Information
-
Patent Grant
-
6478548
-
Patent Number
6,478,548
-
Date Filed
Monday, November 20, 200024 years ago
-
Date Issued
Tuesday, November 12, 200222 years ago
-
Inventors
-
Original Assignees
-
Examiners
- Walberg; Teresa
- Robinson; Daniel
Agents
-
CPC
-
US Classifications
Field of Search
US
- 417 221
- 417 218
- 417 212
-
International Classifications
-
Abstract
The invention relates to a radial piston pump (1) with an eccentric actuator unit (19), the radial piston pump (1) having several pumping units (20) driven by a common drive shaft (18). A central axis (35) of a circumferential bearing surface (37) of an actuator eccentric (33) designed for displacing pump pistons (24) of the pumping units (20) extends at an angle relative to a central axis (31) of the drive shaft (18) or an actuator unit (19) incorporating the actuator eccentric (33).
Description
The invention relates to a radial piston pump having an eccentric actuator unit with several pump pistons driven by a common drive shaft.
A number of radial piston pumps are known, by means in which a delivery volume can be adjusted by means of an eccentric. The disadvantage of these is that the eccentric surfaces run parallel with a drive shaft and the delivery volume can therefore only be adjusted by displacing the central axis of the eccentric relative to the central axis of the drive shaft. The delivery volume is often adjusted purely on the basis of pressure. Radial piston pumps of this type are very complex to manufacture because a separate drive has to be provided for the pressure medium, to which external pressure is applied.
The objective of the invention is to provide a pumping system of the type having a radial piston pump with an eccentric actuator unit, which will allow largely automatic regulation of the delivery volume depending on the system pressure during operation.
This object is accomplished by the invention with a radial piston pump comprising a plate-shaped housing having bores for conveying a fluid medium, a drive unit joined to the housing at one side thereof and having a drive shaft projecting through the housing, a storage container for the fluid medium fluid-tightly joined to the housing at a side thereof opposite to the one side, and pumping units comprising pump pistons arranged at the opposite side of the plate-shaped housing, the pump pistons circumferentially surrounding the drive shaft and being radially displaceable relative thereto. An eccentric actuator unit radially displaces the pump pistons, the actuator unit having an axially extending bore receiving the drive shaft, being axially displaceably mounted on the drive shaft and keyed thereto for rotation therewith, and the actuator unit to the axis of the drive shaft and a like inclined surface bearing on the pump pistons.
The surprising advantage of this system is that in order to regulate the pumping rate of a pump equipped with any number of pumping units to cope with the demands of prevailing requiroments, a mechanically simple and hence reliable control system is provided between the drive unit and the pumping system, designed to permit automatic regulation so that predetermined work rates can be obtained irrespective of the consumers used, and the strokes of the pump pistons and hence their delivery rate may be varied.
A reproducible initial position will remain unchanged for a predetermined, structurally created eccentricity if a biasing mechanism is provided for displacing the actuator unit into an end position against a stop axially spaced from the housing, the biasing mechanism comprising return springs arranged in, and substantially parallel to, the axially extending actuator unit bore.
A bearing design which is capable of absorbing the spring forces with virtually no wear is provided with an annular bearing seat supporting the return springs at ends thereof opposite the stop. The bearing seat is a ring surrounding a cylindrical portion of the actuator unit axially projecting from the cylindrical body having an inclined axis, further comprising a radial bearing supporting the bearing ring and bearing the cylindrical portion of the actuator unit.
If a spring couples the actuator unit to the drive shaft for locking the actuator unit against rotation relative to the drive shaft, the rotary motion of the drive shaft is transmitted via the biasing spring to the actuator unit free of backlash, without restricting the capacity of the actuator unit to move axially on the drive shaft.
Advantageously, the radial piston pump further comprises a casing circumferentially surrounding an end of the actuator unit remote from the drive unit, and an actuator arranged in the casing. A thrust bearing is arranged between a pressure plate of the actuator and an end face of a recess of the actuator unit. A biasing mechanism displaces the actuator unit into an end position against the pressure plate of the actuator, and the actuator comprises a pressure medium activated plunger exerting an axial bias force opposite the bias force exerted by the biasing mechanism. The plunger is connected to the pressure plate by a press-fit to prevent displacement.
As a result of these, the delivery volume can be controlled externally in order to adjust the pumping rate to an adjustment curve predetermined on the basis of specific operating conditions and the mechanism used for this purpose can be obtained using simple and reliable transmission components known from the prior art.
If the pumping units have outlets communicating with each other by bores in the plate-shaped housing, the bores constituting pressure lines for the fluid medium, assembly is simplified since loss of load due to the pipework is reduced to a minimum and faults caused by leakage which might otherwise occur due to the stress of vibration on screw fittings and pipework are avoided.
A compact structure is provided if a flanged bearing plate affixes the plate-shaped housing and a pump housing for the pump pistons arranged at the opposite side thereof to the drive unit.
Advantageously, the pistons carry piston shoes in contact with the inclined bearing surface of the cylindrical body of the actuator unit. The piston shoes are able to move on all sides enabling them to adapt to every possible angle.
The invention will be described in more detail with reference to the examples of embodiments illustrated in the drawings.
Of these:
FIG. 1
is a simple schematic illustration of the structure of a radial piston pump with an integrated actuator unit of the type proposed by the invention;
FIG. 2
is a side view of the radial piston pump illustrated in
FIG. 1
;
FIG. 3
is a side view of the actuator unit proposed by the invention, seen in section;
FIG. 4
illustrates the pump housing with the mounted actuator unit and actuator proposed by the invention to enable an axial displacement of the actuator unit;
FIG. 5
illustrates another embodiment enabling axial displacement of the actuator unit proposed by the invention;
FIG. 6
is a detailed illustration showing the forces that are applied by the actuator unit illustrated in FIG.
5
.
Firstly, it should be pointed out that the same parts described in the different embodiments are denoted by the same reference numbers and the same component names and the disclosures made throughout the description can be transposed in terms of meaning to same parts bearing the same reference numbers or same component names. Furthermore, the positions chosen for the purposes of the description, such as top, bottom, side, etc,. relate to the drawing specifically being described and can be transposed in terms of meaning to a new position when another position is being described. Individual features or combinations of features from the different embodiments illustrated and described may be construed as independent inventive solutions or solutions proposed by the invention in their own right.
FIGS. 1 and 2
illustrate a radial piston pump
1
, consisting of a pumping system
2
and a drive unit
3
. The drive unit
3
in this example has a motor
4
, which is activated by a control system
5
. The radial piston pump
1
is mounted on a base plate
6
or a tubular frame, etc., which is preferably supported on a standing surface
8
by means of vibration-damping feet
7
. The pumping system
2
is arranged in a supply container
9
and is constantly surrounded by the medium
10
contained in the supply container
9
. This medium
10
is preferably a pressuring medium such as hydraulic oil, for example. The supply container
9
is provided with an inlet opening
11
enabling it to be filled with the medium
10
and the closure system is provided with a liquid level indicator
12
of a known type by means of which the level of the supply container
9
is controlled. At the deepest point of the supply container
9
is an outlet opening
14
closed off by a screw
13
, by means of which the supply container
9
is emptied, for example to change the medium
10
at regular intervals.
The supply container
9
is preferably made from a known type of sheet metal and is joined to a housing component
16
by means of a flange
15
running around the end face, e.g. is screwed thereto, although other possible fixing means designed to provide a tight seal may also be used. The housing component
16
is joined to a flanged plate
17
, which is designed to receive the drive unit
3
disposed opposite the housing component
16
, e.g. having a centring shoulder to provide a centred mounting of the motor
4
.
The pumping system
2
in turn consists of a drive shaft
18
projecting out from the drive unit
3
or the motor
4
and an actuator unit
19
slidably mounted thereon in an axial direction and cooperating with the pumping units
20
mounted on the housing component
16
.
The pumping units
20
are standard delivery components for a medium
10
, such as hydraulic oil, and as such are of the self-suction type. A pump piston
24
provided in a bore
22
of a pump housing
21
adjustably acts against the action of a spring
23
. In an end region projecting out from the pump housing
21
, the pump piston
24
has what will be referred to as a piston shoe
25
, which bears on the actuator unit
19
due to the action of the spring
23
or the force applied by the medium
10
to the pump piston
24
.
In the embodiment illustrated here, an actuator
26
, supplied by an external pressure generator, is provided as a means of displacing the actuator unit
19
in the axial direction of the drive shaft
18
, enabling the actuator unit
19
to be displaced along the drive shaft
18
to produce an externally definable volume and pressure curve of the pumping system
2
.
As may be seen more clearly from
FIG. 2
, pumping units
20
, of which there are six for example, are disposed on the housing component
16
laid out radially around the drive shaft
18
. The number of pumping units may be freely selected and will depend on requirements, particularly with regard to the delivery rate of a radial piston pump
1
of this type. As mentioned above, these pumping units
20
are of the self-suction type, which suck in the medium
10
through inlet orifices when an under-pressure prevails in the bore
22
and discharge it via pump outlets
27
when the pump piston
24
is displaced by means of the actuator unit
19
as the pressure builds up. The pump outlets
27
of the pumping units
20
are connected to one another to form a line by means of bores
28
provided in the housing component
16
, so that a common pressure is allowed to build up across all pumping units
20
. As a result of this design in which all pump outlets
27
are connected to one another in a line across the bores
28
, the medium
10
can be discharged at an outlet
29
at a relatively constant pressure and fed to a consumer, e.g. a hydraulically operated tool.
FIG. 3
shows a side view of the actuator unit
19
, seen in section. The actuator unit
19
has a mounting bore
30
for receiving the drive shaft
18
of the drive unit
3
. The mounting bore
30
and the drive shaft
18
of the drive unit
3
have a common central axis
31
, which extends across the entire length of the actuator unit
19
, thereby enabling it to rotate about the central axis
31
. Also disposed in the mounting bore
30
and extending across the entire length of the mounting bore
30
is a groove-shaped recess
32
, provided as a means of receiving a retaining means, such as a biasing spring for transmitting the rotary motion of the drive shaft
18
. The actuator unit
19
forms an actuator eccentric
33
, provided as an inclined cylindrical body
34
, a central axis
35
of the cylindrical body
34
running at an acute angle to the central axis
31
of the drive shaft
18
.
A lateral surface
36
of the actuator eccentric
33
or cylindrical body
34
forms a bearing surface
37
for the pump pistons
24
. Consequently, the central axis
35
of the circumferential bearing surface
37
of the actuator eccentric
33
is directed at an angle, in particular an acute angle
38
relative to the central axis
31
of the drive shaft
18
or the actuator unit
19
incorporating the actuator eccentric
33
. The actuator unit
19
also has mounting bores
39
extending parallel with its central axis
31
, which may be designed to receive any type of return members for the actuator eccentric
33
and the actuator unit
19
. A length
40
of the actuator eccentric
33
measured parallel with the central axis
31
of the actuator unit
19
is essentially smaller than a total length
41
of the actuator unit
19
.
A recess
42
or a bore
43
for receiving a thrust bearing is provided on the end face of the actuator unit
19
remote from the drive unit
3
. This bore
43
is of a slightly smaller diameter
44
than the mounting bore
30
, preventing the drive shaft
18
from projecting fully through the actuator unit.
The angle
38
subtended by the central axis
31
of the drive shaft
18
and the central axis
35
of the actuator eccentric
33
or cylindrical body
34
can be freely selected depending on the desired displacement characteristics but is between approximately 5° and 15°.
FIG. 4
provides a detailed diagram of the pumping system
2
with the actuator
26
and the actuator unit
19
or actuator eccentric
33
mounted on the drive shaft
18
. As may be seen from this diagram, the actuator unit
19
with its actuator eccentric
33
is axially pushed onto the drive shaft
18
so that a central axis
31
of the actuator unit
19
is aligned with a central axis of the drive shaft
18
. As a result of this layout, the actuator unit
19
incorporating the actuator eccentric
33
is mounted on the drive shaft
18
so as to slide axially along the central axes
31
of the actuator unit
19
and the drive shaft
18
. In order to transmit the rotary motion of the drive shaft
18
to the actuator unit
19
incorporating the actuator eccentric
33
, a biasing spring
47
is inserted in the recess
32
of the mounting bore
30
described above and in the recess
46
in the drive shaft
18
matching the recess
32
. The purpose of this biasing spring
47
is to transmit the rotary motion of the drive shaft
18
to the actuator unit
19
and permit an axial displacement of the actuator
19
incorporating the actuator eccentric
33
in an axial direction along the central axis
31
, i.e. the actuator unit
19
with the actuator eccentric
33
is locked onto the drive shaft
18
in rotation by the biasing spring
47
. A screw
49
is screwed into an end face
48
of the drive shaft
18
to prevent any axial displacement of the biasing spring
47
.
In the embodiment illustrated here, depicting one possible embodiment of the actuator
26
used to displace the actuator unit
19
, a housing
50
is mounted more or less coaxially on the housing component
16
surrounding the actuator unit
19
and is provided with orifices so that the actuator unit
19
as a whole runs in an oil bath formed by the medium
10
.
To enable an axial displacement of the actuator unit
19
with the actuator eccentric
33
as described above, the actuator
26
is arranged in and end region
51
of the housing
50
remote from the drive unit
3
, which may be operated by an external pressure system or by any other drive unit. The actuator
26
has a plunger
54
to which pressure is applied via a connecting piece
52
and a supply line
53
, a central axis
55
of the plunger
54
running along a central axis of the actuator unit
19
and a central axis
31
of the drive shaft
18
. Prior to assembling the housing
50
, this plunger
54
is positioned on the housing component
16
by means of a threaded member
56
, in which the plunger
54
is mounted in a bearing seat. The threaded member
56
has a peripheral seal
57
in the direction towards the connecting piece
52
in order to prevent any pressurised liquid from penetrating the threaded member
56
, ensuring that smooth operation of the plunger
54
will not be adversely affected.
A pressure plate
58
is attached to the end region of the plunger
54
facing the actuator unit
19
. This pressure plate
58
has an approximately T-shaped cross section and lies with an end face
59
co-operating with the plunger
54
on an internal face
60
of the housing
50
when the plunger
54
is in the non-pressurised state so that the pressure plate
58
co-operates with the actuator unit
19
at its housing-side end region.
A projection
61
of the plunger
54
extending along the central axis
55
is of a diameter
62
which is preferably smaller than the diameter
44
of the bore
43
in the actuator unit
19
. Arranged on or attached to the radial peripheral flank
63
of the pressure plate
58
is a thrust bearing
64
, which ensures that the actuator unit
19
can rotate unhindered even though the plunger
54
is mounted on the actuator unit
19
. At least one guide pin
65
is provided in the flank
63
by means of a push-fit mechanism and extends in the direction of the connecting piece
52
. This guide pin
65
is slidably mounted in an axial direction in a bore
66
provided in the housing
50
. The pressure plate
58
is locked onto the plunger
54
by the guide pin
65
to prevent rotation and exerts a displacement force on the actuator unit
19
rotating with the drive shaft
18
by means of a thrust bearing
64
inserted in between.
Mounting bores
39
are arranged in the actuator unit
19
or the actuator eccentric
33
, the central axes
67
of these mounting bores
39
extending parallel with the central axis
55
. These mounting bores
39
are designed to receive return springs
68
, which bear against a bearing seat
69
and absorb an axial force on the housing component
16
by means of a bearing arrangement. The return springs
68
or mounting bores
39
may be of any chosen length but the return forces must be distributed around the periphery so that they ensure that the actuator unit
19
slides parallel with the central axis
31
of the drive shaft
18
.
The pumping units
20
are arranged in a star-shaped layout on the housing component
16
at a distance
70
from the central axis
31
of the drive shaft
18
, these pumping units
20
incorporating the pump pistons
24
extending perpendicular to the central axis
31
. In end region of the pump piston
24
disposed in the direction of the actuator unit
19
, piston shoes
71
which can move on all sides are provided, and bear on the circumferential lateral face
37
of the actuator eccentric
33
. Because they are able to move on all sides, the piston shoes conform to an inclined position of the bearing surface
37
. As a result, the pumping units
20
are driven by means of the actuator eccentric
33
, the central axis
35
of the actuator eccentric
33
being disposed at an acute angle
38
relative to the central axis
31
of the drive shaft
18
and actuator unit
19
. Because of this angled positioning of the central axis
31
relative to the central axis
35
, these two central axes
31
,
35
intersect, this point of intersection giving the zero point of the eccentricity, thereby enabling zero delivery by the pumping units
20
.
Because the actuator unit
19
and the actuator eccentric
33
are of an axially slidable design, the different possible degrees of eccentricity can be used to produce different strokes of the pump pistons
24
of the pumping units
20
, enabling the delivery rate of the pumping units
20
to be varied accordingly.
By providing the actuator eccentric
33
in the design of an angled cylindrical body
34
and as a result of the angled contour of the bearing surface
37
relative to the central axis
31
, the piston shoes
71
can be positioned at an angle causing them to exert an axial reaction force on the actuator eccentric
33
. The self-generated pressure of the system or an external control pressure also acts on the plunger
54
. A force is generated from the surface of the plunger
54
which, combined with the reaction force generated by the angled positioning of the piston shoes
71
, pushes the actuator eccentric against the resilient forces of the return springs
68
until the forces reach equilibrium. The axial force needed to displace the actuator eccentric
33
can now be increased as a higher external control pressure is applied to the plunger
54
via the connecting piece
52
and the supply line
53
, enabling the actuator unit
19
to be pushed farther along the central axis
3
1
. The crucial factor here is that an actuator
26
for the actuator unit
19
co-operates with the pressure plate
58
in order to overcome the return force of the return springs
68
, the actuator
26
being provided as a plunger
54
mounted so as to be axially slidable in the threaded member
56
.
Looking more closely at the actuator unit
19
incorporating the actuator eccentric
33
, it may be seen that the actuator eccentric
33
has a stroke height
72
which can be freely selected on the basis of an axial displacement of the actuator unit
19
or actuator eccentric
33
. This stroke height
72
corresponds to a piston stroke
73
of the pump piston
24
, demonstrating how the degree of eccentricity of the actuator eccentric
33
and the stroke height
72
of the pump piston
24
depend one on the other.
As also illustrated, the central axis
35
of the actuator eccentric
33
, provided here as an angled cylindrical body
34
, extends at an acute angle
38
and intersects the central axis
31
of the drive shaft
18
and the actuator unit
19
at a zero point
74
. The diagram in
FIG. 4
shows the maximum delivery rate of the pumping units
20
. By displacing the actuator unit
19
in the direction of the drive unit
3
, the eccentricity of the angled cylindrical body
34
relative to the central axis
31
is reduced. As a result, the piston stroke
73
of the pump pistons
24
with their piston shoes
71
along the central axis
75
reduces and the delivery rate is reduced. The actuator unit
19
can be pushed by the maximum displacement path
76
along its central axis
31
, producing the desired structure dependent minimum delivery rate. The layout may be such that a displacement path
76
is selected to be of a size such that the central axis
75
of the piston pumps
24
overlaps the intersection point
74
with the central axes
31
and
35
. In this position, the radial piston pump
1
delivers a zero quantity when the actuator unit
19
or the actuator eccentric
33
is rotated.
As may also be seen from
FIG. 4
, the bearing seat
69
is of a circumferential design so that it is displaced through the same rotary motion as the actuator unit
19
, thereby assuming the bearing function for the return springs
68
. The bearing seat
69
simultaneously restricts the displacement path
76
. In principle, it should be pointed out that these return springs
68
stabilise the actuator unit
19
in the position illustrated in FIG.
4
and if there is any axial displacement of the actuator unit
19
in the direction of the drive unit
3
, it must be possible to overcome the retaining force of these return springs
68
by means of the pressure plate
58
and the plunger
54
operated by the pressure medium.
As may also be seen from the diagram, a radial bearing
77
is provided on the return springs
68
or the bearing seat
69
in the direction towards the drive unit
3
. In order to prevent leakages, the peripheral seal
78
is provided between the flanged plate
17
and the drive unit
3
as well as a peripheral seal
85
between the flanged plate
17
and the housing component
16
. Depending on the type of drive unit, it may be necessary to provide a washer—not illustrated here—on the drive shaft
18
.
FIGS. 5 and 6
illustrate another embodiment of the pumping system
2
proposed by the invention.
In this embodiment, the delivery volume of the pumping units
20
is automatically regulated to produce a predetermined system pressure without any external control. The same reference numbers will be used for these drawings as those used for components already described above in relation to the other drawings. Illustrated here are the housing component
16
with the pumping units
20
and the drive shaft
1
8
with the actuator unit
19
or actuator eccentric
33
. As may be seen from this diagram, the actuator unit
19
with its actuator eccentric
33
is pushed axially onto the drive shaft
18
so that a central axis of the actuator unit
19
is merged with the central axis of the drive shaft
18
. As a result of this arrangement, the actuator unit
19
incorporating the actuator eccentric
33
is mounted on the drive shaft
18
so that so that it can be displaced axially along the central axes
31
of the actuator unit
19
and the drive shaft
18
one top of the other. In order to transmit the rotary motion from the drive shaft
18
to the actuator unit
19
incorporating the actuator eccentric
33
, a biasing spring
47
is inserted in the recess
32
in the mounting bore
30
and in a recess
46
in the drive shaft
18
corresponding to the recess
32
. This biasing spring
47
is used purely to transmit the rotary motion of the drive shaft
18
to the actuator unit
19
but permits an axial displacement of the actuator unit
19
incorporating the actuator eccentric
33
along the central axis
31
in an axial direction.
The return springs
68
are supported by internally disposed pins
80
, designed to prevent any deformation or kinking in the return springs
68
if subjected to high stress.
Arranged on the drive shaft
18
at the end region
79
of the actuator unit
19
remote from the drive unit
3
is a casing
81
, forming a circumferential flange and an end stop for the axial displacement of the actuator unit
19
in its position at a distance from the drive unit
3
. A base
82
of the stop mechanism
81
projects into the mounting bore
30
of the actuator unit
19
and its end face
83
facing the drive shaft
18
bears on the end face
48
thereof. A flank
84
of the stop mechanism
81
has a larger diameter
85
than the end-to-end bore
30
of the actuator unit
19
. As a result of this layout, the flank
84
of the stop mechanism
81
lies against an end face
86
of the actuator unit
19
, thereby securing the actuator unit
19
in the position it assumes due to the return springs
68
. The stop mechanism
81
has an end-to-end bore
87
, through which a screw
88
is inserted, thereby securing the stop mechanism
81
. A blind bore
89
is provided in the end face
48
of the drive shaft
18
, into which the screw
88
is screwed, thereby securing the stop mechanism
81
on the drive shaft
18
. The stop mechanism
81
also prevents any axial displacement of the biasing spring
47
, so that the actuator unit
19
is locked onto the drive shaft
18
in rotation.
The delivery volume is adjusted by axially displacing the actuator unit
19
along the drive shaft
18
as follows.
In the illustration provided here and when the drive shaft
18
is rotated, a maximum delivery volume is reached because in this position the actuator eccentric
33
exhibits the maximum eccentric stroke and the pump pistons
24
of the pumping units
20
in turn have the biggest piston stroke
73
. As the pump pistons
24
are retracted from the pumping units
20
, the surrounding medium
10
is sucked in , compressed by the returning pump pistons
24
and discharged via a non-return valve in the pumping unit
20
to a pressure system or a consumer.
The operating principle of the pumping system
2
will now be described below with reference to
FIGS. 5 and 6
, this operating principle clearly also being applicable to
FIGS. 1
to
4
described earlier.
It should be pointed out that the desired axial displacement of the actuator unit
19
is achieved by the effect of the force applied by the pump pistons
24
and the piston shoes
71
. By means of the pumping units
20
disposed radially around the actuator unit
19
, a specific delivery rate is obtained as a working pressure gradually builds up in the pressure system and the consumers. As the requisite working pressure builds up within the pressure system, the pressure on the pump pistons
24
increases. This pressure is transmitted across the piston shoes
71
to the actuator unit
19
or the actuator eccentric
33
or on the bearing surface
37
thereof extending at an angle to the central axis
31
of the actuator unit
19
, producing a perpendicular compressive force
90
acting on the bearing surface
37
. This compressive force
90
is now broken by a parallelogram of forces into a radially acting force component
91
and an axially acting force component
92
.
If the compressive force
90
increases further due to a rising consumption pressure, the axial force component
92
becomes so high that it causes the actuator eccentric
33
or the actuator unit
19
to be displaced in an axial direction and in the direction of the force component
92
due to the angled disposition of the bearing surface
37
. In principle, displacement of the actuator unit
19
in the axial direction occurs when the axially acting for component
92
exceeds the return force of the returns springs
68
acting against it. As a result of this displacement, the piston stroke
73
is reduced, reducing the delivery rate of the radial piston pump
1
or the pumping units
20
accordingly. The displacement of the actuator unit
19
or the actuator eccentric
33
persists until an equilibrium is reached between the resilient force of the return springs
68
and the axially acting force component
92
of the compressive force
90
. Accordingly, the smaller the piston stroke
73
becomes, the more the delivery rate of the radial piston pump
1
decreases until only the line losses of a consumer or of the pressure system are being covered.
If the system pressure is then reduced or if a consumer is placed out of action, the compressive force
90
on the pump pistons
24
or on the bearing surface
37
of the actuator eccentric
33
decreases. The axial force component
92
of the compressive force
90
also decreases as a result and falls in terms of value below the return force of the return springs
68
. The result of this layout is that if a higher delivery rate is required, the actuator unit
19
or the actuator eccentric
33
is returned to its original position and the pump pistons
24
returned to their largest possible piston stroke
73
.
One particular advantage of this arrangement is that, due to the stepless displacement of the actuator unit
19
, the delivery rate can be adjusted to suit any requirements so that the radial piston pump
1
operates in accordance with performance characteristics which rise and fall relatively uniformly. Furthermore, different pressure ranges can be set for the radial piston pump
1
by adjusting the spring force of the return springs
68
.
Finally, for the sake of completeness, it should be reiterated that the compressive force
90
acts perpendicularly on the angularly disposed bearing surface, resulting in a force component
92
which acts axially on the actuator unit
19
or the actuator eccentric
33
, so that the compressive force
90
acting via the pump pistons
24
and hence the axially acting force component
92
increase depending on the delivery volume due to an increase in the system pressure. Furthermore, as the axially acting force component exceeds the opposing return force of the return springs
68
, displacement of the actuator unit
19
is initiated, this displacement of the actuator unit
19
causing a reduction in the piston stroke
73
of the pump pistons
24
of the pumping units
20
via the actuator eccentric
33
and hence also a decrease in the delivery volume. This displacement of the actuator unit
19
in the axial direction continues until an equilibrium is reached between the return force of the return springs
68
and the axially acting force component
92
of the compressive force
90
, thereby producing a uniformly rising or falling output curve of the radial piston pump
1
due to the stepless displacement of the actuator unit
19
via the actuator eccentric
33
.
For the sake of good order, it should finally be pointed out that in order to provide a clearer understanding of the structure of the radial piston pump
1
, it and its constituent parts have been illustrated out of scale to a certain extent and/or on an enlarged and/or reduced scale.
The independent solutions to the task proposed by the invention can be found in the description.
Above all, the subject matter of the individual embodiments illustrated in
FIGS. 1
,
2
;
3
;
4
;
5
,
6
can be construed as independent solutions proposed by the invention. The related tasks and solutions can be found in the detailed descriptions relating to these drawings.
LIST OF REFERENCE NUMBERS
1
Radical piston pump
2
Pumping system
3
Drive unit
4
Motor
5
Control System
6
Base plate
7
Foot
8
Standing surface
9
Supply container
10
Medium
11
Inlet opening
12
Liquid level indicator
13
Screw
14
Outlet Opening
15
Flange
16
Housing component
17
Flanged plate
18
Drive shaft
19
Actuator unit
20
Pumping units
21
Pump housing
22
Bore
23
Spring
24
Pump piston
25
Piston shoe
26
Actuator
27
Pump outlet
28
Bore
29
Outlet
30
Mounting bore
31
Central axis
32
Recess
33
Actuator eccentric
34
Cylindrical body
35
Central axis
36
Lateral surface
37
Bearing surface
38
Angle
39
Mounting bore
40
Length
41
Total length
42
Recess
43
Bore
44
Diameter
45
Diameter
46
Recess
47
Biasing spring
48
End face
49
Screw
50
Housing
51
End region
52
Connecting piece
53
Supply line
54
Plunger
55
Central axis
56
Threaded member
57
Seal
58
Pressure plate
59
End face
60
Internal face
61
Projection
62
Diameter
63
Flank
64
Thrust Bearing
65
Guide pin
66
Bore
67
Central axis
68
Return spring
69
Bearing seat
70
Distance
71
Piston shoe
72
Stroke height
73
Piston stroke
74
Zero point
75
Central axis
76
Displacement path
77
Radical bearing
78
Seal
79
End region
80
Pin
81
Stop mechanism
82
Base
83
End face
84
Flank
85
Diameter
86
End face
87
End-to-end bore
88
Screw
89
Blind bore
90
Compressive force
91
Force component
92
Force component
Claims
- 1. A radial piston pump comprising(a) a plate-shaped housing having bores for conveying a fluid medium, (b) a drive unit joined to the housing at one side thereof and having a drive shaft projecting through the housing, (c) a storage container for the fluid medium fluid-tightly joined to the housing at a side thereof opposite to the one side, (c) pumping units comprising pump pistons arranged at the opposite side of the plate-shaped housing, the pump pistons circumferentially surrounding the drive shaft and being radially displaceable relative thereto, and (d) an eccentric actuator unit for radially displacing the pump pistons, the actuator unit having an axially extending bore receiving the drive shaft, being axially displaceably mounted on the drive shaft and keyed thereto for rotation therewith, and the actuator unit comprising (1) a cylindrical body having an axis inclined relative to the axis of the drive shaft and a like inclined surface bearing on the pump pistons.
- 2. The radial piston pump of claim 1, further comprising a biasing mechanism for displacing the actuator unit into an end position against a stop axially spaced from the housing, the biasing mechanism comprising return springs arranged in, and substantially parallel to, the axially extending actuator unit bore.
- 3. The radial piston pump of claim 2, further comprising an annular bearing seat supporting the return springs at ends thereof opposite the stop.
- 4. The radial piston pump of claim 3, wherein the bearing seat is a ring surrounding a cylindrical portion of the actuator unit axially projecting from the cylindrical body having an inclined axis, further comprising a radial bearing supporting the bearing ring and bearing the cylindrical portion of the actuator unit.
- 5. The radial piston pump of claim 1, further comprising a spring coupling the actuator unit to the drive shaft for locking the actuator unit against rotation relative to the drive shaft.
- 6. The radial piston pump of claim 1, further comprising a casing circumferentially surrounding an end of the actuator unit remote from the drive unit, and an actuator arranged in the casing.
- 7. The radial piston pump of claim 6, further comprising a thrust bearing arranged between a pressure plate of the actuator and an end face of a recess of the actuator unit.
- 8. The radial piston pump of claim 7, further comprising a biasing mechanism for displacing the actuator unit into an end position against the pressure plate of the actuator, and the actuator comprises a pressure medium activated plunger exerting an axial bias force opposite the bias force exerted by the biasing mechanism.
- 9. The radial piston pump of claim 8, wherein the plunger is connected to the pressure plate by a press-fit to prevent displacement.
- 10. The radial piston pump of claim 1, wherein the pumping units have outlets communicating with each other by bores in the plate-shaped housing, the bores constituting pressure lines for the fluid medium.
- 11. The radial piston pump of claim 1, further comprising a flanged bearing plate affixing the plate-shaped housing and a pump housing for the pump pistons arranged at the opposite side thereof to the drive unit.
- 12. The radial piston pump of claim 1, wherein the pump pistons carry piston shoes in contact with the inclined bearing surface of the cylindrical body of the actuator unit.
- 13. The radial piston pump of claim 12, wherein the piston shoes are universally pivotally mounted on the pumping pistons.
- 14. The radial piston pump of claim 1, wherein the actuator unit is axially displaceable along a displacement path between end positions wherein the bearing surface of the cylindrical body has a zero eccentricity and a maximum eccentricity.
- 15. The radial piston pump of claim 14, wherein the displacement path has a length of 8 mm to 30 mm.
- 16. The radial piston pump of claim 15, wherein the length is about 15 mm.
- 17. The radial piston pump of claim 1, further comprising means for exerting a perpendicular force on the bearing surface of the cylindrical body of the actuator unit, resulting in a force component acting axially on the actuator unit.
- 18. The radial piston pump of claim 1, wherein the axis of the drive shaft and the axis of the cylindrical body enclose an angle of approximately 5° to 15°.
- 19. The radial piston pump of claim 18, wherein the angle is about 10°.
- 20. The radial piston pump of claim 1, wherein the bearing surface of the cylindrical body of the actuator unit has a maximum eccentricity of about 6 mm.
Priority Claims (1)
Number |
Date |
Country |
Kind |
338/98 U |
May 1998 |
AT |
|
PCT Information
Filing Document |
Filing Date |
Country |
Kind |
PCT/AT99/00125 |
|
WO |
00 |
Publishing Document |
Publishing Date |
Country |
Kind |
WO99/61797 |
12/2/1999 |
WO |
A |
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Foreign Referenced Citations (7)
Number |
Date |
Country |
543934 |
Jan 1932 |
DE |
11 12 431 |
Aug 1961 |
DE |
41 32 456 |
Apr 1993 |
DE |
841996 |
Jun 1939 |
FR |
930884 |
Sep 1947 |
FR |
2321608 |
Mar 1977 |
FR |
1149273 |
Apr 1969 |
GB |