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Патент USA US3075482

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Jan. 29, 1963
vFiled March 5', 195s
5 Sheets-Sheet 1
_ @4h/@M
Jan. 29, 1963
Filed March 5, 1958
3 Sheets-Sheet 2
Jan. 29, 1963
Filed March 5, 1958
5 Sheets-Sheet 5
ßy my
'u Í jím
Patented Jan. 29, 1963
piece with the latter. In a modification, this abutment
means is constituted by a balancing piston disposed in
Georges Garnier, Asnieres, France., assigner to Air
Equipernent, Asnieres, France, a French company
Filed Mar. 5, 1958, Ser. No. 739,329
Claims priority, application France Mar. 8, 1957
5 Claims.
(Cl. 103-162)
a bore in the housing and constantly applied against the
rear face of the cam by the delivery pressure in a re
gion denn-ed in suit-able manner -for substantially balanc
ing the thrust exerted on the cam by the pump pistons.
Owing to this fixed abutment member, or to this bal
ancing piston, the pivot pin merely maintains the cam
in position and is subjected to but a small force.
The object of the present invention is to provide im 10 In another improvement, the plate which applies the
piston shoes against Ithe forward face of the cam is posi
provements in variable-How pumps of the drum piston
tively driven in rotation by the rotor so as notably to
type i.e. having pistons sliding in bores provided in a
reduce friction. This drive could be obtained, on the
drum, or rotor, pumps in which the stroke of the pistons
one hand, by providing a suitable connecting means, for
in the rotor depends on the position of a cam or swash
plate tiltable »about an axis orthogonal to the axis of the 15 example of universal joint type, between the support
plate for the shoes and the «sliding return member which
is axially disposed in the rotor Iand is subjected to` the
One of these improvements concerns the manner of
action of Ia spring and, on the other hand, by positively
mounting the rotor. It is known that, to obtain correct
driving this Iaxial return member through the medium
pump operation, it is essential that the rotor remains
applied constantly against the distribution surface, the 20
of the roto-r.
In a particular embodiment of this connectingy means,
the latter is formed by a thin member comprising two
tribution 'surface creating considerable leakage.
lugs disposed in a recess in the support plate for the
It has been discovered that, to satisfy this condition,
shoes and two lugs disposed in a recess disposed in the
the rotor must be carried by at least one main bearing
disposed in a Well-defined region in the vicinity of the 25 axial return member orthogonal to the other recess.
The positive driving in rotation of the return mem
pivot axis of the cam, and that, if other’ bearings are
ber may be ensured by la lug forming akey or by a slid
provided outside «said region, these bearings must have
ing yconnecting between the return member and the end
greater play than that of the main bearing or bearings.
of the shaft journalled in the auxiliary bearing of the
The region in >which the main bearing or bearings are
located is determined mathematically by the condition 30 pump body, which has, for example, hat-faced portion
and is slidably mounted in an aperture having a corre
that the resultant of the forces exerted on the rotor, apart
spending shape formed in an axial extension o-f the return
for the reaction of the distribution surface be directed
toward said distribution surface and fall within the sur
Another improvement relates to the piston shoes.
face of contact of the rotor and the said distribution
The spherical head of the piston is generally set in the
shoe »and the latter bears on the cam by a hat part. It
In a particular embodiment, the rotor is carried by a
is very advantageous to reduce the coefficient of fric
shaft which extends therethrough and is rigidly fixed
slightest gap or separation between the rotor and dis
tion ot the shoe on the cam so as to improve the eñiciency
to the housing, the bearing, or bearings, being disposed
land prolong the life of the pump.
in the aforementioned region.
For this pur-pose, it has already been proposed notably
This arrangement is advantageous in that the pres 40
ence of »the cam plate, the piston shoes yand the support
plate, makes it practically impossible to provide a bear
ing outside the rotor in the deñned region mentioned
This arrangement also enables the rotor to be driven 45
by a ring gear machined directly on the rotor and mesh
to mak-e the cam plate of graphite or to provide elec
trolytically a deposit or layer of metal on the shoe hav
ing a -goo-d coefficient of friction (cadmium, indium or
silver, for example). But these solutions have disad
vantages. In the first case, lthe graphite cannot support
high mechanical stresses and the cam plate of lgraphite
must incorporate a rigid reinforcement, for example of
steel. The result is a rather space-consuming structure
which is heterogeneous and might be rather fragile. In
the second case, the electrolytic coatings on the shoe are
thin and it is ditiicult to be sure of their adherence, and
numerous diñîculties have arisen due to irregular de
ing wit-h a gear rigid with the driving shadtof the pump,
since only the arrangement of a central shaft permits
providing a rotor bearing in a plane perpendicular to
the rotor axis and containing said ring gear.
In this case, the invention also provides «an arrange
ment whereby the meshing of the rotor ring gear is such
posits which ñake oiî.
that the delivery passageway of the pump is located in
According to the invention, the shoes are provided With
the plane of the meshing and on the side of the axis of 55
an element comprising at least one ñat face and composed
the rotor opposed to that of said meshing.
of a metal having a good coetîicient of friction, for ex
According to another improvement to the centering
of the pump> body or rotor in the housing, there is pro
vided, in addition to a main bearing on the pump body
ample silver, this elernent being disposed in the shoe in
such manner that the flat face protrudes from the shoe and
itself, a second bearing carried by the housing and in 60 ensures that the shoe bears against the cam plate only
through the medium of this ñat face. This element could
which is journalled the cylindrical end of a shaft ñtted
be set in the shoe or could be simply maintained in posi
in the pump body, for example by a conical portion,
tion by the force exerted by the piston yon the cam.
and lixed in position by a nut.
In a particular embodiment ot said element, the latter
Another improvement is in the pivotal mounting of
is in the form oi a thin plate lodged in a shallow recess
the tiltable cam or swash plate and provides, in addi
65 in the shoe.
_ `
tion to the usual pivot pin, abutment means which ex
erts on the cam an action balancing the thrust exerted
on the cam by the pump pistons, this abutment means
being in contact with the cam through the medium of a
part-cylindrical face, the axis of the cylinder coinciding
In another embodiment, said element protrudes from the
shoe not only on the side adjacent the cam but also on
the side adjacent the head of the piston and they recess
formed in the shoe is such that the spherical head of the
70 piston is retained merely by the edges of the shoe and
with the pivot axis of the cam.
bears against the inner protruding face of said sliding ele
in one embodiment, this abutment means is constituted
by lìxed parts rigid with the housing or machined in one
under the `effect of the delivery pressure of the pump pre
vailing in the chamber 22 at the rear of the piston. The
It can 'be seen that after Wear of the sliding plate or
element of the invention, it is easily changed by dis
mantling the pump, whereas wear of the electrolytic de
forward face of the piston `and the corresponding part
24 of the cam have a part-cylindrical shape, the axis of the
posits would require changing the entire shoe, that is,
cylinder coinciding with the axis of the pivot pin 20
would require detaching the spherical end of the piston.
thereby permitting tilting of the cam.
Further features and advantages of the invention will
By means of this arrangement, the cam 15 is constantly
be apparent from the ensuing description, with reference
balanced by the action of the piston 23 whose position is
to the accompanying drawings, of variable-flow drum
precisely .determined so that its thrust balances substan
piston pumps` incorporating the improvements of the in
10 tially the resultant of the thrusts exerted on the cam by
the pump pistons. The inclination or tilt of the cam is
In the drawings:
controlled by a small piston 25 actuated hydraulically
FIG. 1 is an axial sectional view of a pump having two
and the return of the cam is ensured by the action of a
outer bearings;
piston 26 the rear of which is continuously subjected to
FIG. 2 is a view partily in »section and partly in plan
View taken along line II-I'I of FIG. 1;
15 Lthe delivery pressure.
In order to reduce friction, the support plate 1S of the
‘ FIG. 3 is a sectional View taken along line III-_III of
shoes 17 of the pistons 16 is driven positively in rotation
FIG. 1;
~by means of a .universal joint formed by a thin member
F‘IG. 4 is an axial sectional `'view of a modification of a
27 carrying upstanding lugs. Two of these lugs 28 are
detail of the pump shown in FIG. 1;
20 disposed in a slot 29 in the plate 18 and two other lugs
FIG. 5 is a partial axial sectional view of a modifica
tion of the pump shown in FIGS. l to 3 in which the
balancing piston of the cam is replaced by a fixed abut
ment member rigid with the »housing of the pump;
FIG. 6 Yis a sectional view taken along line VI'-VI of
FIG. 5;
are .disposed in a groove 3,0 orthogonal to the slot 29 and
_provided Vin a slide member 31 which is slidable in an
axial bore 32 in the rotor and is biased toward the cam
15 by the effect of a return spring 33. The slide 31 is
25 »itselfpositively driven in rotation by the pump body owing
to the provision Aof'keying on the shaft 9. This keying is
FIG. 7 is an »axial sectional view of a pump having
inner bearings and a central shaft;
formed, >inthe presently-.described embodiment, by the
yflat-faced end ¿35 of the shaft 9 which isengaged in the
PIG. '7a is a diagrammatic plan view `of :the pump of
FIG. 73'showing the forces acting on the barrel and the
resultant force thereof;
FIG. 7b lis a diagrammatic end view corresponding to
FIG. 7a;
~FIG. 8 is an axial sectional view yof a detail of the
Amounting of the piston shoes; and
s_waged portion 36 of the slide 31.
In the modification _shown in FIG. .4. the slide 31 is
,driven directly -by ‘the pump body through the medium
.of a'pin> í’r’lv or the like forming a key.
lIn the'embodiment shown in FIGS.»5 and 6, the bal
,ancing of fthe cram 15 isxensured by the abutment of the
FIG. 9 is lan axial sectionalview of a modification of 35 latter against protruding portions or bosses 3S, 38' pro
vided onrthe housing 2, the zone of contact between the
l6.21m #15 and the portions 38, 38' being a part-cylindrical
surface 39 the _axis of the `cylinder coinciding with the
pivot axis of the cam, namely, the axis of thepin 20.
example, of graphite. ‘The pump body, or rotor, is driven 40 The resultant >of the ¿thrusts exerted on theV cam by the
vpump pistonsy -is therefore in this embodiment balanced
in rotation bya yshaft 4 -through the medium of a gear 5
Sby 4the reaction iof the housing on the cam.
meshing with Aa ring gear >6 whose teeth are machined di
In the embodiment shown 'in FIG. >7, the pump is
rectly in the rotor 1.
¿the mounting .of -a .piston shoe.
In the embodiment shown in FIGS. 1_3, the pump com
-prises a-steel pump body or rotor 1 journalled in thehous
-ing ‘2 through the medium of 1a bearing 3 composed, for
mounted on ka central shaft. The elements corresponding
lThe position of bearing 3 is determined by calculation
as will -be'explained hereinafter with reference to `embodi 45 .to those of zthe pumps shown in FIGS. 1-3 or 5 and 6
~carry the same reference characters.
ment of FIG. vv7, in order that the resultantof the forces
:In this embodiment, the rotorl is ,mounted on a central
'applied on> rotor 1 falls Within the surface fof contact of
shaft 40 rigidly fixed in the housing 2 and extend-ing
the >distribution member and the rotor 1. Said calcula
through the pump. The rotor 1 is journalled on the
tion shows here that said bearing 3l ought to be located
--between the' vtransverse plane containing the pivot axis 20 50 shaft 40 through the medium of a main anti-friction or
roller bearing 41 and a secondary antiafriction or roller
of cam or swash plate 15 and vsaid distribution member,
'hearing `42, the play in the latter being greater than that
«in the immediate »vicinity of vsaid vtransverse plane.
in the bearing 41. The rotorY 1 is driven by the shaft 4
In order to improve the centering of the rotor 1 in the
through the medium of the gear 5 .meshed with the ring
`-housing 2, `there is provided an additional bearing 7 car
gear >«i directly machined in the rotor.
~-ried bythe housing and -in which is journalled the cy
"The main bearing 41 isrsituated at the end of the ro
~lindrical -extension'S of a shaft `9 which is fitted by a
_tapered portion 10 in the rotor '1 and held fast by a nut 11. . :tory adjacent the lcentrolcam 15 in a region which is de
»'The pump comprises pistons 12 -which slide in bores 13
termined by calculation in such manner that the result
formed'in ythe rotor, each of these bores being provided
ant of the forcesapplied on the rotor 1 is directed toward
with‘la liner 14, for example composedof silver, to reduce 60 'the distribution surface 43 and falls within the surface
of rcontact of this surface and the adjoining face of the
“The pump delivery or discharge vflow is controlled by `a
rotor 1, in order that,'owing to this arrangement, the
rotor 1 remains constantly»appliedpagainst the surface 43
ftiltable cam or swash plate 15 against the forward face
during pump operation and the presence of the secondary
of which the heads »16 of the pistons 12 bear through
the medium of their shoes 17 and of a ybearing member, 65 bearing 42 in the vicinity of the face 43 also ensures
or plate, 18~
_The _cam 15 carries two ears 19, 19’ provided with
vapertures in which is journalled a pivot pin v20 carried by
correct application when-the _pump is inoperative.
AThe above calculation is made in considering (see
FIGS.' 7a and 7b) the rotor 1 and pistons 12, as a whole,
_a support ,21 rigid with the housing. This pivot pin is
>submitted to the following forces:
adapted merely to maintain the cam 15 vin position and 70 (1) Resultaat Fp of the >forces exerted by cam 15
on piston shoes ,17;V
_is _only >subjected to a _small force owing to the provision
~of'balancing means which will now be described.
' ‘_,Providedin a bore 22 suitably disposed in the housing,
Y’is a piston y23 which is constantly applied by its forward
(g2) Driving force (or couple of forces) FM;
(3) Hydraulic Aforce FH exerted on rotor'l by the ñuid
kbottled up between said rotor »and ¿the distribution trans
>face- against the corresponding rear face 24 of «the cam 75 -verse wall 43;
(4) Resilient force FR exerted by the resilient mem
ber (33, see FIG. 1), if any, to apply the piston heads
16 against cam 15; ,
(5) Reaction Rp of bearing 41, the moment of which
is a function of the distance x between said bearing 41
and said transverse Wall 43;
(6) Reaction force RG of the transverse wall 43 on
rotor 1.
It is the above reaction force RG which is the subject
of the calculation and: RG=--e(Fp, FM, FH, FR, Rp).
For the calculation, the point of origin of the coordi
nates axes is chosen at the center of the distributor trans-r
verse wall 43; the axes 0x, oy are in the plane of said
wall 43, oy being directed towards the delivery port 45.
The magnitude and point of application of the diiîer 15
ent forces are determined by the following considerations:
(1) Resultant FP of the forces exerted by the cam 15
on the piston shoes 17 is perpendicular to said cam (pro
viding there is no substantial friction); its point ,of appli
cation is at the center of gravity of the half-circle having 20
a radius b equal to the boring radius of the piston bores,
and its component parallel to the axis oz balances the
force F generated by the delivery pressure of the pump
applied to half of the number of pistons 12.
(2) Driving force FM has its point of application at 25
the meshing point of driving gear 5 with thetoothed
ring 6, its direction is defined by the pressure angle of
the gear teeth, and its magnitude is determined by the
fact that themoment, relative to axis oz, of its compo
nent parallel to 0x, balances the moment, rela-tive to the 30
same axis, of FP.
When the rotor is driven through an axial drive, the
driving shaft applies to the rotor a pure torque.
(3) The hydraulic force FH applied to the rotor is
on the end 47 of the shaft 20 and extends out of the
housing through a suitable aperture.
In the embodiment shown in FIGS. 1 to 7, the spheri
cal heads 16 of the pistons 12 are set into the shoes 17
and the latter bear on the cam 15 by their flat faces 47.
In order to reduce friction, the shoe is covered on this
face with a suitable electrolytic deposit or the cam is
composed, for example, of graphite.
In the embodiment shown in FIG. 8, the shoe 17 corn
prises a recess 48 in which is disposed a thin friction plate
49 which protrndes from the face 4‘/ of the shoe. Thus,
the piston bears against the cam 15 solely through the
medium of this plate 49 which is provided with an aper
ture 5t) for the passage of lubricating oil. This plate is
composed of a metal having a good coefficient of friction,
«for example silver, and is easily changed when worn out.
In the modiñcation shown in FIG. 9, the frictionplate
is replaced by a substantially r’rusto-conical element 51
Whose flat lface 52, protruding from the face 57 of the
shoe 47, bears against the cam I5. The inner part 53 of
the element 5I, disposed in an aperture of corresponding
shape formed in the shoe, has a part-spherical concave
shape and extends inwardly of the shoe. The recess in the
shoe receiving the piston head has such shape that the
piston head 16 is merely retained by the edges 54, it bear
ing solely against the concave part 53 of the element 51.
Thus, friction both inside and outside the shoe only results
in Wear of the element 53 which is easily changed.
Although specific embodiments of the invention have
been described, many modifications and changes may be
made therein without departing from the scope of the
invention as defined in the appended claims. Thus, the
pistons need not be parallel with one another and the
shaft j‘ournalled in the lateral bearing could be mounted
parallel to oz and its point of application is at the center 35 in the rotor by means other than a tapered extension held
of gravity of the half-circle having a radius c equal to the
in place by a nut.
mean radius of the delivery and induction ports 45, 46,
What I claim is:
its magnitude is equal to the product of F and a factor
1. In a pump of the drum piston type comprising a
which depends on the balancing coefficient of the pump.
housing having a transverse wall and provided with an
(4) Force FR, in the case of an axial spring 33 (see
induction passageway and a delivery passageway opening
FIG. 1) is applied at the origin of the coordinates axes
on said transverse wall of said housing, a rotor mounted
and is parallel to oz.
for rotation about an axis in said housing and having a
(5) The reaction force Rp of the bea-ring 4l is perpen
lateral face in contact with a corresponding surface of
dicular to oz and balances all components of the afore
said transverse Wall and bores opening on said lateral
said forces which are perpendicular to oz.
face, pistons disposed for reciprocation in said bores and
(6) And the reaction force RG of the transverse wall
having each a part-spherical head outside said rotor, a
43 on rotor 1 is parallel to oz; its magnitude is equal to:
cam having a ñat face cooperating with said heads of
FH-F-FR and its point of application in the plane of
transverse wall 43 is determined by writing that the
said pistons for controlling the movement of said pistons
in said rotor, a shoe mounted on each of said heads of
moments of said force RG relative to axes ox and oy 50 said pistons and having a flat face resting against the said
are, respectively, equal to the sums of moments of afore
ñat face of said cam, a retaining plate for biasing said
said forces relative to the corresponding axes.
shoes against said cam, a spring biased member axially
and slidingly mounted in said rotor, said spring biased
member and said plate providing contacting surfaces be
inside the circle having the radius r of the distributor 55 tween the spring biased member and the plate, said con
transverse member 43 give the limits between which is
tacting surfaces providing grooves and projections fitting
to be located the main bearing 41, to be sure that rotor 1
in said grooves for positively driving the plate via the
remains always correctly applied against said transverse
spring biased member.
wall 43 to provide a perfect working of the pump.
2. In a pump of the drum piston type co-mprising a
The coordinates of said point of application of RG
being thus calculated, the conditions for said point to be
The secondary bearing 42 is in the sa-me transverse 60 housing having a transverse wall and provided with an
plane perpendicular to the shaft 40 as the ring gear 6
induction passageway and a delivery passageway opening
which is obviously most advantageous and only possible
with a rotor mounted on a central shaft.
on said transverse wall of said housing, a rotor mounted
for rotation about an axis in said housing and having a
The line of meshing between the gears 5 and 6 is in the
lateral face in contact with a corresponding surface of
same plane as the axis of the induction passageways 44 65 said transverse Wall and bores opening on said lateral
and delivery passageways 45 and on the side of the axis
face, pistons disposed for reciprocation in said bores and
of the rotor opposed to that of the delivery passageway
having each a part-spherical head outside said rotor, a
45. The application of the rotor against the distribution
cam having a flat face cooperating with said heads of
surface 43 is thereby still further improved.
The cam 15 abuts, through the medium of a cylindrical 70 said pistons for controlling the movement of said pistons
in said rotor, a shoe mounted on each of said heads of
boss formed thereon, against the parts 38 having corre
said pistons and having a ñat _fa-ce resting against said
sponding shape of the housing 2 and can be tilted by a
dat face of said cam, a retaining plate for applying said
shaft 20 which is integral therewith and disposed in a
shoe against said cam and having a hemispherical por
corresponding bore in the housing. The tilting of the
cam 20 is controlled by a control lever 46 which is ñxed 75 tion, a spring biased member axially and slidingly
tween the Vtransverse plane containing Vthe Aaxis oirocking
mounted in said rotor but keyed in rotation with _said
rotor and having a hemispherical portion fitting with said
movement of said cam and said’transverse’walrlat .ai'disyA
hemispherical portion of said retaining plate'for urging
tance from said transverse Wall such yas to have said _reac-l
said plate landsaid shoes towards said cam, grooves on
tion force exerted lby said transverse vwall Non' said vrotor
fall inside said corresponding surface of Asaid1transvelrse
one ,of said corresponding hemispherical portions Vof said
Wall and be directed towards said rotor.
retaining plate and said Vspring biased members, _and pro
iections on the other of said hemispherical portions en
4. In la pump as in claim 3, further comprising aV sec
gaging vvith and cooperating with said grooves.
ondary bearing located substantially in the plane containf
induction passageway and adelivery passageway opening
_5. VIn a pump as‘in claim 3, wherein said ldelivery _pas
sageway is located in the axial plane >containing _thelineof mesh between said toothed ring and said gear on the
side of >the axis of the ïotor opposed to that y,of said line
ing said toothed ring and supporting said rotor with `a
3. I_n a pump ofv the drum piston type comprising a
housing having a‘transverse Wall and provided with an l0 play exceeding the play of said main bearing.
on said transverse Wall of said housing for circulation
ofthe fluid to be circulated by said pump,` a rotor mounted
Ifor rotation about an axis in said housing and having a
lateral face incontact With a corresponding surface of 15
~said transverse Wall exerting on said rotor a reaction force
substantially perpendicular ,to said lateral face and bores
opening on said‘lateral face,- pistons disposed for recipro
cation in said bores and having each a head outside said
rotor, a cam cooperating with said heads for controlling 20
the'movement of rsaid pistons in said rotor comprising a
Ísupport mounted for rocking movement about an axis ex
ltending at right angles to the axis of rotation of ,Said
rotor and exerting'on >said piston heads forces ywhich have
va resultant perpendicular to saidicam, -resilient means
urging said pistons against ysaid cam thereby exerting a
force .on said rotor, a -toothed ring 'directlyv machined in
the lateral face .of said rotor,~ and Aa 4driving shaft >having
lits _axis parallel to .the axis of rotation of said rotor, a
gear carried by said driving shaftand Ámeshing _with said
ltoothed ring for rotating said rotor and .exerting on said
_rotor ya driving force, a .main bearing »for supporting said
rotor in Vsaid Vhousing and `exertingon said ‘rotor a bearing
reaction force substantially perpendicular to said Y.axis of
,said `rotor and _forming with said resultant force .exerted
by said cam on said piston heads, said-,hydraulic force,
said driving force, said force exerted byfsaid ¿resilient
sultant, said main ,bearing being located in a plane be
References Cited in the tile `of this patent
» 1,418,951
Martin _______________ _.. June 6, A192?.
Carey ..-_Q___________ __Ápr. 23, 1929
Thomas ...._...'._V_ _______ _.. Apr. «9,4193-5
Schindler ______________ _; Dec. 8,1936
Herman4 _________ __`_A___ -Mayi2`6', »1942
Wright _______ _-,_ ____ __ Ang. 23, .1949
Ferris ____ __v.`____l____p_'_..o'ct,f11, 11949
Adams ____-_-_.___s .... __ Apr. 4, 1950
Gabriel À__-_______ 1....'.5112615.- 27, 1951
Ruben ______________ _~__ Apr. 17,1951
Born et a-l ____________ -_ June 23,1953
Bonnette et al. ________ „Jans-11', 1955
Ferris _________ _d ____ __’_.'Sept. 6, `11955
Poulos ______________ __'- Fe'b. 7, 1956
.Keel ____ __j _________ __'__ Jan; 8', 1957
>Aspelin __________ __',____<Ju1y123, '1957
Budzich ____ _.’..r._-_j___.._ ¿Man '311, 1959
-orshans-ky `___-'_'-__’_"__j'__'1ú1`y p21; V1’9'5'9
Switzerland ___________ -_'Mar.11, y1927
meansand said reaction -force'exerted by said transverse
,wall on said rotor a system of forces having a zero re 40
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