US2929334A - Variable-output hydraulic generator - Google Patents

Description

' March 22, 1960 J. PANHARD 2,929,334

VARIABLE-OUTPUT HYDRAULIC GENERATOR Filed June 10, 1957 s Sheets-Sheet 2 March 22, 1960 J. PANHARD 2,929,334

VARIABLE-OUTPUT HYDRAULIC GENERATOR Filed June 10, 1957 3 Sheets-Sheet 3 United States Patent-*- VARIABLE-OUTPUT HYDRAULIC GENERATOR Jean Panhard, Paris, France, assiguor to Societe Anonyme des Anciens Etablissements Panhard & Levassor, Paris, France Application June 10, 1957, Serial No. 664,743

Claims priority, application France June 11, 1956 Claims. (Cl. 103-161) The invention deals with a generator or pump with variable capacity, more specifically, intended to control hydraulic receptor units directly located in the wheels of an automobile vehicle.

There are known in the art pumps with variable capacity containing a star-arranged group of radial cylinders the pistons of which are controlled by a cam set in motion by a relative movement of rotation (rotary motion) with respect to the afore-mentioned group of cylinders.

In a first group of familiar pumps of that type, the cam is a peripheral fixed cam, with variable eccentricity, surrounding a rotatory group of cylinders arranged in a star-formation, the chambers of the cylinders being located on the side of the axis of rotation of the group of cylinders, in which case the yield, acceptable under normal operational conditions (of the order of 85 percent), becomes unacceptable when the delivery pressure reaches a high value, at the time of starting, for instance. At such a time, the delivery falls to values that may reach aslow as 40 percent as a result of the amount of the friction reached.

In a second group of known pumps of the type described above, the group of cylinders arranged in a star pattern is fixed, the chambers of the cylinders are lo- .cated towards their end furthest away from the axis of the pump, and a central cam that rotates about that axis sets in motion the pistons by means of oscillating mounted levers around the movable or shiftable axes with relation to a group of cylinders, which permits the course of the pistons to be varied. The levers in question are such that for each one of them the point where the cam acts on the lever and the point where the lever acts on the piston are located on the same side of the axis of oscillation of the lever under consideration. However, these pumps are heavy and bulky, the pull-back of their pistons in a centripedal direction requires springs, and zero capacity or delivery can be obtained only by such a set-up of the levers interposed between the cam and the pistons, which will permit the lateral action of the aforesaid pistons in their respective cylinders to always operate in the same direction during the course of delivery, which causes excessive wear and tear.

, The present invention has to do with pumps with variable capacity of the type referred to above, and one which consists of a rotative group, arranged in star-shape, of radially placed cylinders the chambers of which are located on the side of the axis of rotation and the pistons .of which are controlled by a fixed cam acting on the outer ends of the aforementioned pistons (those that are turned on the side opposite to the aforesaid axis of rotation); and the pump, in line with the invention, is characterized by the fact that the fixed cam is a central cam which, in order to control each piston, acts on one of the two arms of a trip-lever pivoting about an axis held in place on a frame participating in the rotatory movement of a group of cylinders, the second arm of the triplever acting on the outer end of the piston under consideration, with means being provided for the regulating of ice I the angular relation between the aforesaid turning frame and the aforesaid group of cylinders, in other words, to regulate the effective or active length of the aforesaid second arm, in order to modify the course of the piston, i.e., the delivery per turn of the pump.

In the drawings:

Figure 1 is a longitudinal axial section of the device.

Figure 2 is a cross-section taken upon the line II-II of Fig. 1.

Figure 3 is a cross-section taken upon the line IIIIII of Fig. l. Figure 4 is a cross-section taken upon the line IVIV of Fig. 1 which shows more in detail the device controlling the variation in the piston stroke.

Figure 4a is a diagram illustrating the operation of the device shown in Fig. 4; and

Figure 5 is a detailed sectional view illustrating specific features of the rocker construction.

The hydraulic generator illustrated in the drawings comprises six radially disposed cylinders, but it will be readily understood that this specific arrangement is not compulsory since the number and relative arrangement of the cylinders may differ from those illustrated without departing from the principles of the invention as set forth hereinabove and in the appended claims.

In Fig. 1 the driving shaft 1 rotates the flywheel 2 mounted in the conventional manner. A plate 3 is bolted at 4 on this flywheel and forms therewith a case revolving with the aforesaid shaft 1. A set of rockers 5 (six in the example illustrated and described herein) are spaced concentrically about the axis of rotation of the flywheel and pivoted on the latter, on the one hand, and on the plate 3, on the other hand, by means of pivot pins 6, 7 fitted in adequate bearings received in corresponding recesses. One arm 8 of each rocker 5 carries at its end a journal member 9 (see Fig. 5) on which a roller 10 is mounted, adequate bearing means 11 being interposed therebetween. This journal member 9 is displaceable in an elongated notch 12 formed in the plate 3. The roller 10 engages a cam member 13 hav ing a suitable contour which is secured by screws 15 on the outer case 14 of the generator. This cam member 13 is eccentric relative to the axis of rotation of the rockers 5 and carried by the plate 3 through the intermediary of a bearing 16. With this arrangement it is possible to avoid the only external reaction to a torque by avoiding the radial stress which would act in overhanging relationship on the flywheel and crankshaft assembly. The other arm 17 of these trip-levers bears a longitudinal bearing 18-19 for two wheels 20 and 21 trunuioned on the axis 22 of a piston 23, this bearingpathtaking the form of an arc turning its concave surface towards the axis of rotation of the group of cylinders. The radius of the rollers is equal to the distance separating the pivoting axis of each trip-lever and the zone of the path of the bearing in an arc-like direction, which is. in contact with the roller under consideration when the axis of the aforementioned roller is in the radial field or plane passing the axis of the corresponding trip-lever. These pistons 23 are slidably fitted in cylinders 24 bored in a spider-forming hub 25. This hub 25 is indirect contact with the flywheel 2 by being centered by the surface 26 thereof, and also with the plate 3 by engaging its surface 27. Thus, the hub 25 may be shifted angularly through a certain angle relative to the movable assembly comprising the flywheel 2, plate 3 and rocker 5. The cylinders 24 communicate through ducts 28 with a common cylindrical chamber divided into two compartments 30, 31 by a stationary distributor 29. The compartment 30 is used for drawing in the hydraulic fluid, and the other compartment 31 delivers the fluid to the members or apparatus to be actuated thereby. In thev circular cylindrical space 32 formed between the spiderforming hub 25 and the plate 3 a number of segments are disposed (six in the case contemplated herein). One half of the segments (see Fig. 4) is solid with the plate 3 and designated by the reference numeral 33, the other half being solid with the hub 25 and designated by the reference numeral 34. The fluid-filled gaps 35 and 36 constitute a hydraulic coupling between the hub 25 and the movable plate 3. Means are provided for example in the form of a reversing valve 37 (see Fig. 4a) for connecting the gaps 35 (connected to a common line 35a) with a high-pressure line 38, whereas the gaps 36 (connected to a common line 36a) communicate at the same time with a low-pressure line 39, both lines 38 and 39 being connected to a separate source of hydraulic power 40. As a result, a rotation of the spider-forming hub relative to the flywheel and plate assembly in the direction of the arrow F is obtained. If the reverse conditions prevail, that is, if the gaps are connected to the lines 39 and 3 8 respectively, the hub is shifted angularly in the opposite direction.

The operation of the hydraulic generator according to this invention is as follows:

Under normal operating conditions, which correspond substantially to the piston positions illustrated in Figs. 2 and 3, the spider-forming hub is so set relative to the movable rocker assembly that the rollers 20, 21 carried by the pins 22 of pistons 23 contact the extremities of cam'faces lfiand 19. Due to the rotational movement accomplished by the rocker assembly 5, the rollers. 10 engaging the stationary cam member 13' impart a slight oscillating motion to the rockers 5 about their pivot pins 6. This motion is transmitted through the arms 17 and rollers 24), 21 to the piston pins 22 so that a reciprocating movement is imparted to these pistons, the maximum amplitude of this movement being maximum in the case illustrated in Figs. 2 and 3. Therefore, in case of a relatively low delivery pressure the pistons 23 will suck in the maximum quantity of fluid when they communicate with the induction line 30 to force it into the line 31.

4 It is advantageous, to select angular values approximating those given hereinafter:

Dead centre l Beginning of piston stroke Acceleration period (conjugated with the deceleration period of another piston located 120' ahead of the former) 45 Piston moving at constant speed 75 Deceleration period (conjugated with the acceleration period of another piston located 120 behind the former) 45 Idle period between the end of the piston movement and the dead centre 7 30' Total 180 ders in their fluid-delivering phase, this number increas" ing to three during the junction periods, but the output is always uniform and without pulsation.

The servo-control system 41 (Fig. 4a) may also be used for driving the rotary distributor 29 which should generally have the same angular shift as the spiderforming hub if the fluid-distributing ports 28 do not ensure the proper distribution (as it generally occurs) with a 30-degree shift of the spider forming hub 25.

It will also be noted that though the invention is described herein as being applied to a hydraulic generator If the reaction torque, that is, the pressure obtaining in the delivery line 31, increases, a servo-controlsystem 4 1 (see Fig. 4a) operates the reversing valve 37 and brings about an angular shift between the spider-forming hub. 25 and the rocker assembly 5 by rnoving the segments. 33, 34 (Fig. 4). As a result, the rollers 20, 21 move along the cam faces 18, 19 and. the lever arm is reduced accordingly as well as the amplitude of oscillation of the pistons 23. This amplitude may even be cancelled completely when the axis of the piston-pin 2 2 and the axis of the pivot pins 6, 7 of rockers 5 are coincident.

The maximum angular shiftbetween the hub 25 and the series of pivoted rockers 5.is about 30 in the. example illustrated, but it may obviously be smaller or greater than this value. It will be noted that the cam faces 18, 19 constitute as many segments of a circle having its centre coincident with the axis of rotation of the flywheel 2 when the rocker 5 is in its intermediate position. As a result, the angle formed between the normal to the cam faces 18, 19 and the force exerted by these cam faces on the rollers 20, 21 is zero when the piston 23 is in its intermediate position. Consequently, any side reactions are reduced accordingly.

The contact between the rollers 10 and cam member 13, on the one hand, and between the rollers 20, 21 and cam faces 18, 19, on the other hand, is ensured bythe centrifugal force alone. The weightof the rockers and pistons, the distribution of this weight and the cam lift are calculated accordingly. 7

On the other hand, by adequately setting the cam member 13 the circulation of the fluid by gravity is facilitated by positioning the suction compartment 30 beneath the delivery compartment 31.

having a constant output per revolution, it is also applicable to a generator having a variable output per revolution; This advantageous feature results from the fact that the variation in the output obtains without changing the control device, as the cam movement is constantly the same and the variation in the piston stroke occurs subsequently by using a proportional system independent of the control hub.

It would not constitute a departure from the principle of this invention if the number of cylinders of the generator were changed, or if a cam member having a double symmetry giving two piston strokes per revolution were used, however these modifications may be contemplated only in those cases where the velocity of rotation is consistent therewith.

What I claim is: g

l. A variable output pump having a driving shaft and comprising a group of cylinders radially mounted to rotate with said shaft about a common axis of rotation, a piston slidably' mounted on each said cylinder, said piston having a roller mounted on its outer end, a stationary annular cam mounted with its center in eccentric relationship with the axis of rotation of said shaft and cylinders, a frame structure mounted on said shaft and around said cylinder group to rotate with said shaft and said cylinder group, a'rocker for each of said pistons, each said rocker pivoted on said frame structure adjacent each said piston, and each said rocker having two rocker arms oppositely disposed about said pivot, a roller mounted on the endof one of said rocker arms of each said rocker for engaging said stationary annular cam to oscillate said rocker about its pivot; a longitudinal bearing path comprising an inner surface of the periphery ofsaid other rocker arm, said bearing path for engaging the roller mounted on the outer end of said piston to oscillate. said piston in said cylinder, means. for

successively connectmg the interior axial end of each of said cylinders as they rotate to a hydraulic induction line as their associated pistons move outward in oscillation and to a hydraulic delivery line as said pistons move inward in oscillation, and means for angularly adjusting said frame structure with respect to said cylinders and pistons and thus for moving the engagement of said piston rollers with said longitudinal bearing paths toward or away from their respective said rocker pivots thereby providing for adjusting the effective length of said other rocker arm and extent of the oscillation of said pistons in said cylinders and therefore of the pump output.

2. A pump as described in claim 1 characterized in that said piston rollers are held in engagement with the longitudinal bearing paths, and the said rocker arm rollers are held in engagement with the stationary annular cam by centrifugal force generated in said movable pistons and rocker arms by their rotation with said drive shaft.

3. A variable output pump as set forth in claim 1, wherein each said bearing path has substantially the shape of an are having its concave side facing toward the common axis of rotation of said group of cylinders.

4. A variable output pump as set forth in claim 3, wherein each said bearing path is substantially the arc of a circle which is concentric with said common axis of retation when said rocker is at a midpoint of its oscillation.

5. A variable output pump as set forth in claim 3, wherein the radius of each of said piston rollers is substantially equal to the shortest distance between the axis of said rocker pivot and said bearing path.

References Cited in the file of this patent UNITED STATES PATENTS 1,081,810 Carey Dec. 16, 1913 1,346,548 Lamplough July 13, 1920 1,874,010 Hess Aug. 30, 1932 2,203,646 Aspden June 4, 1940 2,392,754 Mercier Jan. 8, 1946 2,474,536 Lundegard June 28, 1949 2,552,604 Thoma May 15, 1951 2,553,063 Simpson et al. May 15, 1951

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