Piston and barrel machine with fixed centering toggle type joint

Rotary piston and barrel machine comprising a thrust plate inclined in relation to its geometrical spin axis which coicides with the geometrical axis of the barrel, the central part of the inclined plate comprising a spherical bearing which revolves freely around a fixed central toggle type joint anchored to the central part of the barrel, whereas the barrel is connected to a rigid peripheral housing, the central toggle type joint being integral with a rigid half shaft connected to the rear part of the housing, characterized by at least one rod connected rigidly to the toggle type joint, as well as to a piston disposed inside a bore of the barrel and subjected to the action of an under-pressure fluid so that at least one part of the axial stresses applied to the toggle type joint is transmitted to the barrel without being applied to the housing.

BACKGROUND OF THE INVENTION 
This invention relates to a piston and barrel rotary machine for pumps, 
hydraulic motors or compressors. 
The invention concerns at type of machine covered by the French patent 
application No. 85 15604 filed by the Applicant, the piston and barrel 
rotary machine comprising a thrust plate inclined in relation to its 
geometric rotation axis which coincides with the geometrical axis of the 
barrel, the central part of the inclined thrust plate comprising a 
spherical bearing which rotates freely around a fixed central toggle type 
joint rigidly connected to a rigid half shaft anchored directly into the 
central part of the barrel whilst the said barrel is connected by a rigid 
peripheral housing which covers the rear of a linkage assembly behind 
which it closes, and in this machine the central spherical toggle type 
joint is rigidly connected to a second rigid half shaft situated opposite 
the first one with which it is aligned, this second half shaft, via its 
opposed end, being rigidly anchored onto the rear part of the machine 
housing. 
First of all, the invention seeks to transfer the various forces and 
stresses to which the toggle type joint is subjected on the barrel of the 
machine; it has actually been established that the barrel constitutes an 
extremely rigid unit, in opposition to the housing in which the thrust 
plate, and the movement transmitter are housed. 
According to the invention, a new disposition is provided in which the 
housing is now only subjected to small stresses, which makes it possible 
to manufacture it as a lighter structure as before. 
Moreover, the invention also automatically compensates the differential 
expansions which may occur when the machine is operating. 
In addition, the invention also makes it possible, by submitting the thrust 
plate to a prestressing, to compensate the stresses exerted on it during 
operation. 
Compensation of stresses to make the thrust plate practically floating in 
relation to the toggle type joint which carries it may only be exerted 
when the machine is operating so that the machine parts are not subjected 
to significant static loads when the machine is not operating. 
SUMMARY OF THE INVENTION 
In accordance with the invention, the piston and barrel rotary machine, 
comprising a thrust plate inclined in relation to its geometrical rotation 
axis which coincides with the geometrical axis of the barrel, the central 
part of the inclined thrust plate comprising a spherical bearing which 
rotates freely around a fixed central toggle type joint anchored to the 
central part of the barrel whilst the barrel is connected to a rigid 
peripheral housing, the central toggle type joint being integral with a 
rigid half shaft connected to the rear part of the housing, at least one 
rod being rigidly connected to the toggle type joint as well as a piston 
disposed inside a bore of the barrel and subjected to action of a 
pressurized fluid so that at least one part of the axial stresses applied 
to the toggle type joint is transmitted to the barrel without being 
applied to the housing. 
Various other features of the invention also appear from reading the 
following detailed description. 
By way of examples, in no way restrictive, forms for embodying the subject 
of the invention are shown on the annexed drawings.

DETAILED DESCRIPTION OF THE INVENTION 
The machine shown according to the embodimentn of fig. 1 comprises a 
housing 1 connected to the peripheral part of a barrel 2 to which the rods 
3 are secured, the tie rods 3 forming in the same time braces and being 
used to secure and support a body 4 delimiting cylinders 6 in which 
pistons 7 are provided to slide. The body 4 constitutes either a pump body 
or a motor body depending on whether the cylinders 6 are used to deliver a 
fluid or admit a fluid intended to drive the pistons 7. 
In the type of machine the invention relates to, the body 4 is well-known, 
as well as the layout of the pistons 7 in the cylinders 6 and accordingly, 
this part of the machine is not described further. 
The barrel 2 delimits sleeves 8, one of which is shown, and in each of the 
sleeves 8, it is possible to move a slide block 9 connected by a rod 10 to 
one of the pistons 7. 
The slide block 9 contains bearings 11 for a spherical head 12 of a 
cylindrical connector rod whose foot 13 is also cylindrical and is 
pivotally mounted in one of a plurality of bearings 14 contained by an 
oscillating thrust plate 15. 
The thrust plate 15 is carried by a toggle type joint 16 to which it is 
connected by hemispherical rings 17 forming a spherical bearing. The 
thrust plate 15 is prevented from freely rotating by a reaction connecting 
rod 18 pivotally mounted by its spherical head 19 in a footstep bearing 20 
rigidly connected by a frame 21 which itself is connected both to the 
housing 1 and the barrel 2 by means of gussets 22. 
The frame 21 forms a bearing support 23, for a primary shaft 24 provided 
with a pinion 25. 
The primary shaft 24 is a also carried inside a bearing 26 connected to the 
rear part 1a of the housing 1. The rear part 1a referred to above is 
itself reinforced by a plate 27 able to form a thrust plate and which 
cooperates with the rear part 1a for supporting a thrust bearing 28 of a 
movement transmitter 29 constituted in the form of a bevelled disk 
comprising an annular gear 30 gearing with the pinion 25. The movement 
transmitter 29 carries a thrust bearing 31 connected to the oscillating 
thrust plate 15. 
The movement transmitter 29 is carried by bearings 32 whose inner cage is 
attached to a half shaft made up of a tubular tail 33 rigidly connected to 
the toggle type joint 16, the tubular tail 33 being able, if required, to 
form a single part with the said toggle type joint 16. 
The tubular tail 33 is coaxial with the geometrical axis of the barrel 2 
and is inserted in an opening 34 of the plate 27. 
A stop ring 35 is mounted, preferably being adjustable, on the extremity of 
the tubular tail 33 so as to take support, preferably via resilient means, 
for example a conical spring washer 36, against the plate 27. 
It is an advantage, as shown in the drawing, that a preloading shim 27a is 
inserted between the plate 27 and the rear plate 1a of the housing. The 
thickness of the shim 27a is calculated so that adjustment of the 
respective values of the preload forces represented at L.sub.1 and L.sub.2 
will be according to the desired distribution ratio. For example, it is 
possible to select that L.sub.1 =L.sub.2 =L/2. 
In order to prevent that the toggle type joint 16 and tubular tail 33 from 
rotating, the part of the toggle type joint 16 turned to the barrel 2 is 
connected to the barrel 2 by means of a key 37. 
The toggle type joint 16 is also carried by the threaded part of a rod 38 
concentric to the tubular tail 33. 
The rod 38 forms a a larger diameter part 38a guided into a bore 39 of the 
barrel 2 to which it is seal-connected by gathers 40. The rod 38 forms a 
smaller diameter part 38b which extends inside the tubular tail 33 and, 
along with the tubular tail 33, delimits an annular chamber 41. 
The smaller diameter part 38b of the rod 38 is seal-connected to the 
tubular tail 33 by means of a sealing gasket 42 and is also connected 
mechanically to the tubular tail 33 by means of a stop counternut 43 which 
takes support on the free extremity of the tubular tail 33. The counternut 
43 thus provides for blocking at the desired adjustment of the position of 
the rod 38 inside the toggle type joint 16 so as to leave a clearance 16a 
inside the housing on the barrel 2 of the front cylindrical part of the 
toggle type joint 16. 
A channel 44 enables the above described annular chamber 41 to be connected 
to an pressurized fluid source (not shown), especially oil source, so that 
this oil is conveyed by the annular chamber 41 to distribution channels 45 
provided inside the toggle type joint 16 and enabling the oil to be 
directed to the bearing forming hemispherical rings 17. 
The larger diameter part 38a of the rod 38 is rigidly connected to a piston 
46 disposed inside a cylinder 47 of the barrel 2. The rest face of the 
piston 46, along with the cylinder 48, delimits a chamber 48 for the 
admission of a pressurized adjustment fluid, especially oil derived from 
an adjustable source 49 connected to the body 4. 
The source 49 may be constituted by a compressor or regulator applying in 
the chamber 48 a calibration pressure able, for example, to depend on the 
working pressure prevailing inside the body 4. 
The unit formed by the barrel 2, tie rod 3 and body 4 constitutes an 
extremely rigid unit so that the pressure developed inside the chamber 48 
may be a pressure sufficiently high to compensate at least one part of the 
oppposing forces applied to the toggle type joint 16 by the oscillating 
thrust plate 15 when the machine is operating. 
The pressure in the chamber 48 exerted on the piston 46 is transmitted by 
the various parts of the rod 38 to the toggle type joint 16 and to the 
stop counter nut 43 bearing against the tubular tail 33, and the stop ring 
35 can apply part of the tresses to the plate 27 supporting the bearing 
28, without these forces being applied to the housing 1. 
As a result of the foregoing disclosure, the clearance 16a provided inside 
the housing or the barrel 2 of the front cylindrical part of the toggle 
type joint 16 is in fact intended to control the travel of the piston 46 
whose role is to pull the toggle type joint 16 so as to apply to it a part 
of the stresses during pumping with a view to relieve the thrust bearings 
28 and 31. 
By correctly selecting the pressure in the chamber 48, if desired, it is 
possible to ensure that all the stresses exerted axially on the toggle 
type joint 16 are transmitted by the tubular tail 33 without being 
transmitted to the housing 1 which may then be made of a specially light 
structure. 
Given that the axial stresses are applied to the fluid mattress or cushion 
constituted in the chamber 48, the chamber 48 also acts as a compensator 
of the differential expansion able to exist between the tubular tail 33, 
the various parts of the rod 38 and the body of the barrel 2. 
FIG. 2 illustrates a simplified variant according to which the same 
reference numbers denote the same devices as shown in FIG. 1. 
According to FIG. 2, the toggle type joint 16 is directly secured to the 
threaded part of a rod 38.sub.1 itself connected to a piston 46.sub.1 
delimiting, along with a cylinder 47.sub.1 of the barrel 2, a chamber 
48.sub.1 so as to develop a compensation pressure. 
Moreover, a hydraulic cylinder 50 is provided inside the plate 27 
reinforcing the rear part 1a of the housing 1, the hydraulic cylinder 50 
acting on the bearing 28 against which abuts the movement transmitter 29. 
The hydraulic cylinder 50 may consist, as shown diagrammatically, of an 
ordinary annular gasket. 
The above-mentioned disposition, resulting from the preceding explanations 
and the drawing, allows for a distribution of the hydraulic pressures 
intended to balance the axial stresses, namely firstly on the barrel 2 and 
secondly on the plate 27. The pressure able to be exerted by the hydraulic 
cylinder 50 is applied to the movement transmitter 29 and by the thrust 
bearing 31 to the oscillating thrust plate 15, which makes it possible to 
reduce and virtually annul in certain operating conditions the axial loads 
between the toggle type joint 16 and the hemispherical rings 17 of the 
oscillating thrust plate 15. 
FIG. 2 shows that the hydraulic cylinder 50 is connected via a duct 51 to a 
pressure regulator 52 which may be piloted by any suitable device, such as 
a computer for varying the compensation pressures exerted by the hydraulic 
cylinder 50 and the piston 46.sub.1 depending on the cyclic pressure 
variations exerted by the thrust plate 15 on the toggle type joint 16. 
The use of the shim 27a in the embodiment of FIG. 2 provides additional 
safety in the event of failure of hydraulic compensation. 
The invention is by no means restricted to the detailed illustrated 
examples of embodiment, a number of modifications being possible without 
departing from the context of the invention as shown in the appendent 
claims.