US2017375A - Hydraulic change speed mechanism - Google Patents

Description

@t. 15, 1935. oam ETAL 2,017,375

HYDRAULIC CHANGE SPEED MECHANISM Filed Oct. 11, 1935 5 Sheets-Sheet 1 Wm R ff' ct. 15, 193.5. ROBIN r AL 2,017,375

HYDRAULIC CHANGE SPEED MECHANISM Filed Oct. 11, 1933 5 Sheets-Sheet 2 77 Van R Qct. 15, 1935.

LROBIN 5r AL HYDRAULIC CHANGE SPEED MECHANISM 5 Sheets-Sheet 3 Filed Oct. 11, 1935 Oct. 15, 1935. O A; 2,017,375

HYDRAULIC CHANGE SPEED MECHANISM Filed Oct. 11, 1933 5 Sheets-Sheet 4 L ROBIN ETAL HYDRAULIC CHANGE SPEED MECHANISM Filed OCT. 11 1933 Patented Oct. 15, 1935 PATENT OFFICE 2,017,375 HYDRAULIC CHANGE SPEED MECHANISM Leo Robin, Brussels, and Mathieu Van Roggcn,

Sprimont, Belgium Application October 11, 1933, Serial No. 6%,158 In Belgium October 14, 1932 6 Claims. (01. 60-52) The present invention relates to hydraulicchange speed mechanisms in which a pump driven by the engine delivers liquid into a receiver, and in which variations in speed of the driven shaft are obtained by variations in delivery of the pump.

The invention relates more particularly to mechanisms of this kind in which the operating means for the pistons of one group of cylinders of a cylinder block driven by a shaft, is adjustable in position in order to vary the stroke of said pistons, and the suction and the delivery passages for the cylinders of said groups communicate respectively with the delivery and the suction passages for the cylinders of the other group.

The object of the invention is to provide an improved hydraulic change speed mechanism in which motion is transmitted mechanically from 20 the primary or driving shaft to the secondary or driven shaft.

Another object of the invention is to reduce greatly the distance travelled by the liquid between the cylinders of one group and those of the other group.

A further object of the invention is to prevent damage to the mechanism which would be liable to occur if the delivery from one group of cylinders were not strictly constant, as it may sometimes happen.

A still further object of the invention is automatically to supply liquid in order to compensate any leakages which may occur.

Further objects and features of the invention will appear during the course of the following description with reference to the accompanying drawings which illustrate diagrammatically and simply by way of example, one embodiment 40 of the invention:

In these drawings:-

Figure l is a longitudinal section taken along the line I-I in Figures 4 to '7;

Figure 2 is a longitudinal section taken along 45 the line II-II in Figures 4 to '7;

Figure 3 is a longitudinal section taken along the line III-III in Figures 4 to '7;

Figure 4 is a cross section taken along the line IV-IV in Figures 1 to 3;

50 Figure 5 is a cross section taken along the line VV in Figures 1 to 3;

Figure 6 is a cross section taken alongthe line VI-VI in Figure 1;

Figure 7 is a cross section taken along the .55 line V1I-VII in Figures 1 to 3;

Figure 8 is a partial longitudinal section taken along the line VIII-VH1 in Figure 4.

In the various figures the same reference numerals refer to the same parts.

The hydraulic change speed mechanism ac- 5 cording to the invention comprises a first shaft 2 upon which is keyed a cylinder block 3, for example by means of a key 4 lodged in a groove 2a in the shaft 2. In this cylinder block 3 is formed a first group of cylinders 5 in which are 10 engaged pistons 6. The latter are connected by articulated rods 1 to a ring 8 mounted by means of ball bearings 9 upon a support l0 provided with trunnions Illa which can be pivoted in the crank case H and can be maintained in any desired position for example by turning a crank 56 (Figure 3) keyed upon a shaft 51 carrying a worm 58 engaging with a worm wheel 59 keyed upon one of the trunnions 1a..

In order to simplify the drawings, the pistons 6 and the rods 1 have not been shown in Figures 2 to 5 and '7.

The ring 8 carries two trunnions 8a which by means of ball bearings l2, for example, are engaged between the side plates I30. of a guide i3 rigid with a member l4, itself rigid with the cylinder block.

In the cylinder block 3 is provided a second group of cylinders 15 in which are engaged pis- "tons IS. The cylinders 15 are preferably arranged between the cylinders 5, so that the cylinders of the two groups alternate with each other. The pistons l6 are connected by articulated rods l1 to'a ring l8 mounted obliquely upon a second shaft I9 by means of ball bearings 20 mounted upon a support 2| keyed upon the shaft I9 by means of a key 22. In order to simplify the drawings, the pistons I6 and the rods I! have not been shown in Figures 1, 4, 5 and-6.

The ring l8 carries trunnions [8a which by 40 means of ball bearings 23 for example are engaged between the side plates 24a of a guide 24 rigid with a member 25, itself rigid with the cylinder block 3.

The cylinders of one group have their suction ducts in communication with the delivery ducts of the other'group and vice versa. This communication is obtained, according to the invention, along extremely short paths which lie entirely in the cylinder block. It is therefore not necessary to provide any fluid tight joint between the relatively moving parts. The ducts such as 26 which serve at one moment as inlet ducts and at another moment as delivery ducts for the cylinders [5 of one group can be put into communication with the ducts such as 21 which serve respectively as delivery ducts or inlet ducts for the cylinders of the other group, by means of distributing chambers such as 28 and 29 and distributing valves such as 30 for the cylinder group I5 and 3| for the cylinder group 5. The ducts 26 and 21 are formed in the cylinder block 3 by simple boring from the periphery of this block, the external wall of the cylinders being then closed for example by means of a screw-threaded plug such as 32.

The distributing valves 30 and 3|which are of the slide valve type are formed by cylindrical rods comprising an internal cavity 30a or 3 la and an aperture 30b or 3| b in their side wall. The cavity 30a or 3| (1 is easily formed by boring and the aperture 30?) or 3|b by milling. The distributing valves 30 and 3| are mounted respectively in bores 33 and 34 which can also be formed by boring parallel to the axis of the shaft 2 from the lateral faces of the cylinder block, one of the ends of the holes thus bored being then closed by a. screw-threaded plug such as 35.

The valves 30 and 3| are constantly urged out of their bore under the action of springs 36 of which Figures 1 to 3 show only the fork-shaped branches 360 which are cut at the same time as the heads of the valves 30 and 3|. The branches 36a are engaged in grooves in the form of flats rotation of the latter and consequently to keep the apertures 30b and 3 lb turned towards the distributing'chambers 28 and 29.

The springs 36 are made rigid with the cylinder block 3 by certain of the bolts such as 31 which will be mentioned hereinafter and which are'only illustrated in Figures 4 and 8.

The valves 30 and 3| which are urged out of their bores under the action of the springs 36 and the pressure of the liquid contained in the bores 33 and 34, bear upon plate 38 and 39 respectively.

The plate 38 is mounted obliquely with respect to the shaft H! which carries it by means of a ball bearing 40.

The plate 39 is mounted obliquely with respect provided in the valve heads so as to prevent the to a fixed sleeve 4| by means of a ball bearing 42. The fixed sleeve 4| is concentric with'the shaft 2 and also serves as a bearing for it. The plate 39 is thus mounted obliquely with respect to the shaft 2 about which it is mounted.

In the case when the axes of the cylinders 5 V and of the corresponding. valves 3| lie upon the same radius, the inclination of the plate 39 with respect to the ring 8 must be made such that the straight line which lies in the plane of the operative face of the plate 39 and is perpendicular to the axis of the shaft 2 will also be perpendicular to the straight line which lies in the plane of the ring 8 and is perpendicular to the same axis.

Similarly, if the axes of the cylinders l5 and the corresponding valves are situated upon the same radius, the inclination of the plate 38 with respect to the inclination of the ring l8 must be made such that the straight line lying in the I plane of the operative face of the plate 38 and perpendicular to the axis of the shaft 9 will also be perpendicular to the straight line lying in the plane of the ring l8 and perpendicular to the same axis.

If the axes of the cylinders and of the corresponding valves are situated upon radii which make a certain angle with each other, for example 20, the straight line which lies in the plane of the operative face of the plate 39 or of tfie plate 38 and is perpendicular to the axis of 't e respective shaft 2 or IE, must make the same .angle and in the same direction with the straight the respective shaft 2 or |9. The amount of inclination of the plates 38 and 39 is such that it produces a sufficient displacement of the valves to ensure the distribution.

The distributing chambers 28 and 29 are formed partly by circular grooves formed in the cylinder block 3, so that they each communicate with the bores 33,- and 34, and partly by rings 43 and 44 engaged upon the first shaft 2. These rings comprise an internal groove 43a or 44a communicating with the exterior of the corresponding ring through holes 43b or 44b. The grooves 43a or 44a communicate with an internal cavity or bore 21) formed in the shaft 2, through passages 2d or 2 each provided with a non-return valve formed by a ball 45 mounted in a flared part of this passage. The bore 219 communicates through a passage 2g with a groove 4| a formed in the sleeve 4|. This groove is supplied with oil through a duct 4| b (Figure 2) connected to an oil pump such as a gear pump 60.

The delivery ducts of the cylinders of each group are connected by means of the distributing chambers 28 or 29 to one or more variable volume chambers each connected to these distributing chambers. The distributing chamber 29 is for example connectedto chambers such as 43 (Fig ure 8) by ducts such as 41. Each chamber 46 is formed by a cylinder 48 bored in block 3 in which moves a piston 49 constantly urged by a spring 50 to occupy a position such that the volume of the chamber 46 will be a minimum. This minimum volume is obtained when the restricted part 4911 of the said piston is at the end of a notch 5|a of slightly larger cross section than that of the said restricted part, this notch being formed in the wall 5| of the chamber towards which the said piston is constantly urged. The wall 5| is held in place by certain of the bolts 31 which have been mentioned above and which also serve to secure the member 25 rigidly to the cylinder block 3.

The spring 50 is of such a strength that during the normal operation of the. mechanism, the chamber 46 is kept at its minimum volume but yields under the action of an excess pressure of the liquid employed. An aperture 48a in the wall of the cylinder 48 is adapted to put the interior of the chamber 46 in communication with the atmosphere when'the piston 49 uncovers it as the result of an excess pressure determined by the strength of the spring 50.

The ducts 41 are formed by holes bored obliquely with respect to the cylinder 48, so that the section 41a on one side of the cylinder 48 will be on one side of the fluid-tight joint 6| and the section 41b will be on the other side of this joint. 60

on to the surface by means of which the said. small endbears upon the piston Hi and at the other end on to the bearing surface l'|,f of the foot or big end Hg of the connecting rod. The pistons 6 and the rods 1 are formed in the same manner as the pistons I6 and the connecting rods As already mentioned above, the shaft 2 is supported by the fixed sleeve 4| which acts as bearing for it and is mounted in the casing II. The shaft I9 is engaged in the cylinder block 3, rigid with the shaft 2, by means of a ball bearing 52. The member 25 rigid with the cylinder block 3 is rigid with a member 53 (Figure 1) mounted in the casing I I by means of a ball bearing 54. This member 53 also supports the shaft l9 by means of a ball bearing 55.

Let us assume the shaft 2 to be the driving shaft, the shaft I9 to be the driven shaft and the cylinders 5 and I5, their inlet and delivery ducts, the bores for the distributing valves, the distribution chambers and the variable volume chambers, to be filled with a liquid such as oil.

Let us also assume the ring 8 to be identical with the ring I8 and inclined so as to be paralled to the latter.

The rotation of the cylinder block 3 and of the rings 8 and I8 produces equal displacements of the pistonsfi and I6. As the cylinders 5 and I5 are equal and are situated at the same distance from the axis of the shaft 2, and as the distributing valves are arranged in such a way that the delivery of the cylinders of one group corresponds to the inlet of the cylinders of the other group,-the rotation of the shaft 2 has only the effect of making the liquid circulate from one group to the other. The driven or resisting shaft I9 therefore remains stationary.

Let us now assume that the ring 8 is perpendicular to the axis of rotation of the shaft 2.

Upon the rotation of the shaft 2, the pistons 6 not only are not urged to move in the cylinders 5, but cannot move with respect to them. The.

pistons I5 on the other hand are urged to move with respect to the cylinders I6, but as they cannot deliver liquid into the cylinders 5, they also remain stationary in their cylinders. At the same time the reaction they exert upon the ring I8 by means of the rods IIa has the effect of locking the ring I8 completely with respect to the driven shaft I9. As the ring I8 is driven at the speed of the driving shaft by the trunnions I8a, the driven shaft is thus compelled to turn at the speed of the driving shaft under the effect of a torque equal to the driving torque. There is no circulation of the liquid in this case. The movement is. thus transmitted by a direct drive.

Let us assume that, instead of placing the ring 8 perpendicular to the axis of the shaft 2, it is slightly inclined with respect to this position and in the same direction as the ring I8.

Let us assume for example that this inclination is such that the sine of the angle of inclination is equal to one tenth of the sine of the angle of inclination of the ring I8 with respect to the plane perpendicular to the axis of the shaft 2.

When the shaft 2 rotates, the pistons 6 move slightly in the cylinders 5. They deliver and draw in only one tenth of the volume of charge which the pistons I6 would supply if they were free to move in their cylinders. The possible relative movement between the shafts 2 and I9 is thus only one tenth'of the speed of the driving shaft 2. The driven shaft I9 therefore turns at a speed equal to the speed of the driving -shaft, less one tenth of this speed, that is to say, at a speed equal to nine torque transmitted to the driven shaft increases with this increase'in pressure. It is to be noted that under these conditions the amount of liquid in circulation is only one tenth of the amount in circulation when the two rings are parallel. 5

Let us assume that the inclination of the ring 8 is increased in order to make it approach that of the .ring I8.

The speed of the driven shaft falls in proportion to the difference between the sines of the angles of inclination while the pressure of the liquid between the pistons and consequently the driving torque exerted upon the driven shaft increases in inverse proportion to the speed.

Let us now assume that the ring 8 is placed in 15 a more inclined position than the ring I8 with re- S-pect to the plane perpendicular to the axis of the shaft 2.

Let us assume for example that the sine of the angle of inclination of the ring 8 is one fifth 20 greater than the sine of the angle of inclination of the ring I8.

Under these conditions, as the pistons 6 make a stroke which is one fifth greater than the stroke of the pistons I6, they draw in and deliver more 25 liquid than the pistons I6 are able' to do and the difference must be compensated by an absolute movement of the shaft I9 in the opposite direction to the shaft 2 at a speed equal to one fifth of the speed of the shaft 2. The relative speed of these 30 shafts is thus six fifths of the absolute speed of the shaft 2. The driving torque exerted upon the driven shaft is equal to five times the driving torque exerted by the driving shaft.

group of cylinders 5 will correspond respectively with the delivery and suction of the group of cylinders I5. Consequently, the driven shaft I9 is compelled to turn at a higher speed than the 45 driving shaft 2. For an inclination of the ring 8 such that the sine of the angle of inclination will be equal to less than one fifth of the sine of the angle of inclination of the ring I8, the speed of the shaft I9 is equal to six fifths of the speed of 50 the shaft 2. The driving torque exerted upon the shaft I9 is equal to five sixths of the driving torque exerted by the shaft 2.

The driving shaft may also be formed by the shaft I9 and the driven shaft by the shaft 2.

- The mechanismwill be employed under these conditions when it is desired to use the engine as a brake. Let us assume that the ring 8 is perpendicular to the axis of rotation of the shaft 2 and that the shaft I9 has a tendency to turn faster 60 than the shaft 2. Any relative rotation of the shaft I9 will produce a movement of oscillation of the plane of the ring I8 about an axis perpendicular to the plane passing through the axis of the. shaft I9 and through the axis of the trunnions I8a. This movement of oscillation will have the effect of displacing the pistons I6 in the cylinders I5. But as the pistons 6 are locked in the cylinders 5 on account of the fact that the ring 8 is locked in the position indicated above, this movement of the pistons I5 is impossible. Consequently, the rotation of the shaft I9 has the effect of driving the member 25 at a like speed by means of the ring I8, the trunnions I81: and theball bearings 23.

During the operation of the mechanism the liquid under pressure in the cylinders engages in the passages such as Ilia and will filter between the bearing surfaces of the corresponding piston and connecting rod head engaged therein. Consequently, the presence of a film of liquid between these two surfaces is ensured, whereby friction will be considerably reduced, as is known.

The liquid under pressure also enters the ducts 4 such as llb and filters between the bearing surfaces of the connecting rod big ends and the corresponding rings.

If leakages of liquid occur, reduced pressures will be produced in the distributing chambers.

These reductions in pressure will cause the balls 45 to lift from their seats and allow .the entry of oil maintained under pressure in the bore 2b by the pump 60 connected to the duct Mb. The

pressure supply indicated above also has the advantage of providing the lubrication between the shaft 2 and the sleeve 4| which serves as its bearing.

If for any reason an excessive pressure is produced in one or the other of the distributing chambers, this pressure will have the effect of pushing the piston 49 against the resistance of the spring 5-3. If the pressure is sufficient the piston 49 will even uncover the aperture 48a and 4.0 permit a certain quantity of oil to escape, after which the aperture will immediately be closed again on account of the sudden fall in pressure of the oil. It may happen that if the escape of oil is too great, it will be followed immediately by suction effected by the lifting of the valves 45.

In the foregoing description, it has been assumed that the cylinders of the two groups have the same diameter and that the bores for the big ends of all the connecting rods are at the same 50 distance from the axis of the rings which control the displacements of these rods; that is to say, it has been assumed that for one and the same inclination of the rings the volumetric capacities of the cylinders of each group are the same.

If the diameters of the cylinders are made different in each group and/or if the supports for the big ends or feet of the connecting rods are at different distances from the axis of the' corresponding rings, a direct drive will always be obtained when the ring 8 is perpendicular to the axis of the shaft 2; but the other speeds will be equal in each case for inclinations of this ring which are different in each case and such that the ratio of the cylinder volumes in one case are the sameas the ratio of the cylinder volumes in the other case. In other words, the speed ratio is not a function of the relative inclination of the rings,

' but simply of the relative value of the cylinder 7 volumes.

It is obvious that the invention is not exclusively limited to the formof construction illustrated and that many modifications may be made in the form, arrangement and construc- 76 tion of the parts employed in its construction,

without on that account going outside the scope of the present invention.

Thus, for example, it is not necessary for the cylinders to be arranged parallel to the axis of the shafts 2 and I9, nor for the reciprocating ,5

motion of the pistons to be produced by rings which are inclined with respect to the axis of the said shafts. In particular the cylinders may be arranged in a star formatioin and the pistons of these cylinders may be driven by a device 10 formed by a bearing mounted upon a. crank pin. In this case the eccentricity of the crank pin driving the pistons of one group will be constant while the eccentricity of the crank pin operating the pistons of the cylinders of the other group 15 will be variable. It is to be understood that while the term hydraulic has been used in this specification, any other suitable liquid may be used.

What we claim is: 20.

1. A hydraulic change speed mechanism comprising a primary shaft, a secondary shaft and two groups of cylinders both formed in a single cylinder block with slide valves situated in bores therein, said block being operatively connected 25 to and rotatable with said primary shaft, pistons movable in said cylinders and rods on said pistons, and ducts connecting said groups of cylinders together whereby the suction and delivery of the cylinders of one group form respectively 30. the delivery and suction of the cylinders of theother group, operating means connected to the piston rods of one group, said means being adjustable for varying the stroke of said pistons and comprising a primary ring operatively con- 5 nected to said primary shaft, and operating means connected to the piston rods of the other group and comprising a device keyed on said secondary shaft and a loosely rotatable ring mounted on said device and operatively con- 40 nected to the primary shaft and to the piston rods of said other group.

2. A hydraulic change speed mechanism as claimed in claim 1 further comprising two distributing chambers in the said cylinder block, 45

the bores for the valves being connected by ducts with said distributing chambers, each of said valves controlling the passage of liquid between the corresponding cylinder and either one or the other of the distributing chambers, each of these 0 chambers being connected by means of the said valves to the cylinders of one group in which a suction stroke occurs and at the same time to the cylinders of the other group in which a delivery stroke occurs. 55 3. A hydraulic change speed mechanism as claimed in claim 1 further comprising two dis- 7 tributing chambers in the said cylinder block, the

bores for the valves being connected by ducts with said distributing chambers, each of said 60 valves controlling the passage of liquid between the corresponding cylinder and either one or the other of the distributing chambers, each of these chambers being connected by means of the said valves to the cylinders of one group in -which a suction stroke occurs and at the same time to the cylinders of the other group in which a delivery stroke occurs, and in which each slide valve comprises a cavity in the wall of which is formed an aperture adapted to put this cavity in communication with one of the distributing chambers, the saidcavity also communicating with the part of the bore' of the slide valve which is in conmiunication wit the corresponding cylinder.

4. A hydraulic change speed mechanism according to claim 1, characterized by the feature that the valves are urged by springs, plates being provided against which the valves contact, said plates being inclined with respect to the ring which controls the displacements oi the pistons moving in the corresponding cylinders.

' 5. A hydraulic change speed according to claim 1, in which the ducts serving for the flow of the liquid between the cylinders are in communication with a variable volume chamber provided in the cylinder block, the movable wall of which tends under the action of a spring to keep this chamber at its minimum volume.

6. A hydraulic change speed mechanism according to claim 1, in which the ducts servin tor the flow of the liquid between the cylinders are in communication with a variable volume chamber provided in the cylinder block, the movable wall of which tends under the action of a spring to keep this chamber at its minimum volme, an outlet duct on the said block providing a connection between the chamber and the atmosphere while the said outlet duct is adapted to be 10

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