Pumps – Condition responsive control of drive transmission or pump... – Adjustable cam or linkage
Reexamination Certificate
1999-09-14
2001-07-31
Freay, Charles G. (Department: 3746)
Pumps
Condition responsive control of drive transmission or pump...
Adjustable cam or linkage
C417S053000, C417S269000
Reexamination Certificate
active
06267561
ABSTRACT:
TECHNICAL FIELD
This invention relates to a variable delivery, fixed displacement fluid pump and, more particularly, to a variable delivery, fixed displacement pump suitable for pressurizing actuation fluid for fluid actuated diesel engine unit injectors or other fluid actuated devices.
BACKGROUND ART
Axial, swash plate type piston pumps are well known in the art. In cases where the swash plate angle is fixed with respect to its axis of rotation, fluid delivery from the pump is dependent only upon the angular velocity of the rotating swash plate. Thus, increasing the angular velocity of the swash plate provides a higher delivery rate, and decreasing the angular velocity of the swash plate provides lower delivery rate. In certain applications, such as fluid actuated diesel injection systems, for example, the swash plate is driven directly by the engine and the angular velocity of the swash plate is dependent upon engine speed. As a result, pump delivery is dependent upon engine speed. However, there are many instances in which it is desirable to control pump delivery independent of engine speed or angular velocity of the swash plate.
To allow variable fluid delivery from the pump independent of angular velocity of the swash plate, it is well known to utilize a swash plate that can be moved to various angles relative to its axis of rotation to thereby vary the displacement of the pump. Such a pump is often referred to as a wobble plate pump. Wobble plate pumps provide satisfactory variable delivery for many applications, but they are often mechanically complex and more prone to failure.
So-called “sleeve metered” pumps have been developed to achieve the variable delivery available from wobble plate pumps without a complex mechanical pump structure. An exemplary sleeve metered pump is illustrated in U.S. Pat. No. 5,603,609, granted Feb. 18, 1997, to Kadlico. In general, sleeve metering utilizes a fixed angle swash plate, thus providing a fixed displacement pump. Each piston is provided with a radial vent port in a portion thereof that does not travel within the cylinder so that fluid is vented through the vent port during the compression stroke. A sleeve is slidably disposed around the portion of each piston that does not travel within the cylinder. As the piston moves during the compression stroke, fluid is vented through the vent port of the piston until the vent port moves through the sleeve, which closes the port. When the vent port is closed, fluid is compressed and pumped at high pressure from the cylinder through an outlet port. Thus, moving the sleeve to cover the vent port longer or shorter durations during the compression stroke varies fluid delivery from the pump. Like wobble plate pumps, sleeve metered pumps are also satisfactory for many applications, but they often require complex mechanical systems and controls to move the sleeves relative to the pistons and are thus more prone to failure.
This invention is directed to overcoming one or more of the problems or concerns set forth above.
DISCLOSURE OF THE INVENTION
In one aspect of this invention, a variable delivery, fixed displacement pump, comprises a cylinder block defining at least one cylinder and at least one piston having a portion thereof reciprocal through a stroke within the at least one cylinder. The piston and the cylinder together define a variable volume fluid compression chamber having a delivery outlet. An angled swash plate is axially spaced from the cylinder block and drivingly connected to the at least one piston to reciprocate the piston relative to the cylinder block. The swash plate rotates about a swash plate axis and disposed at a fixed angle relative to the swash plate axis. The relative axial spacing between the swash plate and the cylinder block is adjustable without changing the fixed angle of the swash plate relative to the swash plate axis of rotation.
In another aspect of this invention, the relative axial spacing between the swash plate and the cylinder block is adjusted by moving the swash plate along its axis of rotation relative to the cylinder block.
In yet another aspect of this invention, a method for controlling the delivery rate of a fixed displacement pump is disclosed. The pump has a rotatable, angled swash plate drivingly connected with at least one piston to thereby move the piston through a reciprocal stroke within a cylinder defined by a cylinder block axially spaced from the swash plate. The piston and cylinder together define a fluid compression chamber having a delivery outlet. The method comprises providing a vent port from the fluid compression chamber operable to vent fluid from the compression chamber during at least a portion of the reciprocal stroke of the piston. The piston and cylinder cooperating to close the vent port during another portion of the reciprocal stroke of the piston so that fluid within the compression chamber is pumped through the delivery outlet. The method further comprises providing relative axial motion between the swash plate and the cylinder block to adjust the axial spacing between the swash plate and the cylinder block, wherein the axial spacing between the swash plate and the cylinder block determines the duration of the another portion of the reciprocal stroke of the piston.
Other features and advantages of the present invention will be apparent from the following description and the accompanying drawings.
REFERENCES:
patent: 3150603 (1964-09-01), Yarger
patent: 3249052 (1966-05-01), Karlak
patent: 3482521 (1969-12-01), Wolf
patent: 4028015 (1977-06-01), Hetzel
patent: 4129063 (1978-12-01), Ifield
patent: 4492527 (1985-01-01), Swain et al.
patent: 4600364 (1986-07-01), Nakatani et al.
patent: 5417552 (1995-05-01), Kayukawa et al.
patent: 5702235 (1997-12-01), Hirota et al.
patent: 5915928 (1999-06-01), Murase et al.
Caterpillar Inc.
Cheek John J.
Freay Charles G.
Gray Michael K.
Huber Michael R.
LandOfFree
Variable delivery, fixed displacement pump does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Variable delivery, fixed displacement pump, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Variable delivery, fixed displacement pump will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2473938