LOW PULSATION PUMP MECHANISM AND PUMP

POMPE ET MECANISME DE POMPE A FAIBLE PULSATION

English Abstract

ABSTRACT
An improved low pulsation positive displacement pump includes a
cross head that is rotationally stabilized with respect to the housing of the
pump by a screw and slot arrangement for improved cam and cam follower
alignment with low resultant horizontal forces.

Claims

I claim:
1. A low pulsation pump mechanism comprising:
a housing:
a camshaft rotatably mounted about a first axis
within said housing;
at least one cam fixed to said camshaft;
at least one cam follower corresponding to said
at least one cam and rotatably mounted to one end of a
follower arm about an axis parallel to said first
axis;
means for biasing said cam follower against said
cam;
at least one cross head corresponding to and
being fixed to the other end of said follower arm;
a piston rod fixed at one end to said cross head;
means for preventing rotation of said cross head
relative to said housing when said cross head and said
piston rod undergo linear motion in response to
rotation of said camshaft and said cam.
2. A pump mechanism according to claim 1, wherein
said cross head is cup-shaped having a bottom
closed end and a top open end.
3. A pump mechanism according to claim 2, wherein
said bottom closed end is fixed to said other end
of said follower arm in generally coaxial alignment.
4. A pump mechanism according to claim 1, wherein
said piston rod is fixed at one end to said cross
head in generally coaxial alignment.
5. A pump mechanism according to claim 1, wherein
said means for biasing said cam follower against
said cam comprise a spring.

6. A pump mechanism according to claim 1, wherein
said means for preventing rotation of said cross
head relative to said housing comprise an extension
member fixed with respect to said housing and
extending radially inward into an elongated slot on
said cross head.
7. A pump mechanism according to claim 6, wherein
said extension member comprises a screw.
8. A pump mechanism according to claim 6, wherein
said elongated slot extends generally parallel to
said piston rod.
9. A pump mechanism according to claim 5, wherein
said spring is fixed at one end relative to said
housing and is in contact with said cross head at the
other end.
10. A pump mechanism according to claim 9, wherein
said spring is compressed when said cross head
moves away from said camshaft.
11. A pump mechanism according to claim 1, wherein
said at least one cam is fixed to said camshaft
by at least one key.
12. A pump mechanism according to claim 11, wherein
said pump mechanism comprises a plurality of cams
fixed to said camshaft.
13. A pump mechanism according to claim 12, wherein
said cams are spaced apart from each other by
spacers.
14. A pump mechanism according to claim 13, wherein
said spacers comprise ring-shaped members fixed
about said camshaft.
15. A low pulsation pump comprising:
a housing;
a camshaft rotatably mounted about a first axis
within said housing;
at least one cam fixed to said camshaft;

at least one cam follower corresponding to said
at least one cam and rotatably mounted to one end of a
follower arm about an axis parallel to said first
axis;
means for biasing said cam follower against said
cam;
at least one cross head corresponding to and
being fixed to the other end of said follower arm;
a piston rod fixed at one end to said cross head;
means for preventing rotation of said cross head
relative to said housing when said cross head and said
piston rod undergo linear motion in response to
rotation of said camshaft and said cam
at least one cylinder corresponding to each of
said at least one cross head having a pump chamber;
an intake and ouptut manifold corresponding to
each of said at least one cylinder;
an output check valve corresponding to each of
said at least one cylinder permitting flow from the
corresponding pumping chamber to the output manifold;
at least one piston corresponding to each of said
at least one cylinder and reciprocable within the
corresponding cylinder; and
a seal carried by each piston for sealingly
engaging the corresponding cylinder.
16. A pump according to claim 15, wherein
said cross head is cup-shaped having a bottom
closed end and a top open end.
17. A pump according to claim 16, wherein
said bottom closed end is fixed to said other end
of said follower arm in generally coaxial alignment.
18. A pump according to claim 15, wherein
said piston rod is fixed at one end to said cross
head in generally coaxial alignment.
19. A pump according to claim 15, wherein
said means for biasing said cam follower against
said cam comprise a spring.

20. A pump according to claim 15, wherein
said means for preventing rotation of said cross
head relative to said housing comprise an extension
member fixed with respect to said housing and
extending radially inward into an elongated slot on
said cross head.
21. A pump according to claim 20, wherein
said extension member comprises a screw.
22. A pump according to claim 20, wherein
said elongated slot extends generally parallel to
said piston rod.
23. A pump according to claim 19, wherein
said spring is fixed at one end relative to said
housing and is in contact with said cross head at the
other end.
24. A pump according to claim 23, wherein
said spring is compressed when said cross head
moves away from said camshaft.
25. A pump according to claim 15, wherein
said at least one cam is fixed to said camshaft
by at least one key.
26. A pump according to claim 25, wherein
said pump mechanism comprises a plurality of cams
fixed to said camshaft.
27. A pump according to claim 26, wherein
said cams are spaced apart from each other by
spacers.
28. A pump according to claim 27, wherein
said spacers comprise ring-shaped members fixed
about said camshaft.
29. A pump mechanism according to claim 1, wherein
each of said at least one cam is symmetrical in
profile.
30. A pump according to claim 15, wherein each of
said at least one cam is symmetrical in profile.

Description

a
63-11394
IMPROVED LOW PULSATION PUMP MECHANISM AND PUMP
BACKGROUND OF THE INVENTION
This invention relates to positive displacement
pumps, and more particularly, to a low pulsation
positive displacement pump mechanism and pump.
The pump mechanism of the present invention
utilizes a symmetric cam profile such that the
camshaft can be installed without a need to
distinguish the ends of the camshaft for reliable and
efficient assembly. The camshaft also provides
versatility in that the drive end of the camshaft can
be engaged from either side of the pump mechanism.
The pump mechanism also utilizes a cross head that is
rotationally stabilized with respect to the housing of
the pump by a screw-slot arrangement. The screw-slot
arrangement is superior in providing maximum stability
and minimum horizontal force to the cross head.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG.1 is a cross-sectional view of a pump
mechanism according to the present invention.
FIG.2 is cross-sectional orthogonal view of an
assembled camshaft according to FIG.1
FIG.3 is a cross-sectional view of a pump
according to the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to FIG.S 1-3, a preferred embodiment of
the low pulsation pump and pump mechanism includes a
housing (10) encasing the pump and pump mechanism. A
camshaft (12) having one or a plurality of cams (14)
is rotationally mounted within the housing (10). Each
cam (14) preferably has a symmetric profile. The
camshaft (12) can be oriented with respect to either

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side of the housing (10). A cam -follower (16) is
mounted on a follower arm (17) and provided in biased :
contact with each cam (14). Means are provided to
prevent rotation of each follower arm (17) relative to
the respective cam.
Specifically referring to FIG.3, each cam :
follower (16) transmits the rotational motion of the
cam (14) to the piston rod (18) which, in turn,
transfers the rotational motion as linear motion to a
piston (20). The piston (20) sealingly engages and is
reciprocable within a cylinder (22) secured to a
manifold assembly (24) releasably attached to the
housing (10). The manifold assembly (24) includes an
intake chamber (26), an output chamber (28) and a
pumping chamber (30) communicating with the cylinder
(22). A check valve (32) separates the intake chamber
(26) from the pumping chamber (30) and permits fluid
flow only form the intake chamber (26) to the pumping ~:
chamber (30). A similar check valve (34) separates
the output chamber (28) from the pumping chamber (30)
and permits fluid flow only from the pumping chamber
(30) into the output chamber (28). Reciprocation of
the piston (20) in response to the follower (16)
following the cam (14) will result in fluid being
drawn from the intake chamber (26) into the pumping
chamber (30) and then forced into the output chamber
(28).
Specifically shown in FIG.1 are means (36, 38,
40) for preventing rotation of each follower arm (17)
with respect to the corresponding cam (14) in order to
maintain contact between the follower (16) and cam
(14). A cup-shaped cross head (40) having a bottom
closed end and a top open end is fixed to the follower
arm (17) at the bottom end. A piston rod (18) is
fixed generally concentrically within the cross head
(40). The cross head (40) reciprocates with the
follower arm 17 and piston rod 18 in response to
~or ~ } ~ ~

_ 3 _ ~ I ~` 12 2.~
rotation of the camshaft 12 and cam 14. An extending
member, such as a screw (36) or other suitable member,
is fixed relative to the housing 10 and extends into a
longitudinal groove or slot (38) to maintain
s rotational stability of the cross head (40), follower
arm (17) and cam follower 16 during reciprocation. A
spring (42) or other suitable biasing member is
provided to resiliently bias the cross head (40), and
thus the follower (16), against the cam (14). As
illustrated in the preferred embodiment, a spring (42)
is fixed with respect to the housing (10) and
positioned in engagement with the cross head (40).
With specific reference to FIG.2, there is shown
a camshaft (12) having cams (14) attached to the
camshaft (12) by conventional keys (44). Each cam
(14) is separated on the camshaft (12) by spacers
(46). Due to the symmetry of each cam (14), the drive
end (50) can be positioned at either side of the
housing (10).
While the embodiment of the present invention has
been disclosed herein, it will be appreciated that
various changes and modifications may be made thereto
without departing from the spirit of the invention as
defined by the scope of the claims.

Representative Drawing