US2764965A - Hydraulic governors - Google Patents

Description

Oct. 2, 1956 J. E. TUSCHER 2,764,965

HYDRAULIC GOVERNORS Filed May 17, 1954 6 Sheets-Sheet 1 INVENTOR.

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BY MM M 4PM Oct 1956 J. E. TUSCEHER 2,764,965

HYDRAULIC GOVERNORS Filed May 17, 1954 6 Sheets-Sheet 5 n n, n

INVENTOR JEAN EDOUARD TUSCHER BY WyM Oct. 2, 1956 J. E. TUSCHER 2,764,965

HYDRAULIC GOVERNORS Filed May 17, 1954 6 Sheets-Sheet 6 INVENTOR JEAN EDOUARD TUSC HER United States Patent C) HYDRAULIC GOVERNORS Jean Edouard Tuscher, Ivry-sur-Seine, France, assignmto Sebem S. A., Neuchatel, Switzerland, a corporation of Switzerland Application May 17, 1954, Serial No. 430,323

Claims priority, application Switzerland May 21, 195 3 9 Claims. (Cl. 123-140) The object of the present invention is an improved all speed hydraulic governor for internal combustion engines with fuel injection of the type described in U. S. application Serial No. 217,711 of the 27th of March 1951, in which the passage opened by the valve of the governor piston simultaneously governs the running condition as a function of the resisting torque and the speed characteristic of the governor as a function of the various running conditions of the engine. The governor constituting the object of the invention is characterized by the fact that it comprises means to increase the rate of injection for the intermediate running conditions, means to modify the speed characteristic for the various running conditions according to a predetermined law, means to limit the speed characteristic at the idling speed of the engine, means to increase the rate of injection automatically when the engine is started, means to govern the rate of injection for the upper speed limit of the engine, and means for limiting at a predetermined value the pressure in the hydraulic circuit of the governor.

The accompanying drawing illustrates, by way of example, an embodiment of the governor according to the invention and shows various diagrams illustrating its operation.

Fig. 1 is a vertical axial section of the governor.

Fig. 2 is a horizontal axial section of the governor.

Fig. 3 is a side view showing the control levers in the position corresponding to the limit speed.

Fig. 4 is the same side view showing the control levers in the stop position.

Fig. 5 is a back view of the governor.

Fig. 6 is a view from above of the governor with the upper cover removed.

Fig. 7 is a diagram showing the power and torque curves of a diesel engine as a function of the engine speed, and the corresponding curves of the rate of delivery of the injection pump when the delivery rate stop is fixed or variable according to the pressure upstream of the governor piston.

Figs. 8 and 9 show two modifications of the lever controlling the speed characteristic.

Fig. 10 illustrates, as a function of the running conditions, the aspect of the variation of the speed characteristic corresponding to the profiles of the two levers of Figs. 8 and 9.

Fig. 11 is a diagram showing, for the two same profiles of the speed characteristic lever, the positions of the rack of the injection pump between full load and excess no 7 load speed as a function of the various running conditions ranging from the idling speed to the upper limit speed of the engine.

Fig. 12 shows, again for the same two profiles of the speed characteristic lever, the power curves of a diesel engine at /2, A, and full load and the aspect of the cuts at the upper limit speed and at the intermediate running conditions.

In its application to diesel engines the hydraulic governor according to the U. S. application Ser. No. 217,711

2,7 64,965 Patented Oct. 2, 1956 ice '2 of the 27th of March, 1951, comprises a casing 1 comprising a volumetric pump, which is shown as agear pump 50 with gears 51 and 52, driven by the injection pump, indicated by the end of the rack 2 of which is indicated, controlling the rate of injection (Fig. 1).

The volumetric pump functions in a closed circuit and the discharge pressure thereof acts through a duct 3 on a piston 4 within a cylinder in casing 1, the pressure being opposed by a spring 5. The end of the governor "piston 4 is provided with an eccentric port cooperating with a port in a shutter 6, which moves with the piston, in order to form an adjustable passage S in the closed circuit, which circuit extends to the volumetric pump inlet 7.

A rod 8 of the piston 4 controls the position of the rack 2 through a link 9, a lever 10 and 'a sleeve 11. On the other hand, the section S at the valve 6 is controlled by the position of an accelerator 12, which, by means of a beam 13 acting on two levers 1'4 and 15 on either end of beam 13, simultaneously determines:

on one side, by modifying by means of lever 14 the angular position of the valve shutter 6 in relation to the piston 4, a section of the passage S which defines a speed of rotation of the engine,

and on the other, by modifying by lever 15 the angular position of a slotted member 16 which is attached to lever 15, the rotation of the piston 4 in the course of its governing stroke, in order to modify in one sense or the other the same section S, so as to obtain the speed characteristics suited to the various running conditions.

The relative angular positions of the piston 4 and the valve 6 are thus both determined by the positions of the accelerator 12 regardless of the running condition and regardless of the load which causes a resisting torque on the engine. 7

If when the governor functions, and for any given position of the accelerator 12 the resisting torque happens, for instance to decrease, the speed of the engine increases, causing an increased rate of delivery and an increased pressure from the volumetric pump, and the piston 4 moves to the right thus moving the rack 2 also to the right towards the stop position, so as to re-es'tablish the running condition determined by the position of the accelerator 12 for the new resisting torque. The contrary happens when the resisting torque increases.

Depending on the position of the accelerator 12 which determines a given section of the passage S at the valve shutter 6, the slotted member 16, in whose slot slides a button 17 of the piston 4, causes the said piston to eflect a rotation corresponding to a positive '(Fig. 3) or to a negative (Fig. 4) angle relative to the axis of the position in the course of its governing stroke, depending on the running condition imposed to the engine by the position of the accelerator 12.

If, in the course of the governing stroke of the piston 4, and when a reduction of the resisting torque occurs, the rotation of the piston in relation to the shutter valve causes an increase of the section S (Fig. 4), the speed characteristic or degree of irregularity of the governing action thus effected is greater than that of the spring 5 when the slot of the member 16 is parallel to the aids of the piston 4, i. e. when the latter does not rotate. This means that the dilference in speed between the two positions considered increases when the section S increases during the governing stroke. I

On the other hand, if the angle of the slotted member 16 is positive (Fig. 3), the section S decreases during the governing stroke, the degree of irregularity is then less than that of the spring 5 and the diiference in speed between the two positions considered decreases as S decreases. v

The aspect of the variation of the speed characteristic is thus determined by the profile of the cam surface of the lever 15, which, under the action of a spring 18,

rests against a speed characteristic adjusting screw 19 on two positions of the governor, to the mean speed at which the governing action occurs.

2'- 1) z 1 1+ 2 menn where m and m are the lower and upper speeds of rotation, and m and w, the corresponding angular speeds.

The Figs. 8 and 9 show, by way of example, two embodiments of the lever 15, and the variation in the speed characteristic obtained by these two profiles is illustrated in Fig. 10.

The variation obtained with the lever Fig. 8 is shown by the full curve (Fig. 10) which intersects the axis of the abscissae at a point corresponding to a speed which is very near the limit speed 113 of the engine. The speed characteristic, or, if preferred, the difference in speeds corresponding to the various governing positions, de-

creases practically linearly from the idling speed 711' to the limit speed n3 of the engine.

The lever 15 of Fig. 9 gives a very different speed characteristic curve (shown in dots and dashes). The degree of irregularity decreases very rapidly from the idling speed 111' up to the speed In and then continues to decrease, but very slowly, up to the limit speed m. This curve is particularly suitable for engines used for traction purposes, having a range of utilisation under load comprised between the speeds in and In. Between these two running conditions the difference in speed between full load and no load is slight, and this gives the engine considerable flexibility. The speed characteristic curve no longer intersects the axis of the abscissae, where the degree of irregularity e is zero and the governing efiect consequently indiiferent. The adjustment of a limit speed stop 20 (Figs. 3 and 4) may then be efiected without the risk'of touching the zero degree of irregularity.

The positions, corresponding to the rates of delivery, assumed by the rack 2 of the injection pump as a function of the running conditions are shown in Fig. 11 by full and by dot-and-dash lines, respectively corresponding to the two speed characteristic curves in Fig. 10, whereas the corresponding power curves of an engine used for traction purposes at full, three quarters and half load and the cut-elf curves for the various running conditions under which the engine is used are shown in Fig. 12.

This last diagram clearly illustrates the advantage afforded, in the case of an engine used for traction purposes, by a governing eifect with a small degree of irregularity over the whole range of utilisation (dot-anddash curves corresponding to the speed characteristic lever Fig. 9). It may be seen that for the whole range of utilisation, the difference in speed between full load P and no load P0 is very small, the engine instantaneously responding to every variation of the resisting torque, thus giving a vigorous acceleration. In addition, because of the fact that the specific fuel consumption decreases in a marked manner between full load P and half load P/2, the result is a fuel economy of the order of 20%.

The examples of Figs. 8 and 9 relate to linear cam surface profiles, but it is clear that the profile of the lever 15 could be given any desired curvature, in order to obtain a given speed characteristic curve. For instance, it might be desired to obtain a curve for electric generating sets designed to furnish a current of or 60 cycles with the same degree of irregularity at the two corresponding running conditions.

The degree of irregularity at the idling speed is limited by an adjustable screw 21, mounted in casing 1, which at idling speed rests against a projection of the speed characteristic lever 15, thus preventing it from following the movement of the beam 13 when the accelerator 12 is moved from the idling speed to the stop position (Fig. 4).

This adjustment of the degree of irregularity at idling speed enables the minimum degree of irregularity required to obtain a steady idling speed of the engine to be measured, and consequently enables the moment of inertia of the rotating masses to be determined. On the test bed, this minimum degree of irregularity is reached as to the stop 21 is screwed in, the rack 2 of the pump begins to show a tendency to hunt.

During the motion of the accelerator 12 from the idling speed to the stop position, an adjustable screw 22 on the beam 13 lifts an arm 23 on a lever 24, pivoted on the casing, which, in its turn lifts a delivery rate adjusting screw 25 fixed to a member 26 articulated on a pin 27 on the lever 10 of the rack 2, in such a manner that for the stop position of the accelerator, the said screw 25 disengages a delivery rate stop 28 and allows the rack 2 to move to an overload position with the engine stopped and when the pressure in the governor disappears (Fig. 4). This overload starting position of rack 2 may be adjusted by a screw 29 on the lever 10. The tie, the length of which is adjustable, connecting the rack 2 to the pin 27 on the lever 10 is formed by a fork 30, articulated on a pin of the rack 2, a sleeve 11 screwed onto a threaded rod of the fork 30 and fitted with a spring 31 to prevent backlash, and a screw 32 pressed by the said spring and forming part of a tie member 33 articulated on the pin 27 on the lever 10, so that the blocking of a lock nut 34 against the sleeve does not cause torsion to be exerted either on the rack 2 or on the lever 10 of the governor (Fig. 6).

When the accelerator is suddenly brought back from the high speed to the idling speed position, which implies the instantaneous closing of the section S in the shutter valve 6, the pressure on the upstream side of the piston may rise to values which are too great to be contained by the components of the governor. In order to avoid these dangerous pressures, a by-pass valve 35 is placed in the governor pump, this being made possible by the fact that the governor always operates between the same pressure limits, whatever the various running conditions of the engine may be. This valve 35 is loaded by a spring 36 in such a manner that the maximum pressure in the circuit is limited to a value which is slightly higher than the highest governing pressure.

The opposing thrusts of the piston 4 and of the spring 5 are taken up by aball race 37 which permits angular motion of the piston in relation to the rod 38, which rod does not follow the rotary motion of the piston 4 during the governing action, to take place with a minimum of friction.

The characteristic rate of delivery curve of a piston injection pump is illustrated in Fig. 7 by the curve Q, which shows that the rate of delivery increases with the speed of rotation n, because for the same injection pressures, the leaks are more important at low speeds than at high speeds. On the contrary, the amount of fresh air filling the cylinders of the engine decreases with the speed of rotation.

In order to correct this anomaly, and to enable the engine to develop the power corresponding to the amount of fresh air contained in its cylinders under all running conditions, the delivery rate stop 28, which acts to limit the travel of the rack 2, and consequently to limit the rate of injection, is elastically mounted in its housing by means of a spring 38 which can give for a given distance and according to a predetermined law under the thrust of the delivery rate adjusting screw 25. Let us now suppose that the accelerator 12 is on the maximum speed stop 20 (Fig. 3). When the delivery rate screw 25 comes into contact with the stop 28, which is assumed to be fixed, the maximum power P3 of the engine for the running condition n3 'is reached and theinjec tion pump gives its maxifnntri delivery (Fig. 7). If the resisting torque acting on the engine increases, the power curve 1 corresponding to the rate of delivery curve Q of the injection pump is raised. The passage section S3 at the valve .6 does not change, the accelerator having remained on the stop 20 corresponding to the limit speed as.

In order to reestablish the rate of delivery .over the whole range of speeds from n3 to r11, or even ,to enrich it, if the amount of air contained in the cylinders allows it, it is sufficient to allow the rack 2 to be moved in the direction of the larger rates ,of delivery ,(towards the left). The limit value a of this displacement will be indicated for the speed it by the appearance of smoke in the exhaust of the engine.

The section S3 being known, the pressures P3, P2 and P1 corresponding to the speeds n3, I22 and m (Fig. 7) can be calculated. These pressures may also be measured with a pressure gauge. The pressure p; multiplied by the surface of the piston 4 gives the force of equilibrium R3 of the efforts exerted by the piston 4 and the spring 5 at the limit speed m. The thrusts R2 and R1 of the piston for the pressures p2 and 111 are calculated in the same manner. The differences give the effort exerted by the link 9 on its point of attach ment to the lever 10 for the speeds n2 and m.

If it is desired to enrich the rate of delivery Q of the injection pump over the whole range of speeds between 11 and m, it is sufficient to reduce the displacement a of the rack and the force AR1 to the delivery rate adjusting screw 25 in proportion to the ratios of the lever 10 in order to find a stroke at and a force F1 at the delivery rate stop 28. The spring 38 of the resistance necessary in stop 28 is then determined. Its initial thrust is Zero and its constant is equal to F 1/ a1.

The delivery rate curve Q for the injection pump and the power curve P' for the engine (dotted lines, Fig. 7) are then obtained on the test bed.

If the enrichment of the rate of delivery is only to begin at an intermediate speed n2, the spring 38 will be given an initial thrust F2 which is calculated from the disequilibrium AR2. If the rate of delivery enriching stroke on the rack is :11, then the constant of the spring 38 will be FZ-Fl (dot-and-dash curves Q" and P).

On the same Fig. 7 the variations of the torque of the engine corresponding to these settings are shown by the three curves C, C and C".

The initial thrust of the spring 38 may be adjusted by means of the threaded stop 39, whereas the stroke at is limited by the adjustable screw 40.

What I claim is:

1. An all speed hydraulic governor for an internal combustion engine having a fuel injection pump and a volumetric pump, said governor comprising a casing having a cylinder therein with an inlet from and an outlet to said volumetric pump, a piston slidable in said cylinder between said inlet and said outlet and having a valve therein, means on said governor actuated by said piston to regulate said fuel injection pump, means acting on said regulating means to permit an increase in the rate of injection of said fuel injection pump, means on said governor actuated by said engine to adjust the opening of said valve in accordance with the speed of said engine, said means further adjusting the opening of said valve in accordance with predetermined speed characteristics for various speeds of said engine, stop means on said casing to limit said further adjustment of the opening of said valve at the idling speed of said engine, means actuated by said valve opening adjusting means to free said fuel injection pump from regulation by said piston when said engine is stopped and to permit said fuel pump to increase its rate .of injection, means to adjust the regulation of said fuel injection pump to permit regulation of the rate of fuel injection at the maximum speed of said engine, and means in said volumetric pump to limit the pres sure in said inlet, outlet, cylinder and volumetric pump.

2. An all speed hydraulic governor for an internal combustion engine having a fuel injection pump and a volumetric pump driven by said fuel injection pump, said governor comprising a casing having a cylinder therein with an inlet from and an outlet to said volumetric pump, a piston slidable in said cylinder between said inlet and said outlet having a valve therein, a rack regulating the rate of fuel injection of said fuel pump, a linkage, one end of which is pivoted on said governor, pivotally connected to said rack, a link .between said piston and said linkage, whereby said linkage is moved in response to movement of said piston to regulate said fuel injection pump, means acting on said linkage to permit an increase in the rate of injection of said fuel injection pump, means on said governor actuated by said engine to adjust the opening of said valve in accordance with the speed of said engine, said means further adjusting the opening of said valve in accordance with predetermined speed characteristics for various speeds of said engine, stop means on said casing to limit said further adjustment of the opening of said valve at the idling speed of said engine, means actuated by said valve opening adjusting means to free said linkage from actuation by said piston when said engine is stopped and to permit said fuel pump to increase its rate of injection, means in said linkage to adjust the linkage to permit regulation of the rate of fuel injection at the maximum speed of said engine, and means in said volumetric pump to limit the pressure in said inlet, outlet, cylinder and volumetric pump.

3. A governor as claimed in claim 2 in which said means acting on said linkage to permit an increase in the rate of injection comprises a delivery rate adjusting screw carried by said linkage, a delivery rate stop slidably mounted on said casing abutted by said adjusting screw, said stop being adjustable in the direction of its sliding and having spring means thereon permitting movement of the stop under the action of said screw and linkage, said movement being in accordance with predetermined pressures on said piston brought about by increases in the load on said engine, whereby said linkage is permitted to move to increase the rate of fuel injection.

4. A governor as claimed in claim 3, said spring having a strength corresponding to a predetermined pressure on said piston at a predetermined running condition of said engine, whereby said spring prevents movement of said stop and a corresponding increase in the fuel injec tion rate until the predetermined running condition is reached.

5. A governor as claimed in claim 2 in which said means to further adjust the opening of said valve comprises a member rotatably mounted in the wall of said cylinder adjacent said piston, said member having a slot in the end thereof adjacent said piston, a pin on said piston slidable in said slot and a speed characteristic lever having a speed characteristic cam surface thereon attached to said member, said cam surface having a profile which will adjust said piston and valve opening to produce a predetermined speed characteristic curve for said engine, said cam surface being acted on by said means actuated by said engine.

6. A governor as claimed in claim 5 in which said stop means on said casing to limit further adjustment of the opening of said valve comprises a stop abutted by said speed characteristic lever to prevent movement of said lever past a point at which said engine idles.

7. A governor as claimed in claim 3 in which said means to free said linkage from actuation by said piston when said engine is stopped comprises an adjustable 7 screw on said means actuated by said engine, a disengaging lever pivoted on said casing and acted on by said adjustable screw, a delivery rate adjusting screw carrier lever on which said delivery rate adjusting screw is carried pivoted to said linkage to position said delivery rate adjusting screw in abutment with said delivery rate stop, the free end of said carrier lever positioned to be acted on by the free end of said disengaging lever,. whereby when said engine stops said means actuated by said engine moves said disengaging lever to swing said delivery rate adjusting screw carrier lever to move said delivery rate adjusting screw out of engagement with said delivery rate stop.

8. A governor as claimed in claim 2 in which said means to adjust the linkage to permit regulation of the rate of fuel injection at the maximum speed of said engine comprises an adjustable connection between said linkage and said rack consisting of a fork having a threaded free end, said fork pivoted to said rack, a hollow sleeve threaded to said free end and having an opening at its other'end, a lock nut on said free end bearing against'said sleeve, a screw within said sleeve projecting therefrom through said opening and screwed to said linkage, and a spring within said hollow sleeve urging said screw out of said cylinder.

9. A governor as claimed in claim 2 in which said means to limit pressure in the inlet, outlet, cylinder and volumetric pump comprises an adjustable relief valve.

References Cited in the file of this patent UNITED STATES PATENTS 2,177,120 Schaeren Oct. 24, 1939 2,222,919 Trapp Nov. 26, 1940 2,675,795 Links Apr. 20, 1954 FOREIGN PATENTS 238,213 Switzerland Oct. 16, 1945 272,061 Switzerland Feb. 16, 1951

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