US3433209A - Engine overspeed control - Google Patents

Description

March 18, 1969 s. w. FREITAG ENGINE OVERSPEED CONTROL of A INVENTOR. 'lezm lykitag Sheet Filed July 28, 1967 POWER 2 SOURCE ATTQRNEY G. W. FREITAG ENGINE OVERSPEED CONTROL March 18, 1969 Sheet Filed July 28, 1967 ATTORNEY March 18, 1969 G. w. FRE-ITAG 3,433,209

ENGINE OVERSPEED CONTROL Filed July 28, 1967 sheet 3 of 4 ATTORN EY United States Patent 3,433,209 ENGINE OVERSPEED CONTROL Glenn W. Freitag, Woodridge, Ill., assignor to General Motors Corporation, Detroit, Mich, a corporation of Delaware Filed July 28, 1967, Ser. No. 656,831 US. Cl. 123-198 Claims Int. Cl. F02d 31/00, 23/02, 1/00 ABSTRACT OF THE DISCLOSURE An engine overspeed control including a mechanically actuated overspeed shutdown mechanism which acts to shut off fuel injection above a preset engine speed, an automatic reset mechanism which resets the shutdown mechanism to restore normal operation when engine has dropped to a predetermined safe level and manually actuated shutdown and lockout means which manually trip the overspeed shutdown mechanism and prevent actuation of the reset mechanism to secure a complete shutdown of the engine when desired. Both electrical and hydraulic systems for controlling the reset mechanism are disclosed.

Background of the invention This invention relates to engine protective mechanisms and more particularly to overspeed control means for an internal combustion engine arranged to provide protection against engine overspeed without complete engine shutdown but providing for manual selection of a shutdown function. g

It is known in the art to provide an internal combustion engine with means to stop the engine, such as by cutting off the fuel, whenever a predetermined maximum engine speed condition has been reached. One example of such an arrangement applied to a diesel engine comprises a camshaft carried fiyweight which, at a predetermined engine speed, moves outwardly under centrifugal force to actuate a trip lever so as to permit a spring actuated linkage to rotate cams against the fuel injector rocker arms, locking the arms in a depressed position and cutting olf fuel to the engine cylinders. The linkage includes an external, manually operated, reset lever by which the linkage may be returned to the latched position, permitting the resumption of normal engine operation.

While such an overspeed trip mechanism is intended primarily as a safety device to prevent the engine running away upon failure of the speed control system commonly provided, there are certain engine applications, for example in marine use as the main engine of a vessel, in which it is considered desirable that the engine should not completely stop due to an overspeed condition, 'but that continued operation of the engine is permitted for an indeterminate period thereafter. Additionally, the provision of an manually actuated emergency shutdown mechanism is desirable.

Summary The present invention contemplates the application to an engine, having overspeed shutdown mechanism, of means to automatically reset the shutdown mechanism after it has been tripped by an engine overspeed condition, and the engine speed has been reduced to a predetermined safe speed, so that normal engine operation may be resumed. To permit complete shutdown of the engine by the overspeed shutdown mechanism when desired, the invention provides manually actuated lockout means to hold the reset mechanism in the tripped position so as to prevent operation of the reset means. In addition, manual emergency shutdown of the engine is provided by including manual means to actuate the overspeed shut- 3,433,209 Patented Mar. 18, 1969 "ice down mechanism at will in conjunction with the lockout means to prevent operation of the reset means.

In order to provide broad utility of the invention, various specific mechanisms are included for arrangement in either electrically or hydraulically controlled systems, specific details of which are subsequently disclosed.

These and other features of the invention will be more readily apparent from the following description taken in connection with the accompanying drawings which form a part of this application.

Brief description 0 the drawings In the drawings,

FIGURE 1 is a fragmentary end view of an engine having an electrically actuated overspeed shutdown control system according to the present invention;

FIGURE 2 is a partially diagrammatic view of the engine of FIGURE 1 showing internal portions of the overspeed shutdown mechanism in the reset condition;

FIGURE 3 is a view similar to FIGURE 2, but showing the overspeed shutdown mechanism in the tripped posinon;

FIGURE 4 is an enlarged fragmentary view of the engine of FIGURE 1 showing details of the reset member, lockout means and manual shutdown means disposed in their normal operating positions;

FIGURE 5 is a fragmentary view similar to FIGURE 4 and showing the components in their tripped positions;

FIGURES 610 are schematic views showing a hydraulically actuated overspeed shutdown control mechanism according to the invention in various phases of operation.

Description of the preferred embodiments Referring now more specifically to the drawings wherein are disclosed preferred embodiments of electrical and hydraulic overspeed shutdown control systems according to the invention, FIGURE 1 illustrates an internal combustion engine of the diesel type generally indicated by numeral 12. As shown in FIGURES 2 and 3, engine 12 includes a pair of camshafts 14 which are connected to and rotatably driven by the usual crankshaft (not shown). The camshafts include earns 16 which actuate rocker arms 18 to reciprocate the plungers of fuel injectors 20 and thereby supply metered amounts of fuel to the engine cylinders. Balance weights 22 are mounted eccentrically at the ends of camshafts 14 and rotate therewith to comprise a part of the engine balancing system.

The engine includes overspeed shutdown mechanism arranged to shut off fuel to the engine cylinders when a predetermined maximum engine speed condition is reached or exceeded. This mechanism includes a series of rocker arm engaging pawls 24 pivotally mounted with spring biased cam followers 26 which are engaged by cams 28 mounted on trip shafts 30 extending parallel to camshafts 14. Shafts 30 are connected through suitable linkage 32 to a lever 34 biased downwardly by actuating spring 36 but normally retained in latched position as shown in FIGURE 2 by engagement of a trip lever 38 with a notch 40 located on a hub portion of trip lever 34. A fiyweight 42 is pivotally mounted on one of the balance weights 22 and is biased inwardly by a spring 44 to normally rotate with the balance weight 22, passing close to but spaced from the end of trip lever 38. The tension of spring 44 is adjustable by means of nuts 46 to vary the biasing force on the flyweight.

The portion of the mechanism so far described is known in the art and operates as follows. When the engine reaches a predetermined maximum speed condition, centrifugal force acting on fiyweight 42 overcomes the bias of spring 44 permitting the fiyweight to pivot 3 outwardly so that it strikes the end of trip lever 38. This dislodges lever 38 from notch 40 permitting spring 36 to actuate linkage 32, rotating shafts 30 to force cams 28 against followers 26 and biasing pawls 24 against rocker arms 18. When the camshafts 16 actuate the rocker arms to depress the plungers of injectors 20, pawls 24 engage notches 48 formed in the rocker arms holding the rocker arms in their depressed positions so that further reciprocation of the injector plungers and the resulting admission of fuel to the engine cylinders is prevented. This condition is shown in FIGURE 3.

Surrounding the balance weights and portions of the overspeed shutdown mechanism at the end of the engine is a housing 50 closed by a cover 52 having spaced cylindrical openings over the individual balance weights, the openings being closed by covers 54 and 56. Extending through cover 52 are shafts 58 and 60 which are rotatably fixed to levers 34 and 38 respectively, located internally of housing 50.

Externally of cover 52 a reset lever 62 is secured to shaft 58 by a hub portion 64 which, as best shown in FIGURES 4 and 5, includes a notch 66 and an extending abutment 68. Lever 62 rotates with shaft 58 and is adapted to be rotated in a counterclockwise direction, as shown in the figures, to reset the overspeed shutdown mechanism in its latched position after it has been tripped. Inboard from the end of shaft 60 a manual shutdown lever 70 is fixed. Actuation of lever 70 in a clockwise direction rotates trip lever 38, initiating actuation of the overspeed shutdown mechanism in the same manner as if an engine overspeed condition had occurred.

Pivotally mounted on the end of shaft 60 adjacent lever 70 is a lockout lever 72 having adjacent its center a notch 73 and at one end a latch portion 74 adapted to engage notch 66 of the reset lever hub to hold the reset lever in the tripped position as shown in FIGURE 5. At the other end of lever 72 is a tail 76 which receives one end of a coil spring 78. Lever 70 includes an extending portion 80 to which is secured a pin '82 pivotally carrying a lockout trip lever 84. Lever 84 has at one end a latch portion 86 adapted to engage notch 73 of the lockout lever 72 to prevent its engagement with notch 66 of the reset lever. At its other end, lever 84 has a platform-like tail 88 having secured thereto one end of a manual pull cable 90 and receiving the other end of coil spring 78. Tail 88 also includes an extending tang or abutment 92 which upon clockwise rotation of lever 84 is adapted to engage portion 80 of lever 70.

The above-described mechanism operates as follows. When the engine is running normally, as shown in 'FIG- URE 4, actuation of pull cable 90 rotates lever 84 in a clockwise direction removing latch portion 86 from notch 73 and permitting spring 78 to force lever 72 clockwise into engagement with hub 64 of the reset lever 62. Upon further movement of lever 84, tang 92 engages portion 80 of lever 70 rotating it clockwise and moving lever 38 so as to trip the overspeed shutdown mechanism, thereby shutting oif the fuel to the engine cylinders as previously described. Upon tripping of the overspeed shutdown mechanism, lever 62 is rotated clockwise to the tripped position wherein latch portion 74 of lever 72 engages notch 66 holding the reset lever 62 in the tripped position and causing the engine to stop. This condition is shown in FIGURE 5.

FIGURES 1-3 disclose an electrically actuated reset mechanism applied to the previously described engine.

cating oil pump 108 and a drain connection 110 is provided to return excess lubricating oil from the solenoid valve 104 to the interior of the engine. The solenoid valve is electrically connected in series with a normally open limit switch 112, a normally closed limit switch 114, a speed sensing switch 116 and a source of alternating current 118. Limit switch 112 is carried on cover 54 and is normally engaged by abutment 68 of the reset lever 62, holding the switch in the open position. Limit switch 114 is carried on portion of shutdown lever 70 and is normally engaged by tail 88 of lockout trip lever 84, holding the switch in the closed position. Speed sensing switch 116 is connected to an engine driven tachometer generator 120 which generates a voltage proportional to engine speed. Switch 116 is arranged to be open above a predetermined normal engine speed and to be closed below a second predetermined normal speed less than the first.

The operation of the electrically actuated system is as follows. If the engine overspeeds, the overspeed shutdown mechanism is tripped, as previously described, rotating lever 62 clockwise as permitted by lost motion connection 98. This closes limit switch 112. Limit switch 114 is already closed but, since engine speed is above the setting of switch 116, solenoid valve 104 remains deenergized. The cut off engine fuel by the overspeed shutdown mechanism causes the engine to drop and, when it reaches the setting of switch 116, the switch closes completing the circuit to, and energizing, solenoid valve 104. This operates the solenoid valve to direct pressure oil from connection 106 through connection 102 against piston 96 and to drain oil on the other side of the piston through connection and drain line 110. lPiston 96, thus, moves leftwardly rotating lever 62 to its reset position and returning the engine to normal operation. When lever 62 reaches the latched position, limit switch 112 opens, de-energizing solenoid valve 104 which then returns to its original position permitting pressure oil from line 106 to pass through line 100 to the left side of the piston and draining oil on the right side through line 102 and drain line 110. This returns the ram to its ready position but has no effect on lever 62 due to the lost motion connection 98.

Limit switch 114 does not operate except in the case of a manual shutdown of the engine by actuation of pull cable '90 as previously described. In such an instance, clockwise movement of lever 84 opens limit switch 114 preventing the energizing of solenoid valve 104 so that complete shutdown of the engine takes place without actuation of the hydraulic ram 94.

FIGURES -6-l 0 disclose schematically the arrangement of an alternative hydraulically actuated overspeed shutdown control system which may be utilized instead of portions of the electrically actuated system previously described. Certain elements in these figures are identical to those previously described and are identified by identical reference numerals. These includes the overspeed reset lever 62, the hydraulic ram 94 with its associated components including lost motion connection 98, connecting lines 100 and 102, supply and drain lines 106 and 110, each of which have various branches, and lubricating oil pump outlet 107.

The system also includes a number of components different from those of the electrically actuated system. For example, a hydraulically actuated free-spool fourway valve 122 replaces solenoid valve 104. Valve 122 connects with lines 100, 102, 106 and and controls flow through these lines to and from the hydraulic ram in the same manner as the solenoid valve 104. It is, however, operated hydraulically and for this purpose is connected at one end through line 124 with a three-way return valve 126. Valve 126 is also connected with pressure line 106 and drain line 110 and is spring biased to normally connect line 124 to drain. The valve is actuated by lever 62 only when the lever is in a position of slight overtravel from normal latching so that in the latched position, lever 62 does not quite actuate valve 126, leaving it in its normal position.

At its other end, four-way valve 122 is connected through line 128 to a second three-valve 130 acting as a trip valve. Valve 130 is also connected to drain line 110 as well as to a supply line 132. It is spring biased to normally connect line 128 to drain and is actuated to connect lines 128 and 132 by contact with the reset lever 62 only when the lever is in the tripped position. Trip valve 130 connects through line 132 with a third three-way valve 134 which may be called a speed valve. Valve 134 is spring biased to normally connect line 132 with pressure line 106 but it is actuated by a hydraulic signal in a pilot line 136 to connect line 132 to drain line 110. Line 136 is fed by an overspeed governor 138 which is driven directly by the engine at speeds proportonal to engine speed. It is arranged to supply a pressure signal to pilot line 136 whenever engine speed rises above a predetermined setting and to discontinue the pilot signal when the speed falls below a second setting somewhat less than the first.

Operation of the hydraulic system is as follows. In the normal running condition, as shown in FIGURE 6, reset lever 62 is rotated counterclockwise in its latched condition close to but not actuating valve 126 and away from valve 130. Four-way valve 122 is in its leftward position connecting pressure line 106 through line 102 with the lower part of ram 94 so as to hold the piston 96 upwardly in its retracted or ready position as shown in the figure. Line 100 is connected to drain 110. Both ends of four-way valve 122 are also connected to drain, the right end through line 124 and valve 126 and the left end through line 128 and valve 130 so that valve 122 remains in the leftward position. As long as engine speed remains below the setting of overspeed governor 138, no pilot pressure is supplied to line 136 and, accordingly, line 132 is connected to pressure supply line 106. However, this connection has no eflfect in this condition since it is discontinuous at valve 130.

If engine speed rises to an overspeed condition, the overspeed shutdown mechanism trips, moving reset lever 62 clockwise as shown in FIGURE 7. This movement rotates lever 62 completely away from valve 126 and into actuating contact with valve 130 connecting line 128 with line 132. However, the increase in engine speed prior to tripping the overspeed shutdown mechanism has caused overspeed governor 138 to apply a pilot signal through line 136 to valve 134, actuating it downwardly and connecting line 132 to drain so that no further action occurs at this time and engine speed falls due to the shut off of fuel by the overspeed shutdown mechanism.

"When engine speed has dropped to the predetermined speed setting of governor 138, the governor cuts off the signal to line 136 permitting valve 134 to move upwardly, as shown in FIGURE 8, so as to connect pressure line 106 with line 132 and supply pressure oil through valve 130 and line 128 to valve 122. This moves valve 122 to its rightward position connecting line 106 through line 100 with the upper part of ram 94 so as to apply a downward pressure on piston 96. At the same time, line 102 is connected to drain relieving pressure on the underside of piston 94.

Piston 96 of the reset ram then begins to move downwardly as shown in FIGURE 9 wherein it is seen that lost motion connection 98 has engaged reset lever 62 and moved it approximately halfway toward its latched position. As the reset lever is moved away from the tripped position, it moves out of contact with valve 130 connecting line 128 to drain and relieving pressure on the left side of valve 122. Valve 122 still remains in the rightward position, however, since its right end is still connected to drain.

Piston 96 moves downwardly as shown in FIGURE 10 to its fully extended position at which point reset lever 62 has been moved slightly beyond the latched position to a position of slight overtravel. In this position lever 62 actuatingly contacts valve 126 moving it downwardly so as to connect pressure line 106 through line 124 with the right end of valve 122. This moves valve 122 again to its leftward position connecting the upper end of ram 94 to drain and again supplying pressure oil to the lower end. This then causes piston 94 to move upwardly to its ready position and re-establishes the normal operating condition of FIGURE 6.

The above-described hydraulic system difiers functionally from the electrical system previously described in the case of a manual shutdown, although the same result is reached. The difference is that in the hydraulic system prevention of the resetting function is obtained by relying completely on the engagement oflockout lever 72 with notch 66 of the reset lever 62 to prevent the ram from resetting the overspeed shutdown mechanism. While it would be possible to place in the hydraulic system a cut out device to forestall the attempted resetting action of the ram whenever a manual shutdown is initiated, as is done by limit switch 114 in the electrical system, such an added device has not been found to be necessary and,

- thus, is not included in the hydraulic system.

While applicants invention has been presented by reference to specific embodiments incorporating certain specific aspects of the invention, it is obvious that numerous modifications or changes could be made within the scope of the inventive concept as herein disclosed and it is, accordingly, intended that the invention should not be limited except as defined by the following claims.

I claim:

1. In combination with an internal combustion engine, overspeed control means comprising overspeed shutdown mechanism actuable in response to engine operation above a predetermined maximum engine speed to shut off fuel to the engine,

a movable reset member having a tripped position and a reset position, said member being connected with said shutdown mechanism such that actuation of said mechanism to shut off engine fuel moves said member to said tripped position and return of said member to said reset position resets said mechanism to again permit normal fuel flow to the engine and reset means responsive to engine operation below a second predetermined engine speed less than said maximum speed to actuate said reset member into said reset position whereby complete engine shutdown due to an engine overspeed is avoided.

2. The combination of claim 1 and further including manually actuable lockout means to hold said reset member in the tripped position so as to prevent actuation of said member by said reset means whereby complete engine shutdown may be accomplished by actuation of said overspeed shutdown mechanism.

3. The combination of claim 2 and further comprising manually actuable emergency shutdown means to actuate said overspeed shutdown mechanism and means adapted to actuate both said lockout means and said emergency shutdown means by a single action.

4. In combination with an internal combustion engine having a source of pressure fluid, overspeed control means comprising overspeed shutdown mechanism actuable in response to engine operation above a predetermined maximum engine speed to shut off fuel to the engine,

a movable reset member having a tripped position and a reset position, said member being connected with said shutdown mechanism such that actuation of said mechanism to shut off engine fuel moves said member to said tripped position and return of said member to said reset position resets said mechanism to again permit normal fuel flow to the engine,

a fluid actuated ram secured to said engine and connected with said reset member through a lost motion connection permitting said reset member to move to the tripped position, said ram being connected with said source of pressure fluid for actuation thereby to return said reset member to the reset position and means to control the flow of pressure fluid to said ram, said fluid control means being responsive to engine operation below a second predetermined engine speed less than said maximum speed to permit fluid actuation of said ram to reset said shutdown mechanism whereby complete engine shutdown due to an engine overspeed is avoided.

5. The combination of claim 4 wherein said fluid control means comprises an engine driven electric generator having an output varying with engine speed,

a speed switch connected with said generator output and responsive thereto to open above a predetermined engine speed intermediate said maximum and second predetermined speeds and to close below said second predetermined engine speed,

a trip switch arranged to be actuated by said reset member so as to be open when said member is in the reset position and closed at other times and an electric solenoid valve connected with said pressure fluid source and said ram and arranged such that when said solenoid valve is energized it directs pressure fluid to actuate said ram in a resetting direction,

said solenoid valve, said trip switch and said speed switch being connected in series with an electric power source so as to energize said solenoid valve whenever said switches are closed.

6. The combination of claim 5 and further including manual shutdown means comprising manually actuable lockout mechanism engageable with said reset member to hold said member in the tripped position so as to prevent resetting of said overspeed shutdown mechanism by said ram,

manually actuable emergency shutdown mechanism to actuate said overspeed shutdown mechanism and mechanical actuating means to actuate both said lockout mechanism and said emergency shutdown mechanism by a single mechanical action.

7. The combination of claim 6 and further including a manual shutdown indicating switch arranged to be actuated by said manual shutdown means such that said indicating switch is open whenever said manual shutdown means is actuated to shutdown said engine and said indicating switch is closed at other times,

said indicating switch being connected in series with said solenoid valve, said trip switch and said speed switch whereby, upon actuation of said manual shutdown means, said indicating switch opens preventing the energizing of said solenoid valve so as to forestall resetting of said overspeed shutdown mechanism by said ram.

8. The combination of claim 4 wherein said fluid control means comprises an engine driven hydraulic overspeed governor having a fluid pressure output varying with engine speed,

a speed valve connected with said governor output and responsive thereto to move to a first operative position during engine operation below said second predetermined speed and to move to a second operative position during engine operation above a predetermined engine speed intermediate said maximum and second predetermined speeds,

a trip valve arranged to be actuated by said reset member so as to move to a first operative position when said resetmember moves away from its reset position and to move to a second operative position when said reset member moves to its reset position and a hydraulic selector valve connected with said pressure fluid source and said ram and having a first operative position in which it directs pressure fluid to actuate said ram in a resetting direction and a second operative position in which it directs pressure fluid to actuate said ram in a returning direction,

said speed valve and said trip valve being connected in series intermedite said pressure fluid source and said hydraulic selector valve such that When both said speed valve and said trip valve are in their first operative positions pressure fluid is directed to said hydraulic selector valve moving it to its first opera tive position and causing actuation of said ram to reset said overspeed shutdown mechanism.

9. The combination of claim 8 and further comprising a return valve normally positioned in a first operative position and arranged to be actuated by said reset member so as to move to a second operative position during overtravel of said reset member beyond its reset position, said return valve being connected with said pressure fluid source and said selector valve and arranged in said first operative position to drain fluid from said selector valve to permit actuation of the selector valve to its first operative position and said return valve being arranged in its second operative position to direct pressure fluid to said selector valve to move said selector valve to its second op erative position and thereby cause actuation of said ram in a returning direction.

10. The combination of claim 8 and further including manual shutdown means comprising manually actuable lockout mechanism engageable with said reset member to hold said member in the tripped position so as to prevent resetting of said overspeed shutdown mechanism by said ram,

manually actuable emergency shutdown mechanism to actuate said overspeed shutdown mechanism and mechanical actuating means to actuate both said lockout mechanism and said emergency shutdown mechanism by a single mechanical action.

Engine Maintenance Manual No. 252c for Model 567c Engines, First Edition, March 1954, Electromotive Division, General Motors Corp., LaGrange, 111., pp. 603, 605, and 606.

WENDELL E. BURNS, Primaly Examiner.

US. Cl. X.R.

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