5 is free to swivel in a socket 12 provided at one end of a leg 6 forming part of a rocker-arm 7 which is rockable on a rocker arm shaft 7a. The other leg` 8 of the rocker arm 7 carries an adjustable motion transmitting `screw 8a which abuts against the stem 9aof a valve member 9 forming part, for example, of an exhaust valve for the cylinder of the internal combustion engine. The screw 8a actually bears against a follower 9b which constitutes a retainer for one end of a helical valve spring 9'. The other end of the spring 9' bears against a stationary part 1a of the housing 1'so that this spring normally tends to maintain the valve member 9 in sealing engagement with its seat 1b. At the same time, the spring 9' biases the push rod I ina direction to the left, as viewed in FIG. 1, whereby the end wall 28 of the valve tappet body 27 bears against the face of the cam.3. The leg 6 of the rocker arm 7 is formed with a b-ore 11 which communicates with the axial bore 15 of the push rod 5 viasocket 12 and conveys lubricant to the bore of the rocker arm, i.e., to the periphery of the rocker arm shaft 7a. The end portions 13, 14 of the push rod 5 are of substantially semispherical shape and the ends of the bore 15 in the push rod 5 are conhgurated in such a way that this bore is in permanent communication with the `bore 11 as well as with a bore 49 (see FIG. 3) which forms part of a passage for conveying lubricant to the socket 48 of the cup 36.

The oil is supplied by an oil supply channel 16 which is machined into the housing 1 and which is connected to the oil circulating system of the engine. FIG. 1 shows that the channel 16 communicates with the guide bore 13, and FIG. 2 shows that this channel 16 can supply oil to a plurality of tappets including the tappet 2 and a second tappet 2', the latter being reciprocable in a second guide bore 17 of the housing 1 and receiving moti-on from a second cam 3' on the cam shaft 4. The tappet 2 transmits motion to a second push rod 5', and is external surface 19 is formed with two adjacent butV spaced circumferential grooves 21, 22 respectively communicating with radially inwardly extending bores 25', 26'. Since the construction of the tappets 2, 2' is identical, FIG. 3 merely shows the details of construction of the tappet 2. The soledierence between the two tappets is that they move with reference to each other because the angular position of the cam 3' is different from that of the cam 3. The external surface 20 of the tappet 2 (i.e., of its body 27) is formed with two circumferential grooves 23, 24 which respectively corresponds to grooves 21, 22, and with two radial bores 25, 26 which respectively correspond to the bores 25', 26'. The oil supply channel 16 is substantially normal to the guide bores 17, 18 and is in permanent communication with the groove 23 (and also with the groove 21). The cylindrical portion -or skirt of the body 27 shown in FIG. 3 accommodates a reciprocable plunger 29 which is rigid with the cup 36 whereby the socket 48 of the cup 36 faces away from the end wall 28 of the body. The spring 9 shown in FIG. 1 biases the plunger 29 in a direction to the left, as viewed in FIG. 3. The left-hand end face 30 of the plunger 29 defines with the bottom wall 28 a compensating chamber 31 which forms part of the lash eliminating unit and is always lled with oil. This chamber 31 communicates with a second chamber 38 which is formed in the plunger 29 and one end of which is sealed by the cup 36.

The plunger 29 is sealingly telescoped into the bore 33 of the body 27, and its external surface 32 is formed with two peripheral grooves 34, 35 which respectively communicate with the bores 25, 26. The grooves 34, 35 are outwardly adjacent to the cup 36 which abuts against an internal shoulder 37 of the plunger 29. The periphery of the cup 36 is provided with two grooves 45a, 46a which respectively communicate with the grooves 34, 35 through the intermediary of radial bores 45, 46 provided in the plunger 29. The cup 36, which can be considered as constituting a component or integral part of the plunger 29, is formed with an inclined bore 47 which connects the groove 45a with the second chamber 38, and with the radially extending bore 49 which connects the groove 46a with the socket 48. The groove 34, the bore 45, the groove 45a and the bore 47 together constitute a single inlet to the second chamber 38, and this inlet forms part of a first passage which further includes the groove 23 4and the bore 2S and serves to permanently connect the oil supply channel 16 with the chamber 38. The second passage includes the groove 24, the bore 26, the groove 35, the bore 46, the groove 46a and the bore 49, and the function of this second passage is to intermittently connect the oil supply channel 16 with the socket 48 and hence with the axial bore 15 of the push rod 5.

A one-Way ball valve 39 controls the how of oil between the chambers 31 and 38 in such a way that oil can ilow from the chamber 38, through a connecting bore 40 in the left-hand end portion of the plunger 29,v and into the chamber 31 but not in the opposite direction. The valve 39 comprises a spherical valve member 42 which is biased against its seat the left-hand end of the bore 40 by a valve spring 41 mounted in a cage 43 which is biased against the plunger 29 by a strong helical expansion spring 44. The spring 44 is accommodated in the compensating chamber 31 and -operates between the end lwall 28 and an outwardly extending ange of the cage 43.

The internal surface surrounding `a counterbore 50 at the right-hand axial end of the body 27 is formed with an annular groove for a retaining ring 51 which acts not unlike a stop and serves to prevent the plunger 29 from moving too far away from the end wall 28. The end portion 14 of the push rod 5 extends through the counterbore 5t) and is free to swivel in the socket 48 of the cup 36. The ring 51 lalso prevents the plunger 29 from falling out during assembly of the tappet 2.

The valve-operating mechanism of our invention operates as follows:

When the engine is running, the supply channel 16 is filled with oil which is maintained under pressure by the lubricating pump, not shown. The axial length of the groove 23 in the peripheral surface 26 of the-tappet body 27 is selected in such a way that the bore 25 is in permanent communication with the channel 16. The same holds true for the groove 34 and bore 45 so that the chamber 38 is permanently filled with oil entering through the inlets 34, 45, 45a, 47. The engine drives the cam shaft 4 so that the cam 3 rotates and cooperates with the valve spring 9 to reciprocate the tappet 2 whereby the latter causes the valve member 9 to move away from its seat 9b when the push rod 5 moves in a direction to the right, as viewed in the drawings. As stated before, the axial length of the lgroove 23 is such that the bore 25 remains in permanent communication with the channel 16 despite the fact that the tappet 2 reciprocates in the guide bore 18 of the housing 1. Whenever necessary, the one-way valve 39 admits oil from the chamber 38 into the chamber 31 to make sure that the tappet will operate without lash. The valve 39 admits oil to the chamber 31 when the plunger 29 moves away from the end wall 28 of the body 27. The axial length of grooves 34, 35 in the peripheral surface 32 of the plunger 29 is such that these grooves remain in communication with the bores 25, 26 even if the plunger changes its axial position with reference to the body 27. As a rule, the plunger 29 will be free to perform strokes of up to 4 mm. so that the effective length of the tappet 2 (between the outer side of the end wall 28 and the bottom zone of the socket 4S) may be varied by the same distance.

While the channel 16 remains in permanent communication with the chamber 38 in the plunger 29, the socket 48 receives oil intermittently in response to rotation of the cam 3 and in response to resulting reciprocation of the tappet 2. In FIG. 3, the groove 24 is shown in an `axial position in which it cannot communicate with the channel 16. However, when the tappet 2 is shifted by the lobe of the cam 3 to assume an axial position corresponding, for example, to that of the tappet 2 shown in FIG. 2, the groove 24 will communicate with the channel 16 and will admit oil to the bore 49 and socket 48. The bore 49 may receive oil during about one-seventh (about 50) of each full revolution of the cam 3. The amounts of oil which are admitted to the socket 48 are accurately metered and the metering of oil is not affected by changes in temperature. The second passage including the groove 24 and bore 49 throttles the flow of oil to the socket 48, and the rate at which the socket 48 receives oil is properly related to the rotational speed of the cam shaft 4.

The oil which is discharged from the bore 49 lubricates the end portion 14 of the pushrod 5 and also fiows through the axial bore to lubricate the socket 12. Some such oil ows further through the bore 11 of the leg 6 and lubricates the surface surrounding the bore 10 of the rocker arm 7 as well as the periphery of the rocker arm shaft 7a. If desired, the leg 8 of the rocker arm 7 may also be provided with a bore (indicated at 11a) which can convey lubricant all the way to the valve spring 9.

A very important advantage of the improved tappet is that the chamber 38 of the plunger 29 is sealed against entry of air, even when the engine is idle for extended periods of time. This is due to the fact that the chamber 38 is provided with a single inlet including the inclined bore 47, and also :because the chamber 38 is invariably sealed from the socket 48. The two passages which respectively convey lubricant to the chamber 38 and socket 48 are very short so that proper lubrication of the push rod 5 and proper operation of the lash eliminating unit can begin in immediate response to starting of the engine.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features which fairly constitute essential characteristics of the generic and specific aspects of our contribution to the art and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be protected by Letters Patent is: i

1. In a valve-operating mechanism for internal combustion engines, a driven cam; a housing adjacent to said cam and having a guide bore therein and an oil supply channel communicating with said bore; a valve tappet including a hollow body reciprocably received in said bore and having an end wall in motion-receiving engagement with said cam, a lash-eliminating plunger reciprocably received in said body and defining with said end wall a compensating chamber, said plunger further having a second chamber communicating with said compensating chamber and a cup defining a socket facing away from said end wall, and one-way valve means provided between said chambers for admitting oil to said compensating chamber; and a push rod having an end portion extending into said socket and arranged to bias said plunger in a direction toward said end wall, said body and said plunger defining a first passage permanently connecting said channel with said second chamber and a second passage for admitting oil from said channel to said socket, said second passage being in permanent communication with said socket and in intermittent communication with said channel in response to reciprocation of said body.

2. A structure as set forth in claim 1, wherein said first passage includes a single inlet to said second chamber.

3. A structure as set forth in claim 2, wherein said second chamber is adjacent to said cup and is permanently sealed from said socket, said inlet including a single bore extending from said second chamber toward the periphery of said plunger.

4. A structure as set forth in claim 3, wherein said first passage further includes a bore provided in said body and connecting said inlet with said channel.

5. A structure as set forth in claim 4, wherein said first passage further includes a circumferential groove provided in said plunger and connecting said inlet with the bore of said body in each axial position of said plunger with reference to said body.

6. A structure as set forth in claim 1, wherein said second passage includes a peripheral groove provided on said body and movable into and from registry with said channel in response to reciprocation of said body, a bore provided in said body in permanent communication with said groove, a second peripheral groove provided on said plunger in permanent communication with said bore, and a further bore provided in said plunger to connect said second peripheral groove with said socket.

7. A structure as set forth in claim 1, wherein said push rod has an axial bore communicating with said second passage and comprises a second en-d portion distant from said tappet, and further comprising a shaft and a rocker arrn mounted on said shaft, said rocker arm defining a socket for the second end portion of said push rod and having a bore connecting the bore of said push rod with the periphery of said shaft so that the shaft is lubricated in response to admission of oil from said channel to said second passage.

8. A structure as set forth in claim 1, wherein each of said passages comprises a circumferential groove provided on said body, a peripheral groove provided on said plunger, and a radial bore connecting the circumferential groove with the peripheral groove, said inlet being in permanent communication with the peripheral groove of said first passage and the circumferential groove of said first passage being in permanent communication with said channel, the circumferential groove of said second passage being movable into and out of registry with said channel in response to reciprocation of said body and said second passage further including bores provided in said plunger and in said cup to establish a permanent communication between said socket and the 7 '8 peripheral groove of said second passage, said second 2,821,970 2/ 1958 Line 123-90 chamber being permanently sealed from said socket. 2,874,685 2/ 1959 Line 12S-90 9. A structure as set forth in claim 1, wherein said 2,938,508 5/ 1960 Papenguth 123-90 cam is rotatable about a xed axis and further compris- 3,070,080 12/1962 Van Slooten y123-90 ing stop means for determining the maximum stroke of 5 3,111,119 11/ 1963 Bergmann 123-90 said plunger in a direction away from said end Wall. 3,177,857 4/1965 Kuchen et al. 12.3-90

References Cited by the Examiner MARK NEWMAN, Primary Examiner.

UNITED STATES PATENTS AL LAWRENCE SMITH, Examiner.

2,259,905 10/1944 Moncrieff 12s-9o 10

Claims (1)

1. IN A VALVE-OPERATING MECHANISM FOR INTERNAL COMBUSTION ENGINES, A DRIVEN CAM; A HOUSING ADJACENT TO SAID CAM AND HAVING A GUIDE BORE THEREIN AND AN OIL SUPPLY CHANNEL COMMUNICATING WITH SAID BORE; A VALVE TAPPET INCLUDING A HOLLOW BODY RECIPROCABLY RECEIVED IN SAID BORE AND HAVING AN END WALL IN MOTION-RECEIVING ENGAGEMENT WITH SAID CAM, A LASH-ELIMINATING PLUNGER RECIPROCABLY RECEIVED IN SAID BODY AND DEFINING WITH SAID END WALL A COMPENSATING CHAMBER, SAID PLUNGER FURTHER HAVING A SECOND CHAMBER COMMUNICATING WITH SAID COMPENSATING CHAMBER AND A CUP DEFINING A SOCKET FACING AWAY FROM SAID END WALL, AND ONE-WAY VALVE MEANS PROVIDED BETWEEN SAID CHAMBERS FOR ADMITTING OIL TO SAID COMPENSATING CHAMBER; AND A PUSH ROD HAVING AN END PORTION EXTENDING INTO SAID SOCKET AND ARRANGED TO BIAS SAID PLUNGER IN A DIRECTION TOWARD SAID END WALL, SAID BODY AND SAID PLUNGER DEFINING A FIRST PASSAGE PERMANENTLY CONNECTING SAID CHANNEL WITH SAID SECOND CHAMBER AND A SECOND PASSAGE FOR ADMITTING OIL FROM SAID CHANNEL TO SAID SOCKET, SAID SECOND PASSAGE BEING IN PERMANENT COMMUNICATION WITH SAID SOCKET AND IN INTERMITTENT COMMUNICATION WITH SAID CHANNEL IN RESPONSE TO RECIPROCATION OF SAID BODY.

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