US 3332405 A
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July 25, 1967 3 s. HAVILAND I 3,332,405
INTERNAL COMBUSTION ENGINE BRAKE Filed Oct. 1, 1965 3 Sheets-Sheet l y 25, 1967 G. s. HAVILAND INTERNAL COMBUSTION ENGINE BRAKE 3 Sheets-Sheet y 1967 G. s. HAVILAND 3,332,405
INTERNAL COMBUSTION ENGINE BRAKE Filed. Oct. 1, 1965 3 Sheets-Sheet 3 F/GB United States Patent I 3,332,405 INTERNAL COMBUSTION ENGINE BRAKE Girard S. Haviland, West Hartford, Conn., assignor to The Jacobs Manufacturing Company, West Hartford, Conn., a corporation of New Jersey Filed Oct. 1, 1965, Ser. No. 491,977 9 Claims. (Cl. 12397) This invention is concerned with mechanism for braking or retarding the speed of an internal combustion engine by opening an exhaust valve of a piston cylinder at or near the end of a compression stroke so as to relieve the cylinder of compressed gas and, as a consequence, of the power which would otherwise be applied to the piston.
The general object of this invention is to provide improved control mechanism for this purpose, which is economical to manufacture because of its limited number of parts; which occupies very limited space so as to be practical for incorporation in an engine; and which is efiicient in its operation and reliable for the purposes intended because of its extremely fast on-and-oif action.
The invention is especially suited for use in motor vehicles as a means auxiliary to customary braking mechanism for retarding the speed of the vehicle when needed. Such need is particularly demanded by heavy hauling vehicles to share the burden of customary brakes. This need may arise when the vehicle is descending a long steep grade, in cases of brake failure, and in other situations.
In the accompanying drawings:
FIG. 1 is a schematic view showing a rocker arm associated with the exhaust valves of one cylinder of a bank of several cylinders of an internal combustion engine of the fuel injector or diesel type, served by an overhead camshaft which is cooperable with the rocker arm to open at the normal time the exhaust valves of the cylinder, and with which the present invention is associated for selectively causing the exhaust valves to open at or near the end of a compression stroke of the piston;
FIG. 2 is a section taken on line 22 of FIG. 1, but showing the location of the rocker arm shaft as it appears in the physical structure;
FIG. 3 is a detail showing the position of the auxiliary cam relative to the latch piston spring;
FIGS. 4 and 5 correspond respectively to FIGS. 1 and 2 in operative condition;
FIG. 6 is a view similar to FIG. 2 but showing a modification in the means for limiting the extent of movement of the latch piston;
FIG. 7 is a section on line 7-7 of FIG 6;
FIG. 8 schematically shows the invention in modified form as applied to a cylinder of an internal combustion engine of the non-overhead camshaft type; and
FIG. 9 is a section taken on line 99 of FIG. 8.
In FIGS. l-5, the invention is shown as applied in an internal combustion engine of the fuel injector or diesel type to one cylinder 10 of a bank of piston cylinders. The piston may be of the four-stroke or two-stroke cycle type. The usual fuel injector and air intake mechanism associated with the cylinder 10 are not shown since only so much of the engine as is required for an understanding of the invention is illustrated. The cylinder 10 is served by a pair of exhaust valves 11 normally held in closed condition by the usual spring means 12. Both valves are actuable to open condition by means of a common rocker arm 13 pivoted upon a rocker arm shaft 14. The rocker arm is actuable by means of an overhead exhaust camshaft 15, shown in broken line, to open the exhaust valves at the normal or usual time in the cycle of the related piston 16, and also at or near the end of the compression stroke of the piston. The camshaft is oper- Patented July 25, 1967 able in conventional manner by means of a crankshaft (not shown). The camshaft carries a regular cam 17 (broken line) which is cooperable at the normal time in a piston cycle with a roller 18 mounted in the rocker arm to pivot the latter to open the exhaust valves. The camshaft also carries an auxiliary cam 19, (broken line) which is cooperable with a latch piston 21 in the rocker arm to cause pivoting of the rocker arm to open the exhaust valves at or near the end of a compression stroke, the timing of the opening of such valves being determined by the angular position of the cam upon the cam haft.
The latch piston is selectively controlled so as to be cooperable with the auxiliary cam only when the occasion demands. The latch piston is disposed in a socket or bore 22 formed below the auxiliary cam in the upper surface of the rocker arm. The latch piston is hydraulically movable upwardly for a limited distance above the surface of the rocker arm to a position as in FIG. 5 wherein its projecting surface is engageable by the auxiliary cam 19 as the camshaft rotates. A stop piece 23 anchored by screw means 24 t9 the surface of the rocker arm has a lip portion 25 which overhangs the bore 22 and cooperates with the latch piston to limit the extent of upward movement of the latter. A spring 26 anchored to the stop piece has a pair of bifurcated arms 27 overhanging and constantly pressing downwardly upon the upper surface of the latch piston. The arms of the spring serve to hasten return of the latch piston to normal position out of the path of rotation of the auxiliary cam when hydraulic pressure beneath the latch piston is relaxed. The auxiliary cam 19, as appears in FIG. 3, is disposed for rotation by the camshaft in the bifurcation 28 between the arms of the spring so as to engage the latch piston in the raised position of the latter.
The means controlling movement of the latch piston includes a solenoid valve unit 29 selectively operable by the operator. A manual switch means (not shown) on the instrument panel or a switch associated with the foot brake or other suitable means may be employed for this selective operation. The solenoid valve has a normal deenergized condition, as in FIG. 1, wherein an intake or supply passage 31 connected through a pump 32 to the engine oil sump (not shown) is blocked from communication with the bore of the latch piston. When the solenoid valve is in its energized or operated condition, as in FIG. 4, it seals off a relief passage 33 connected to the oil sump and communicate the intake passage 31 with an outlet passage 34, whereby pressurized hydraulic fluid flows from the sump through the outlet passage into a chamber 35 defined by the interior of the rocker arm shaft. It then flows from this chamber through a port 36 into a chamber 37 of a control valve unit, generally indicated at 38. Thecontrol valve unit includes a clapper valve seat 39 resting upon an annular shoulder at the bottom of a counterbore 42 formed in a side of the rocker arm. A plug 43 screwed into the counterbore has a short end skirt abutting the clapper valve seat 39. This construction provides a narrow space interiorly of the skirt above the clapper valve seat, in which space a clapper or disc valve 45 is movable relative to a central opening of the seat 39. The clapper valve is normally held in open condition, as in FIG. 1, by means of a dump finger 46, whereby the valve chamber 37 is connected through the open clapper valve 45 with radial ports communicating with a passage 47 in the rocker arm. Passage 47 is connected with the bottom end of the latch piston bore. The dump finger extends with clearance at 48 through a head end of a dump piston 49; and the dump finger has a head 51 resting within the interior of the dump piston upon a spring 52. This spring presses the head of the dump finger relative to the dump piston so that a seat 53 about the base of the dump finger normally seals the clearance 48. The bias of spring 52 normally holds the dump piston and the dump finger raised so that the dump finger holds the clapper valve 45 clear of its seat, as in FIG. 1. A light spring 50 keeps clapper valve 45 urged toward seat 39.
In the operation of the arrangement described, energization of the solenoid valve unit 29 permits sump oil to be pumped through the solenoid valve to the interior chamber 35 of the rocker arm, and from the latter through port 36 to the control valve unit chamber 37. The sump oil, which is under a constant pump pressure of 50 p.s.i., acts over the head end of the dump piston 49 and forces the latter downwardly with the dump finger as a unit against the resistance of spring 52, allowing the clapper valve 45 to drop upon its seat. Upon this action, the pressurized sump oil forces its way past the clapper valve into passage 47 leading to the underside of the latch piston, causing the latter to project out of the rocker arm against the resistance of spring 26 until it is limited by the stop 25 against further outward movement, as in FIG. 5. The clapper valve, when unsupported by the dump finger acts in the manner of a check valve allowing flow of sump oil to the bore 22 of the latch piston but blocking return therefrom, whereby the latch piston becomes hydraulically locked in its moved position as long as the solenoid valve unit is held in its energized condition. While the latch piston is so locked, rotation of the camshaft brings the auxiliary cam 19 into camming engagement with the projecting latch piston at or about the end of the compression stroke of the engine piston 16. This causes the rocker arm to pivot downwardly and open the exhaust valves of the piston cylinder, allowing compressed gas in the piston cylinder to vent to atmosphere. The valve return springs 12 next function to reclose the exhaust valves following blow-down during the stroke succeeding the compression stroke. As long as the solenoid valve is held energized this camming action of the auxiliary cam is repeated as the camshaft rotates. The regular cam 17 continues as usual, despite the projected condition of the latch piston, to pivot the rocker arm to open the exhaust valves.
When the solenoid valve 29 is de-energized, it returns to normal position, as in FIG. 1. The supply or intake pasage 31 is then again blocked from the outlet passage 34, and the outlet passage is placed in communication through the solenoid valve with the relief passage 33. The latter passage is controlled by a relief valve 54 which allows pressurized fluid in the outlet passage 34 to flow to sump thereby relaxing the pressure of the fluid in the dump finger chamber 37. As this occurs, the dump piston is returned by its spring 52 upwardly with the dump finger to reopen the clapper valve. As the hydraulic fluid below the latch piston is then relieved through the connected passages, the open clapper valve 45 and the relief valve 54 to sump, the auxiliary cam 19 upon again contacting the latch piston returns it to normal condition in its bore, unless the depressing action of the return spring 26 has already done so. When the hydraulic pressure in the solenoid valve drops to 2 p.s.i. as the hydraulic fluid flows through the relief valve 54 to sump, the latter valve is adapted to close, whereby the passages connecting the solenoid valve with passage 47 leading to the latch piston bore remain filled with the residual hydraulic fluid at a pressure of 2 p.s.i. The latch piston, however, remains seated in disabled condition at the bottom of its bore, since this 2 p.s.i. pressure of residual fluid in the associated passages is not enough to move it out of its bore against the resistance of the latch spring 26.
If, during the time the solenoid valve is energized, the pressure in chamber 37 of the control valve unit should for some reason exceed 50 p.s.i., the excess pressure will act through the clearance 48 upon the head 51 of the dump finger to depress the latter against the spring 52 so as to unseal the clearance 48, whereupon the excessive pressure will be relieved by fluid flow around the head of the dump finger and through the open bottom end of the dump piston to a relief port 55 connected to sump.
A hydraulic lube line 56 independent of the solenoid valve unit and carrying oil at less than 2 p.s.i. has a connection with the rocker arm for purposes of lubricat ing the rocker arm relative to the rocker arm shaft through fine orifices (not shown). This fluid also serves to maintain the hydraulic passages between the solenoid valve and the piston bore filled during the time the latch piston and solenoid valve are de-activated. An advantage of this arrangement is that the filled passages allow the latch piston to respond immediately to energization of the solenoid valve and move to its active position. An advantage of the reilef valve 54 is that it permits immediate relaxation of pressure in chamber 37 and below the latch piston, thus allowing fast de-activation of the latter.
FIGS. 6 and 7 show a variation in the means for limiting the extent of movement of the latch piston relative to the rocker arm. Here, the latch piston 21a is formed with a transverse hole 76. A stop pin 77 of smaller diameter than the hole 76 is fixed in the rocker arm 13 and extends through the hole. The upper wall area of the hole abuts under the tension of a return spring 78 upon the stop pin in the normal disabled position of the latch piston. The spring is confined in a bore 79 directly below the stop pin, and it limits at its bottom upon a plug 81 Bore 79 is a smaller diameter than the stop pin; and When the latch piston its hydraulically actuated, the lower Wall area of hole 76 cooperates with the pin to limit the extent of projection of the latch piston from its socket 22.
In FIGS. 8 and 9, the invention is shown as applied to a piston cylinder 57 having a pair of exhaust valves 58 operable in an internal combustion engine by a camshaft 60 of the non-overhead type. The exhaust valves are connected by a bridge 59. A rocker arm 61 is pivotable against the bridge to force the exhaust valves to open condition. The usual spring means 62 normally holds the valves closed. The rocker arm is pivotable about a shaft 63 relative to the bridge of the exhaust valves by means of one or the other of a pair of push rods 64 and 65 to which the rocker arm is connected in common. Push rod 64 carries a cam follower or lifter 66 which continuously rests upon a regular cam 67 of the camshaft. Cam 67 cooperates with the follower to lift the push rod 64 and pivot the common rocker arm 61 to cause the exhaust valves 58 to open at the usual or normal time in the cycle of the engine piston 68. The other push rod 65 carries at its end a lifter or tail-piece 69 having slidable movement in the engine block 70. A latch piston 72 is slidable in and out of a bore or socket 73 formed in the tail-piece. An auxiliary cam 74 also carried by the camshaft 60 is cooperable with this latch piston when the occasion demands to pivot the rocker arm 61 and cause opening of the exhaust valves at or about the end of a compression stroke of the piston 68 of the engine. The spring 26, anchored at 23 to the engine block 70, normally holds the latch piston within its socket clear of the rotating auxiliary cam. A pin 75, anchored in the tailpiece and extending into a slot of the latch piston 72, is cooperable with an end shoulder 76 of the slot to limit to a desired extent outward movement of the latch piston relative to the tail-piece 69 so that the latch piston may have proper cooperation with the auxiliary cam 74. The control valve unit 38 is shown as mounted in the engine block in this version of the invention. In the operation of this version of the invention, the regular cam 67 functions at the normal time in a cycle of the related engine piston to open the exhaust valves 58 to permit the escape of spent gases. When it is desired to retard the engines speed for breaking purposes, a related solenoid valve unit 29 is operated, causing the latch piston 72 to be hydraulically projected to the extent permitted by the pin '75 and locked outwardly of its socket in the path of the rotating auxiliary cam 74, as the hydraulic fiuid flows from the solenoid valve unit through the control valve 38 to the socket of the latch piston. The auxiliary cam 74 next cooperates with the projected latch piston to pivot the rocker arm 61 to open the exhaust valves at or about the end of the compression stroke of the piston of the engine. Following this camming action, the valve springs 62 function to re-close the exhaust valves following blow-down during the stroke succeeding the compression stroke. The regular cam 67 continues as usual, despite the projected condition of the latch piston 72, to cause opening of the exhaust valves at the usual time in the cycle of the piston 68 of the engine. De-energization of the solenoid valve unit causes the oil trapped at the rear of the latch piston to return through the control valve unit and solenoid valve unit to sump in the manner earlier explained.
In the foregoing applications of the invention, it is understood that fuel will not be wasted through the exhaust valves when they are caused to open and vent the piston cylinder of compressed air. The engine is equipped with customary fuel shut-oft" mechanism. The latter (not shown) may be conventional fuel metering means, a solenoid valve, or other suitable control operable upon release by the operator of the usual fuel control foot lever to shut off fuel flow to the engine.
It is to be further understood that the invention is also suited for use with spark plug engines.
What is claimed is:
1. In an internal combustion engine including a piston cylinder having an exhaust valve, a spring normally holding the exhaust valve closed, a rocker arm pivotable to open said valve, a rotatable camshaft, and a cam carried by the camshaft cooperable with the rocker arm to pivot the latter to open the exhaust valve at a normal time in the cycle of the piston in the piston cylinder, an auxiliary cam carried by the camshaft, a hydraulically actuable latch piston movable in a bore provided in the rocker arm, the latch piston having an hydraulically actuated condition wherein it projects from the rocker arm and in which condition the auxiliary cam has cooperation with the latch piston to pivot the rocker arm to open the exhaust valve at a time other than the said normal time, and the latch piston having a normal condition wherein it is retracted in the rocker arm and is disabled from such cooperation with the auxiliary cam to so pivot the rocker arm.
2. In an internal combustion engine as in claim 1, wherein return spring means constantly biases the latch piston to its normal condition.
3. In an internal combustion engine as in claim 1,
wherein the piston cylinder includes a plurality of exhaust valves and the rocker arm is common to and pivotable to open all of said exhaust valves.
4. In an internal combustion engine as in claim 1, wherein control means is provided for selectively controlling flow of hydraulic actuating oil to the latch piston and trapping it behind the latch piston.
5. In an internal combustion engine as in claim 4, wherein the control means comprises passage means connected below the latch piston with the latch piston bore, a hydraulic pressure oil supply line, a solenoid valve unit having an energized condition connecting the supply line with the passage means, a control valve unit in the passage means responsive to flow of pressurized oil from the solenoid valve unit into the passage means to allow oil flow through the passage means to the bore of the latch piston and to block return oil flow from the bore to the solenoid valve.
6. In an internal combustion engine as in claim 5, wherein a hydraulic pressure relief valve responsive to a predetermined maximum pressure in the passage means is provided in the control valve unit.
7. In an internal combustion engine as in claim 5, wherein the control means includes a relief port in the solenoid valve unit, the solenoid valve unit having a de-energized condition connecting the passage means with the relief port and sealing off the supply line, and the control valve unit being responsive to de-energization of the solenoid valve unit to connect the latch piston bore through the passage means with the relief port.
8. In an internal combustion engine as in claim 7, wherein a hydraulic pressure relief valve responsive to hydraulic pressure in the passage means above a predetermined minimum controls the relief port.
9. In an internal combustion engine as in claim 8, wherein a rocker arm shaft pivotally supports the rocker arm, the rocker arm shaft defines an internal chamber forming between the control valve unit and the solenoid valve unit part of the passage means, a lube line independent of the solenoid valve constantly supplies the internal chamber with hydraulic fluid at a pressure not exceeding said predetermined minimum, and there being fine orifices in the rocker arm shaft permitting bleeding of lubricant through the orifices to the rocker arm.
References Cited UNITED STATES PATENTS 2,002,196 5/1935 Ucko 12397 3,220,392 11/1965 Cummins 123-97 MARK NEWMAN, Primary Examiner.
RALPH D. BLAKESLEE, Examiner.