US2619834A - Machine for testing hydraulic tappets - Google Patents

Description

Dec. 2, 1952 D. H. KELLY MACHINE FOR TESTING HYDRAULIC TAPPETS 5 Sheets-Sheet 1 Filed Aug. 4. 1948 1 e WNW W .nl z l/T W W Zlnuentor Dec. 2, 1952 D. H. KELLY MACHINE FOR TESTING HYDRAULIC TAPPETS 5 Sheets-Sheet 2 Filed Aug. 4, 194

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MACHINE FOR TESTING HYDRAULIC TAPPETS Filed Aug. 4, 1948 5 Sheets-Sheet 4 if 4/" GD Dec. 2, 1952 KELLY 2,619,834

MACHINE FOR TESTING HYDRAULIC TAPPETS Filed Aug. 4, 1948 5 Sheets-Sheet 5 t if if fl MICRO-SWIM g2 men/1922' maze-r l670 ISnventor pew/xii $71 441 Patented Dec. 2, 1952 UNITED STATES PATENT OFFICE MACHINE FOR TESTING HYDRAULIC vilAPPEtls Dennis 11, Kelly, Grand Rapids, Mich., assignor to General Motors Corporation, Detroit, Mich., a corporation of Delaware Application August 4, 1948, Serial No, Q2372 8 Claims. '1

This invention relates to a machine for testing hydraulic self-adjusting valve tappets and the like under simulated operating conditions. Hydraulic valve tappets for maintaining zero lash between the camshaft and valves of internal combustion engines have been used to a limited extent for many years. In their most common form they consist essentially of a vertical cupshaped cylinder closed at its upper end by a piston or plunger telescopically slidable and supported therein on a column of oil or other fluid confined in the bottom of the cylinder. The cylinder is slidably supported in the engine frame for longitudinally 'reciprocable movement in following one of the lobes on the camshaft, the piston moving therewith under the action of th oil column and effecting through" suitable linkage a corresponding movement of the engine valve which is biased to closed position by a relatively stiff spring. The piston is provided with a passage extending longitudinally therethrough which is closable by a check=valve sensitive to pressure within the chamber below the piston but which opens upon removal of that pressure to permit a flow of oil into the chamber from a reservoir above the piston, thereby tending to keep the pressure chamber filled at all times. A light spring is provided to bias the piston upwardly in the cylinder and thereby expand the tappet to tak up the valve lash during the interval between lifting strokes when the engine valve spring is unstressed. g

In order that hydraulic tappets of such general construction may perform properly to maintain zero lash in an engine valve linkage, two functions are essential. The first of these is referred to as leak-down and is the rate at which the tappet collapses under load due to leakage of oil by the piston from the pressure chamber into the reservoir. A certain minimum leak down is necessary to allow the tappet tocollapse asufficient amount to compensate for the thermal expansion of the other members of the valve linkage during engine warm-up and a maximum limit of leak-down is necessary to insure that th amount of oil displaced from the pressure chamber during one engine valve lifting stroke is not more than can be returned through the check-valve to the pressure chamber during the lull before the next stroke. The second necessary function is referred to as check-valve recovery, or ball recovery in tappets employing a b s d h c l e. and is repres ted by t dis nce hich t e tap t will co pse pon a su d n a plic tion of l ad ownwa y on the iston while the check-valve is closing fr m its fully op n position Wh le is a u must not exceed that which will insure sunicient engine valve opening and avoid excessive working of the tappet, it is also a measure of the capacity of the check-valve to pass oil from the reservoir to the pressure chamber and allow the tap pet to expand when the load thereon is removed, and hence has a minimum as well as a maximum desirable limit.

Heretofore, the ability of a tappet to function within desirable minimum and maximum limits as to leak-down and Check-valve recovery in an engine was ractically impossible to predict positively by dimensional inspections of the detail p s, and as a sult much ex e s n 'inconvenience has accompanied their incorporation in engines on a high speed production basis.

Accordingly it is the principal object of this invention to provide a machine for rapidly testing hydraulic tappets and the like for leak-down and check-valve recovery in order to anticipate their performance in actual us in an engine valve operating linkage.

Other obiects attained by the invention will be ap arent from a reading of the following despection, taken in connection with the drawings, in which:

Figure 1 is a general velevations view of a mach ne embodying the invention, and showing a valve tappet in position thereon for test.

Fi ure 2 is an e a d det l e i Pe pective showing the manner of supporting a valve tappet during its test and the cam and follower used in measuring checksvalve recovery.

Figure 3 is an enlarged sectional Vi w .of the machine taken substantially on 111616 3 .3 of Figure 1. certain parts being shown in elevation.

u e 4 is a nl d p an ew o the machine taken on line 4-4 of figure 1, with parts br k n way and in se ion Figure 5 is an enlarged detail view in perspec, tive showing the cam andone of the roller fol.- lowe s used in easurins taiin t l a'k d wn- F ure 6 is an, enla ed detail viewfin plan showi g 9 9i he weight lifting rocker arm assemblies, certain parts thereof being broken away and in section. H

Figure 7 is an enlarged detail view elevation showing portions of'some ofthe elements which makeup one :of 'the machin'es test st'ations and including further details on the means for supportin valve tai p t l -n' st. certain parts being broken away and shown in section.

Figure 8 is an enlarged detail plan view taken from lin 88 of Figure 3 and showing the arrangement of operating certain electrical switches for controlling the clocks used in measuring leak-down.

Figure 9 is an enlarged detail view in plan showing the mechanism employed for ejecting the valve tappets at completion of the test cycle.

Figure 10 is a circuit diagram of the leak-down timing control apparatus employed with each station.

Figure 11 is a diagram showing the timing of the different events during one revolution or cycle of a test station.

The machine as shown in the drawings comprises a rotatable carriage I resting on roller bearings 2 on a stationary supporting member or table 4 and journaled to a central column memher 8 extending vertically upward from the table 4. The column 8 is fixed at its lower end to the table 4 as by means of a key I8 and nut I2. The table 4 is encircled by a cylindrical guard I I fixed thereto and having a cut-out section M at the front of the machine, and rests on a hollow base I6 enclosing a driving motor I8. A stationary hood including a top 26 and cylindrical wall 22, also cut out at the front, and having circumferentially spaced window sections 84 serves to substantially enclose the moving parts of the machine.

The carriage is rotatably driven preferably at approximately I 7 R. P. M. from the motor I8 through pulleys 26, 28 and belt 36 by a pinion 32 meshing with an internal gear 34 fixedly secured to the underside of the carriage. Circumferentially spaced around the carriage I are a plurality (six, as shown) of tappet test stations, each including a supporting means for the cylinder 35 of a tappet 31 and comprising a platform member 36 disposed outwardly from the perimeter of the table 4 and rigidly suspended from the carriage I as by bolts 38 and 48. To provide a wear resistant bearing surface for the bottom of the tappet cylinder 35, an insert 39 of hard material such as a sintered metallic carbide is preferably provided flush with the top surface of the platform 36. Above the platform 35 and fixedly secured thereon by the bolts 38 and 48 is a U-shaped block 33, inwardly from the arms of which extend a pair of oppositely facing smaller blocks 4| and 42 fitted with spring biased buttons 43 adapted to resiliently engage opposite sides of the tappet cylinder 65. Suspended above the carriage I opposite each tappet support is a weight 44 (of the order of 50 lbs.) mounted on an arbor 45 slidable vertically in the carriage I. The lower end of the arbor 45 is provided with an adjustable extension 46 adapted to contact the upper end 41 of the tappet piston 48. The upper end of the arbor 45 is swingably connected to the outer end of a cam follower in the form of a rocker 49 which extends radially inward toward the spindle and which is pivoted intermediately of its ends on a bracket 50 secured to the carriage I. The inner end of the rocker 49 has a roller 5| journaled thereon opposite an annular center cam 52 provided with a single lobe 53 and fixedly secured to the column 8.

Mounted on the carriage I beneath each weight 44 are two micro-switches 54 and 55 having actuating buttons 56 and 51 respectively. Secured to the weight 44 opposite the buttons 56, 51 and adjustable in height for sequential contact therewith are two striker members 58 and 59. Micro-switch 55 is normally open and when actuated by the lowermost striker member 59 during downward movement of the weight 44 starts an electric clock 60 also carried by the carriage, while micro-switch 54 is normally closed and when actuated by the uppermost striker member 58 stops the clock 68. Also mounted on the carriage I, one above the other and opposite each weight 44 are a normally open microswitch 6| and a normally closed micro-switch 62, provided with actuating levers 63 and 64, respectively. Fixedly secured to the stationary column 8 are two trip dogs 65 and 66, one above the other and positioned in angularly staggered relationship for sequential operation of micro-switches 6| and 62, respectively. Micro-switch 6| when actuated by the trip dog 65 effects a resetting to zero position of the clock 66 of the test station with which it is associated, preparatory to that test station beginning each revolution with the carriage I. The micro-switch 62, is actuated by the trip dog 66 somewhat in advance of the actuation of micro-switch 6|, and serves to stop the clock 66 in the event a sluggish tappet in the test station prevents the weight 44 from actuating micro-switch 54.

Current leads 6'! and 68 for operating all of the clocks 65 are brought up through the passageway 69 and outlets l0 and II provided in the column 8 to stationary slip rings i2 and i3, trom which the current is delivered to brushes I4 and 15 mounted on an arm 16 anchored to one of the brackets 58 for rotation with the carriage The brushes l4 and T5 are connected through a suitable junction box (not shown) to each of the clock control circuits for the respective test stations. Figure 10 shows a representative diagram for one of the clock control circuits. The clock 86 operates only during energization of its time coil TI which in turn depends on the energization of the relay coil 18. In series with the relay coil 18 in a conductor line 19, 65, 8|, 82, 83 between the conductors 84 and 85 leading from the junction box are the two normally closed microswitches 54 and '62 and the normally open microswitch 55. Upon closing the micro-switch 55, The relay coil i8 is energized which causes the double-arm switch 86 to move from its normal position as shown to that in which its arm 8? connects the time coil 11 across the leads 84 and 85. At the same time, arm 88 of the switch 86 closes a holding circuit for the relay coil 18 through conductors 89 and 98. When either of the normally closed micro-switches 54 or 62 are opened the circuit through the relay coil 18 is broken, allowing the relay switch 86 to return to its normal position as shown which breaks the circuit through the time coil TI and stops the clock. In the normal position of the switch 86 the arm 83' connects one side of the reset coil 8| to conductor 85, and upon closing the normally open micro-switch 6| the other side of coil 8| is connected to conductor 84, which effects a resetting of the clock 68 to zero position.

Downward movement of each weight 44 is limited by its respective roller 5| returning to the base surface of the cam 52 after traveling off the single lobe 56 thereon. Directly under each weight 44 is a follower I68 slidable vertically in a bushing I I2 in the carriage and suspended therein by an enlargement H0 near its upper end. The upper end of the follower E68, above the enlargement H6, is provided with an adjustable extension I4 by means of which the necessary amount of clearance between the weight 44 (in its lowermost position) and the follower I88 may be set. Fixed tothe table 4 on the circular path described by the various followers I 08 in their rotation with the carriage I is a single lobe cam H5 having an inclined approach ramp H6 and a sharp'drop-off step III, separated by a flat dwell section H8. Secured for movement with the weight 44 is a dial indicator I I9 having a stem I registrable on the upper end of a screw I22, which is vertically adjustable in a bracket I24'bolted to the carriage I. By adjustment of the extension I I4 on the follower I08, the latter intraveling up the cam ramp H6 can be made to lift the weight M a sufiicient distance toallow the spring I 2i within the pressure chamber E23 of the tappet to force the piston 48 upward, relieving the fluid pressure therein and allowing the check-valve IZt to open and permit suflicient flow of fluid therethrough from the reservoir chamber I25 above the piston to equalize the pressures within the two chambers. Adjustability of the screw I22 is provided to obtain a zero reading of the indicator I I9 while the follower IIlii is at its maximum lift position, i. e. on the dwell section 8 E8 of the cam I I 5.

At the end of its test cycle (one revolution with the carriage I) each tappet is removed from its test station by the ejector lever I 28 associated therewith, in the manner illustrated in Figure 9. The ejector lever I28 is journaled at one end to the platform supporting bolt ti! and is biased out of contact with the tappet by the spring I34 to the position shown therein in fulllines. A trip dog I36 is fixedly secured to the table 3 in position to engage the end I 32 of the ejector lever I28. and rotate it about the bolt 46 to the position shown in broken lines, displacing the tappet,

In operation, with the carriage rotating continuously relative to the stationary table 4 and column 8, the operator inserts a tappet in each test station as the same is cleared by the lever I28 of the ejector mechanism. During the loading and unloading of a particular test station (see the test cycle timing diagram in Figure 11), the lobe 53 on the center cam 52 is in engagement with the roller M on the rocker 49 associated with that test station, holding the weight 44 in its uppermost position. As the carriage l continues to rotate the roller 5i travels 01f the lobe 53, allowing the weight M to fall and bring the arbor d5 therewith down upon the end l! of the tappet piston 58. As the tappet collapses under the load imposed by the weight 44, the latter moves downward with the tappet piston 68. As the tappet piston 48 moves down in its cylinder under the load imposed on it by the weight 4%, micro-switch 55 is actuated, starting the clock 69. The clock continues to run until the weight M has moved a further predetermined distance downward to actuate the micro-switch 5% which stops the clock. Under normal conditions, an ample period of time elapses-approximately 280 degrees of carriage rotationafter the center cam 52 releases the weight M (by the roller 5| associated therewith traveling off the lobe 53) for the weight to collapse the tappet sufficiently to come to rest at its lowermost position (roller 5! engaging the base surface of cam 52). From this position of rest the weight is subsequently lifted a predetermined amount and again dropped as the follower IE3 travels over the cam H5. The clock 53 and the indicator H9 associated with that particular test station, which has by this time returned to approximately the front of the machine, will now indicate the values for leakdown and check-valve recovery, respectively, for

the tappet being tested therein, and their readings may be noted by the operator. After a, brief interval, the micro-switch SI is actuated by moving into engagement with the tripdog 65 on the column 8, which resets the clock to zero position ready for the next cycle of that test station with another tappet, In the event a sluggish tappetone having an extremely slow leak-down rate-holds the weight M from moving down rapidly enough to actuate the micro-switch 55 and stop the clock within the period of the test cycle, the clock is stopped instead by the microswitch 62 engaging the trip dog 66, in advance of the resetting operation of micro-switch BI.

I claim:

1. A machine for testing leak-down and checkvalve recovery of hydraulic valve tappets, comprising a stationary supporting member, a column fixed thereto and projecting vertically upward from the center thereof, a carriage rotatably supported on the supporting member and journaled to the column, driving means for ef fecting continuous rotation of the carriage about the column, means carried by the carriage for supporting one end of a tappet in upright position thereon, weight means carried around the column by the carriage and gravitatively movable to effect axial collapsing of the tappet, a lever connected near one of its ends to the weight and fulcrumed intermediately of its ends on the carriage, a cam fixed to the column and operably engageable with the other end of the lever to effect a cyclic lifting, releasing and stopping of the weight relative to the tappet in timed relation with the rotation of the carriage, an electric clock carried by the carriage, clock start and stop switches carried by the carriage and operable successively by the gravitative movement of the weight following its release by the earn, an auxiliary clock stop switch and a clock reset switch carried by the carriage and operable successively by projections on the column as the carriage rotates relative thereto, a second cam fixed to the supporting member below the carriage, a follower carried by the carriage and engageable with the second cam to eifect a sequential lifting and free dropping of the weight as the carriage rotates further relative to the column after the gravitative movement of the weight has been stopped by the first mentioned cam, a dial indicator fixedly secured to the weight and having its operating stem registrable with the carriage for measuring the distance through which the weight drops immediately following its release by said follower, an ejector member carried by, the carriage for ejecting the tappet from its Supporting means on the carriage, a spring connected to the member for biasing the same to its inoperative position, and a cam fixed to the supporting member in position to effect a movement of the. ejector member in opposition to its spring to eject the tappet after the latter has substantially completed one revolution with the carriage about the column.

2. A machine for testing leak-down and checkvalve recovery of hydraulic tappets, comprising a continuously movable carriage for supporting the cylinder end of the tappet during test, weight means for applying a constant axial load on the piston end of the tappet in the direction tending to collapse the tappet, cam and lever means connected to said weight means and operable upon movement of the carriage to efiect axial loading and unloading of the tappet, time measuring means operable upon movement of the weight means for determining the time required for the tappet to collapse a predetermined amount under said load, a second cam and lever means operable upon movement of the carriage to effect a release and quick reapplication of said load after the operation of said time measuring means. and indicating means for measuring the amount which the tappet collapses immediately following the operation of said second cam and lever means.

3. A machine for testing hydraulic valve tappets for leak-down and check-valve recovery, comprising a support for one end of the tappet, means including a cam controlled weight engageable with the opposite end of the tappet and adapted to apply, a constant axial load tending to collapse the tappet during a limited period of time, a clock for measuring tappet leak-down and having starting and stopping means therefor operative upon movement of said weight between spaced positions, cam operated means operative after completion of said leak-down measurement to effect a relatively slow lifting and subsequent rapid dropping of the weight on the tappet, and. indicating means operative to measure the distance through which the weight moves during said rapid dropping thereof.

4. A machine for measuring the rate of flow of a fluid from a cylinder under the pressurizing action of a piston therein, comprising a stationary supporting member, a carriage resting thereon and rotatable about an axis perpendicular thereto, means on the carriage for releasably clamping a plurality of cylinder and piston assemblies to be tested at circumferentially spaced locations thereon, weights positioned on the carriage opposite each of said means and adapted to rest upon the pistons of the respective test assemblies, cam follower members connected to the respective weights, a cam fixed relative to the supporting member and having a cam track operably engageable with the followers to effect a lifting of each Weight from its respective piston during a portion of each revolution of the carriage, clock means for measuring the times required for the weights to force the pistons of the test assemblies a predetermined distance into their cylinders against the pressure of the fluid therein, and clock starting and stopping means operable by movement of the weights toward the carriage.

5. A machine for testing hydraulic tappets and the like for check-valve recovery, comprising a movable carriage provided with means for 8 application of said loading means by said cam means.

6. Apparatus for testing hydraulic tappets and the like for leak-down, comprising a continuously driven member for carrying the tappet cylinders in upright position during test, a weight carried by said member above each tappet, said weights having guided vertical movement relative to the member and adapted to be rested upon the tappet pistons, clock starting and stopping switches associated with each weight and mounted on the member, means on each weight for successively actuating said switches during downward movement of the weights, and a clock for measuring the time elapse between the actuations of said switches.

7. A machine for testing successive hydraulic valve tappets for rate of leak-down, comprising a support for one end of the tappet, a tappet loading weight slidably guided by the support and adapted when released to rest upon the opposite end of the tappet, a cam for eifecting alternate raising and releasing of the weight, said cam being movable relative to the support having cam following means movable with the weight, means for effecting continuous relative movement between the cam and the support to efiect a periodic weight lifting movement of said following means, and a clock having starting and stopping means actuated by the weight for measuring the time required for the tappet to leak down a predetermined extent while supporting the weight.

8. A machine for testing hydraulic valve tappets for rate of leak-down, comprising a stationary supporting member, a carriage rotatably mounted on the supporting member, driving means for rotating the carriage, supporting means for one end of the tappet carried by the carriage. a tappet loading member carried by the carriage and movable relative thereto against the opposite end of the tappet, a cam on the supporting member operative during rotation of the carriage to effect the withdrawal of the loading member from the tappet following completion of the leak-down test, and time measuring means including a clock having carriage mounted starting and stopping devices actuatable by the loading member as the loading member moves relative to the carriage in response to tappet leak-down.

DENNIS I-l'. KELLY.

REFERENCES CITED following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,225,438 Howard May 8, 1917 1,962,174 Christman June 12, 1934 2,045,548 Dillon et al. June 23, 1936 2,263,801 Graham Nov. 25, 1941 2,334,970 Voorhies Nov. 23, 1943

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