U.S. patent application number 14/351790 was filed with the patent office on 2014-09-18 for controllable coolant pump having a fluidic actuator.
This patent application is currently assigned to SCHAEFFLER TECHNOLOGIES AG & CO. KG. The applicant listed for this patent is Klaus Hahn, Andreas Strauss, Michael Weiss. Invention is credited to Klaus Hahn, Andreas Strauss, Michael Weiss.
Application Number | 20140271267 14/351790 |
Document ID | / |
Family ID | 46639520 |
Filed Date | 2014-09-18 |
United States Patent
Application |
20140271267 |
Kind Code |
A1 |
Weiss; Michael ; et
al. |
September 18, 2014 |
CONTROLLABLE COOLANT PUMP HAVING A FLUIDIC ACTUATOR
Abstract
A controllable coolant pump for a cooling circuit of an internal
combustion engine having a pump housing with an inner bore, a shaft
drivable via a pulley mounted rotatably via a first bearing and a
second bearing, wherein the shaft is configured at least partially
as a hollow shaft and has a longitudinal axis, wherein a rotor is
fastened to one end of the shaft, which rotor has an idler pulley
and vanes which project into a suction chamber to suck water via a
suction connector of the pump housing into the suction chamber to
an annular channel of the pump housing, wherein the idler pulley
can be displaced axially via a push rod connected to an actuator.
The fluidic actuator has a first pressure chamber and a second
pressure chamber. The weight and the installation space requirement
of the controllable coolant pump can be reduced.
Inventors: |
Weiss; Michael;
(Herzogenaurach, DE) ; Hahn; Klaus;
(Obereichenbach, DE) ; Strauss; Andreas;
(Forchheim, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Weiss; Michael
Hahn; Klaus
Strauss; Andreas |
Herzogenaurach
Obereichenbach
Forchheim |
|
DE
DE
DE |
|
|
Assignee: |
SCHAEFFLER TECHNOLOGIES AG &
CO. KG
Herzogenaurach
DE
|
Family ID: |
46639520 |
Appl. No.: |
14/351790 |
Filed: |
August 9, 2012 |
PCT Filed: |
August 9, 2012 |
PCT NO: |
PCT/EP2012/065578 |
371 Date: |
April 14, 2014 |
Current U.S.
Class: |
417/364 |
Current CPC
Class: |
F01P 7/16 20130101; F04B
35/002 20130101; F04D 15/0038 20130101; F01P 2007/143 20130101;
F05D 2270/64 20130101 |
Class at
Publication: |
417/364 |
International
Class: |
F04B 35/00 20060101
F04B035/00 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 15, 2011 |
DE |
10 2011 088 674.5 |
Claims
1 to 9. (canceled)
10. A controllable coolant pump for a cooling circuit of an
internal combustion engine, comprising: a pump housing having an
inner bore; a shaft in the inner bore drivable by a drive wheel and
rotatably supported by a first bearing and a second bearing, the
shaft being at least partially designed as a hollow shaft and
having a longitudinal axis; a rotor fastened to the one end of the
shaft and having vanes projecting into a suction chamber and an
idler pulley, rotation of the rotor permitting water to be sucked
water into the suction chamber via an intake connection of the pump
housing and to be delivered to an annular channel of the pump
housing via the vanes, the idler pulley being axially movable via a
push rod connected to an actuator; the actuator forming a fluidic
actuator having a first fluid pressure chamber and a second fluid
pressure chamber.
11. The controllable coolant pump as recited in claim 10 further
comprising an annular first seal, an annular second seal located at
an axial distance therefrom and a movable sealing ring situated
between the first seal and the second seal, and provided in the
inner bore, the first pressure chamber being provided between the
first seal and the sealing ring, and the second pressure chamber
being provided between the sealing ring and the second seal.
12. The controllable coolant pump as recited in claim 11 wherein
the push rod is situated in the shaft and has a transmission
element contacting the sealing ring through at least one opening
provided in the shaft.
13. The controllable coolant pump as recited in claim 10 wherein
the push rod has a push rod shoulder on a first end situated within
the shaft, and a first shaft shoulder is provided within the shaft,
through which the push rod protrudes, an annular, variable first
pressure chamber being provided between the push rod shoulder, the
first shaft shoulder, the push rod and the shaft.
14. The controllable coolant pump as recited in claim 10 further
comprising an actuator housing having a recess and a cover to at
least partially accommodate the push rod in the recess, the
actuator housing being situated on the side of the drive wheel
facing away from the pump housing, the first pressure chamber being
provided in the actuator housing with the aid of the push rod and
the second pressure chamber being provided with the aid of the push
rod and the cover.
15. The controllable coolant pump as recited in claim 10 further
comprising at least one first end stop for limiting the axial
movement of the push rod provided on the shaft or the actuator
housing.
16. The controllable coolant pump as recited in claim 10 wherein
the pump housing, the actuator housing or the hollow shaft have at
least one fluid-permeable first bore to the first pressure chamber
and a second bore to the second pressure chamber for supplying
and/or discharging the fluid.
17. The controllable coolant pump as recited in claim 10 further
comprising a spring for actuating the push rod, the spring being
situated between the push rod and the shaft or the actuator housing
or the cover.
18. The controllable coolant pump as recited in claim 10 further
comprising a sensor element for detecting a position of the push
rod.
Description
[0001] The present invention relates to a controllable coolant
pump, in particular for an internal combustion engine, having a
fluidic actuator.
BACKGROUND
[0002] Internal combustion engines are usually water-cooled
engines, in which, with the aid of a coolant pump in a closed
circuit, cooling water is pumped through cooling channels in the
area of the cylinders for cooling the internal combustion engine
and subsequently conveyed to an air/water cooler, where the heated
water is cooled again with the aid of the air stream. The coolant
pump needed for circulating the water is usually connected to a
drive pulley of the crankshaft of the internal combustion engine
via a driving means. The direct coupling between the coolant pump
and the crankshaft establishes a dependency of the rotational speed
of the pump on the rotational speed of the internal combustion
engine, so that, in modern internal combustion engines,
controllable coolant pumps are frequently used whose delivered
volume flow may be adapted according to the demand for coolant.
[0003] A controllable coolant pump for a cooling circuit of an
internal combustion engine, including a pump housing, is known from
DE 10 2008 046 424 A1, in which a hollow shaft, drivable by a belt
pulley, is supported, to one end of which a rotor is fastened,
which has vanes extending into a suction chamber and which is
fixedly connected to a cover disk via axial bars, it being
possible, due to the rotation of the rotor together with the cover
disk, to suck water into the suction chamber via an intake
connection of the pump housing and to deliver it to an annular
channel of the pump housing via the vanes, an idler pulley which
has a contour corresponding to the rotor being situated between the
rotor and the cover disk, the idler pulley being guided via the
axial bars and being axially movable with the aid of a piston
placed within the hollow shaft, using a final control unit.
[0004] The disadvantage of a configuration of this type is that
controlling the coolant flow with the aid of the piston and the
final control unit makes for a heavy weight and requires a great
deal of installation space.
SUMMARY OF THE INVENTION
[0005] It is an object of the present invention to provide a
controllable coolant pump for a cooling circuit of an internal
combustion engine, which has a reduced weight and requires less
installation space.
[0006] The present invention provides a controllable coolant pump
for a cooling circuit of an internal combustion engine which
includes a pump housing having an inner bore, in which a shaft
which is drivable by a drive wheel is rotatably supported by a
first bearing and a second bearing, the shaft being at least
partially designed as a hollow shaft and having a longitudinal
axis, a rotor being fastened to the one end of the shaft and having
vanes and an idler pulley which extend into a suction chamber, it
being possible, due to the rotation of the rotor, to suck water
into the suction chamber via an intake connection of the pump
housing and to deliver it to an annular chamber of the pump housing
via the vanes, the idler pulley being axially movable via a push
rod connected to an actuator. According to the present invention,
the actuator forms a fluidic actuator, the fluidic actuator having
a first pressure chamber to which a pressurized fluid may be
applied, and a second pressure chamber to which a pressurized fluid
may be applied.
[0007] The controllable coolant pump is drivable via a drive wheel
which may be connected to the shaft on an end opposite the drive
wheel. The rotor may have vanes extending into a suction chamber,
it being possible, due to the rotation of the rotor to suck cooling
water into the suction chamber via an intake connection of the pump
housing and to deliver it to an annular channel of the pump housing
via the vanes. The idler pulley may be axially moved with the aid
of a push rod which may be situated coaxially to and partially
within the shaft, in particular the hollow shaft, the delivery
volume of the suction chamber of the coolant pump being variable.
In a first position of the push rod, the delivery volume and the
coolant flow of the cooling water pump may reach a maximum, while
in a second position of the push rod, the delivery volume and the
coolant flow of the cooling water pump may reach a minimum. The
pump housing of the coolant pump has an inner bore, in which a
first bearing and a second bearing, for example a first ball
bearing and a second ball bearing, are situated at an axial
distance from each other, the drivable shaft being rotatably
supported in the first bearing and in the second bearing. The shaft
may be designed, at least in part, in the form of a hollow shaft,
the portion of the shaft designed as a hollow shaft being designed
in the form of a bore or a blind hole. The shaft may also be
designed in the form of a hollow shaft, the hollow shaft being able
to have areas having different inner diameters, for example to
accommodate a push rod, in particular a push rod having different
diameters. The idler pulley is connected to the push rod, via which
the idler pulley is movable in the axial direction due to an axial
movement of the push rod. The push rod may be situated coaxially to
the shaft, it being possible to situate the push rod at least
partially within the shaft, in particular the hollow shaft. The
push rod is displaceable in the axial direction by a fluidic
actuator which is actuatable, for example, by a liquid or a gas.
The fluidic actuator has a first pressure chamber and a second
pressure chamber, it being possible to apply a pressurized fluid to
the first pressure chamber and to the second pressure chamber.
[0008] The pressure may be an underpressure or an overpressure in
relation to an ambient pressure. The first pressure chamber and the
second pressure chamber may be situated coaxially to the
longitudinal axis of the shaft, in particular within the pump
housing, in particular within the inner bore of the pump housing.
The pressure acting upon the first and the second pressure chambers
may be controlled, for example by a four/two-way valve. Due to the
fluidic actuator, a continuous, in particular hydraulic or
pneumatic, control of the water pump for the cooling circuit of the
internal combustion engine is possible. In particular, the control
of the coolant pump may take place continuously. Moreover, the
weight and the installation space requirements of the controllable
coolant pump may be reduced by using a fluidic actuator. The energy
demand of the controllable coolant pump may furthermore be
reduced.
[0009] In one preferred embodiment, an annular first seal, an
annular second seal located at an axial distance therefrom and a
movable sealing ring situated between the first seal and the second
seal are provided in the inner bore, a first pressure chamber being
provided between the first seal and the sealing ring, and a second
pressure chamber being provided between the sealing ring and the
second seal. The annular first seal may be situated and supported,
for example, on the first bearing, and the annual second seal may
be situated and supported, for example, on the second bearing
opposite the first seal. A sealing ring, which is movably situated
and provided in the axial direction between the first seal and the
second seal, is situated between the first seal and the second
seal. An annular first pressure chamber is provided between the
first seal and the sealing ring, the first pressure chamber having
a variable volume, and an annular second pressure chamber, which is
also variable in its volume size, being provided between the second
seal and the sealing ring. The total volume of the first pressure
chamber and the second pressure chamber remains essentially
constant, an increase in the size of the first pressure chamber
being able to essentially correspond to a decrease in the size of
the second pressure chamber. The first pressure chamber and the
second pressure chamber have an essentially annular shape, it being
possible to provide the first and second pressure chambers between
the pump housing and the shaft in the radial direction. The first
and second pressure chambers essentially have pressure surfaces of
essentially the same size, in particular on the sealing ring. The
sealing ring is movable in the axial direction by a change in
pressure in the first pressure chamber and/or the second pressure
chamber, with a corresponding change in volume. The axial movement
of the sealing ring is transmittable to the push rod, whereby a
change in the position, in particular in the axial direction of the
idler pulley, is achievable. The sealing ring may be displaced in
the axial direction in the inner bore, in the manner of a piston,
whereby a continuous, in particular hydraulic or pneumatic, control
of the coolant pump, in particular the idler pulley of the coolant
pump, may be facilitated.
[0010] The push rod situated in the shaft preferably has a
transmission element, which contacts the sealing ring through at
least one opening provided in the shaft. The push rod situated
within the shaft may have a transmission element, with the aid of
which the push rod may be connected to the sealing ring, the
movement of the sealing ring, at least the movement of the sealing
ring in an axial direction, being transmittable to the push rod.
The transmission element may be designed in the form of a cross
pin, which may protrude essentially perpendicularly through the
push rod or be situated thereon, and which rests against the
sealing ring at least on one side. The transmission element may be
fixedly connected to the sealing ring, whereby an axial movement of
the sealing ring may be transmittable to the push rod in two axial
directions. To feed the transmission element through the shaft, in
particular the hollow shaft, the shaft may have at least one
opening, for example in the form of an elongated hole. The sealing
ring may have an extension in the axial direction, which
facilitates a covering of the opening in the shaft, as well as a
fluid-tight sealing of the at least one opening with respect to the
first and the second pressure chambers. A structurally simple
transmission of an axial movement of the sealing ring to the push
rod may be ensured with the aid of the transmission element.
[0011] It is preferred that the push rod has a push rod shoulder on
a first end situated within the shaft, and a first shaft shoulder
is provided within the shaft, through which the push rod protrudes,
an annular, variable first pressure chamber being provided between
the push rod shoulder, the first shaft shoulder, the push rod and
the shaft. The push rod shoulder of the push rod may be provided
within the hollow shaft, for example in an annular or disk-shaped
manner, the diameter of the push rod being able to be significantly
smaller than the diameter of the push rod shoulder, which may
essentially correspond to the inner diameter of the hollow shaft.
The first shaft shoulder is provided at an axial distance from the
push rod shoulder and may have an annular or disk-shaped design, in
particular including a push rod lead-through for axial lead-
through of the push rod. A first pressure chamber, which is
delimited in the radial direction by the inner wall of the hollow
shaft and the push rod, is provided between the push rod shoulder
and the first shaft shoulder in the axial direction. A second shaft
shoulder may be provided within the shaft, in particular the hollow
shaft, on a side of the push rod shoulder facing away from the
first shaft shoulder. The second shaft shoulder may be designed,
for example, in the form of a solid continuation of the shaft or in
the form of an insert within the hollow shaft. A second pressure
chamber, which is provided in the radial direction by the inner
wall of the hollow shaft and the push rod, may be provided between
the push rod shoulder and the second shaft shoulder in the axial
direction. The second shaft shoulder, in particular in the form of
a solid shaft, may have a push rod lead-through for leading through
the push rod, for example for contacting the push rod with the aid
of the idler pulley. With the aid of the push rod lead-throughs, it
may be ensured, in particular, that the pressure surfaces of the
first pressure chamber and the second pressure chamber are
essentially of the same size, in particular on the push rod
shoulder. The push rod shoulder may be situated within the hollow
shaft between the first shaft shoulder and the second shaft
shoulder in a way which permits movement in the axial direction in
the manner of a piston, valve or slide valve. In particular the
push rod shoulder may be situated in a hollow shaft which
essentially functions like a cylinder in a way which permits
movement in the axial direction in a piston-like manner. A first
pressure chamber and/or a second pressure chamber may be provided
within the hollow shaft for axial displacement of the push rod, in
particular the push rod shoulder. An axial movement of the push rod
shoulder may be achievable by a change in pressure in the first
pressure chamber and/or in the second pressure chamber, it being
possible to provide the first pressure chamber and the second
pressure chamber within the hollow shaft and to situate them
coaxially with respect to each other.
[0012] In one preferred embodiment of the present invention, an
actuator housing having a recess and a cover is provided to at
least partially accommodate the push rod in the recess, the
actuator housing being situated on the side of the drive wheel
facing away from the pump housing, a first pressure chamber being
provided in the actuator housing with the aid of the push rod and a
second pressure chamber being provided with the aid of the push rod
and the cover. The recess of the actuator housing may be designed,
for example, in the form of a blind bore hole which may be covered
by a cover, the cover being able to have a push rod lead-through.
The push rod may have a first push rod shoulder, which may be
situated within the recess of the actuator housing, the diameter of
the push rod shoulder being able to essentially correspond to the
inner diameter of the recess of the actuator housing, the diameter
of the push rod being able to be significantly smaller than the
diameter of the first, for example disk-shaped, push rod shoulder.
A first pressure chamber, which is delimited in the radial
direction by the push rod and the inner wall and the recess of the
actuator housing, is provided between the first push rod shoulder
and the actuator housing, a second pressure chamber is delimited
between the first push rod shoulder and the cover in the axial
direction, which is delimited in the radial direction by the inner
wall of the recess of the actuator housing and the push rod. Within
the recess of the actuator housing, the push rod, in particular the
push rod shoulder, is movably situated and provided in the manner
of a piston by a change in pressure in the first pressure chamber
and in the second pressure chamber. Due to the axial movement of
the push rod shoulder, the movement may be transmitted to the idler
pulley via the push rod, whereby the delivery volume, and thus the
coolant flow of the coolant pump, is controllable. Due to the
provision of the fluidic actuator in the actuator housing, which is
situated on the side of the drive wheel facing away from the pump
housing, the actuator may be transferred out of the pump housing,
whereby the installation space of the pump housing of the coolant
pump may be optimized, in particular in the axial direction.
[0013] In particular, at least one first end stop for limiting the
axial movement of the push rod is provided on the shaft and/or the
actuator housing. The first end stop may be provided on the hollow
shaft and/or the actuator housing, the first end stop being able to
limit the movement, in particular in the axial direction of the
push rod, in particular the push rod shoulder. In addition to the
first end stop, a second end stop may be provided, situated at an
axial distance from the first end stop. The first end stop and the
second end stop may have, for example, an annular or disk-shaped
design or be in the form of a shoulder which is provided within the
hollow shaft, oriented radially to the inside. An annular first
and/or second end stop, for example in the form of a snap ring, may
be accommodated in a groove within the inner wall of the hollow
shaft. The first and second end stops may be situated in such a way
that the push rod, in particular the first and/or the second push
rod shoulder(s), is displaceably situated in the axial direction
between the first end stop and the second end stop. Due to the
design of the first and/or second end stop(s), the movement of the
push rod in the axial direction may be limited. It may also be
ensured that the first and/or the second pressure chamber(s)
has/have a minimum volume.
[0014] The pump housing, the actuator housing and/or the hollow
shaft preferably has/have at least one fluid-permeable first bore
to the first pressure chamber and a second bore to the second
pressure chamber for supplying and/or discharging the fluid. The
first bore and/or the second bore facilitate(s) the application of
pressure to the first and/or the second pressure chamber(s) by a
fluid. The first and/or second pressure bore(s) may extend through
the pump housing and the shaft, in particular a wall of the hollow
shaft, up to the first and/or the second pressure chamber(s). The
pump housing may have a housing shoulder which may be situated
within the inner bore, in particular in the axial direction between
the first and second bearings, it being possible to provide the
housing shoulder radially to the inside and to contact the shaft,
in particular the hollow shaft, radially on the outside. Due to the
housing shoulder, which extends radially to the inside and contacts
the shaft, it is possible to guide the first bore and/or the second
bore(s) through the pump housing up to the shaft, in particular the
hollow shaft, and to lead the first bore and/or the second bore(s)
to the first pressure chamber and/or the second pressure chamber in
a fluid-permeable manner. Pressure may thus be applied to the first
pressure chamber and the second pressure chamber, due to a simple
construction.
[0015] A spring element for actuating the push rod is particularly
preferably provided, the spring element being situated between the
push rod and the shaft or the actuator housing or the cover. The
spring element may be designed in the form of a tension spring or a
pressure spring. The spring element may be situated in such a way
that an axial displacement of the push rod, in particular the push
rod shoulder, for example to reduce the volume flow of the coolant
pump, may be directed against the direction of force of the spring
element, whereby a return of the push rod, in particular of the
push rod shoulder, for example to a first position having a maximum
coolant delivery flow, may be ensured if the fluidic actuator
fails. If a single first pressure chamber is used, which acts
against the force of the spring element, the structural complexity
of the fluidic actuator may also be further reduced.
[0016] In one preferred embodiment of the present invention, a
sensor element is provided for detecting the position of the push
rod. The sensor element may be designed in the form of a
mechanical, opto-electronic or electromagnetic sensor. The sensor
element may be situated on the sealing ring, the push rod and/or
the push rod shoulder, for example in the pump housing and/or the
actuator housing. The sensor element may detect an axial
displacement and/or position in the axial direction of the sealing
ring, the push rod and/or the push rod shoulder. In particular, the
sensor element may detect the absolute position in the axial
direction of the sealing ring, the push rod and/or the push rod
shoulder. Due to the sensor element, the actual position of the
sealing ring, the push rod and/or the push rod shoulder may be
detected, in particular in the axial direction, whereby the
position of the idler pulley is ascertainable.
[0017] Due to the use of a controllable coolant pump according to
the present invention in an internal combustion engine, the weight
and the necessary installation space of the controllable coolant
pump, and in particular the internal combustion engine, may be
reduced.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] The present invention is explained below by way of example
on the basis of preferred exemplary embodiments, with reference to
the attached drawings.
[0019] FIG. 1 shows a schematic sectional view of a controllable
coolant pump according to the present invention;
[0020] FIG. 2 shows a schematic sectional view of a controllable
coolant pump according to the present invention, including a first
pressure chamber and a second pressure chamber within a hollow
shaft;
[0021] FIG. 3 shows a sectional view of a hollow shaft, including a
push rod and a first and a second pressure chamber;
[0022] FIG. 4a shows a schematic view or a sectional view of a push
rod in a first position on a first end stop;
[0023] FIG. 4b shows a schematic sectional view of a push rod
between a first and a second end stop;
[0024] FIG. 4c shows a schematic view of a controllable coolant
pump, including a pressurized second pressure chamber;
[0025] FIG. 5 shows a schematic sectional view of an actuator
housing, including a sensor element.
DETAILED DESCRIPTION
[0026] FIG. 1 shows a controllable coolant pump 10, which has a
pump housing 12, including an inner bore 14. A first bearing 16 is
situated within inner bore 14, and a second bearing 18 is situated
at an axial distance therefrom. A shaft 20 is rotatably situated in
first bearing 16 and second bearing 18 within inner bore 14 of pump
housing 12. Between first bearing 16 and second bearing 18, an
annular first seal 22 is situated on first bearing 16, and an
annular second seal 24 is situated on second bearing 18. First seal
22 and second seal 24 form an essentially fluid-impermeable seal in
the axial direction. A sealing ring 26, which is movably supported
in the axial direction between first seal 22 and second seal 24, is
situated between first bearing 16 and second bearing 18 and first
seal 22 and second seal 24. A first pressure chamber 28, which is
delimited in the radial direction by shaft 20 and pump housing 12,
is provided between first seal 22 and sealing ring 26 in the axial
direction. A second pressure chamber 30, which is delimited in the
radial direction by shaft 20 and pump housing 12, is provided
between second seal 24 and sealing ring 26 in the axial direction.
An axial movement of sealing ring 26 is transmittable via a
transmission element 32, which is connected to a push rod 34
situated within shaft 20. Transmission element 32 is situated
essentially perpendicularly to push rod 34 and connected thereto,
transmission element 32 protruding through shaft 20 through
openings 36 and contacting sealing ring 26 on one side.
Transmission element 32 may be fixedly connected to sealing ring
26. A pressurized fluid may be applied to first pressure chamber 28
via a first bore 38 in pump housing 12, and a pressurized fluid may
be applied to second pressure chamber 30 via a second bore 40 in
pump housing 12. Due to a change in pressure in first pressure
chamber 28 and/or second pressure chamber 30, an axial movement of
sealing ring 26 may be implemented, the axial movement of sealing
ring 26 being transmittable to push rod 34 via transmission element
32. Push rod 34 may be connected to an idler pulley (not
illustrated) of controllable coolant pump 10, whereby the volume
flow of coolant pump 10 may be controlled. A spring force may be
applied to push rod 34 by a spring element 42, which is situated on
the front of push rod 34 and is supported on the inside of shaft
20. A sensor element 44, which detects the position of sealing ring
26, is situated in pump housing 12.
[0027] FIG. 2 shows a controllable coolant pump 10, whose pump
housing 12 has a housing shoulder 46 between first bearing 16 and
second bearing 18, which extends radially to the inside and
contacts shaft 20 on the outside. First bore 38 extends through
pump housing 12, housing shoulder 46 and the wall of shaft 20,
which is at least partially designed as a hollow shaft, whereby a
pressurized fluid may be applied to first pressure chamber 28 and
second pressure chamber 30. First pressure chamber 28 is delimited
in the axial direction between a push rod shoulder 48 and a first
shaft shoulder 50, which is situated at an axial distance from push
rod shoulder 48. Push rod shoulder 48 is designed in the shape of a
disk which is provided on push rod 34. The diameter of push rod
shoulder 48 essentially corresponds to the inner diameter of shaft
20, which is at least partially designed as a hollow shaft. First
shaft shoulder 50 is designed in the form of a disk-shaped insert
in the area of shaft 20 designed as a hollow shaft and has a push
rod lead-through. Second pressure chamber 30 is provided in the
axial direction between push rod shoulder 48 and a second shaft
shoulder 52 situated on the side of push rod shoulder 48 facing
away from first shaft shoulder 50 and is delimited in the radial
direction by shaft 20 and push rod 34. A spring element 42 is
situated within second pressure chamber 30, with the aid of which
push rod 34, in particular push rod shoulder 48, may be displaced
in the axial direction into a defined position, for example a first
position having a maximum delivery volume, in the event of a
pressure drop. Sensor element 44 is situated on pump housing 12 in
such a way that sensor element 44 is able to contact push rod 34,
whereby the position of push rod 34 may be detected in the axial
direction.
[0028] FIG. 3 shows a shaft 20, which is at least partially
designed as a hollow shaft in the form of a blind bore hole, in
which push rod 34, including a first push rod shoulder 48, is
situated, push rod 34 being led through a first shaft shoulder 50
and a second shaft shoulder 52. First pressure chamber 28, to which
a pressurized fluid may be applied through a first bore 38, is
provided between first shaft shoulder 50 and push rod shoulder 48.
Second pressure chamber 30 is provided between push rod shoulder 48
and second shaft shoulder 52 in the form of the solid shaft
continuation, and a pressurized fluid may be applied thereto
through second bore 40. Spring element 42, which rests against and
is situated on push rod shoulder 48 and second shaft shoulder 52,
is situated in second pressure chamber 30. Shaft 20 has a first end
stop 54 and a second end stop 56 on the radial inside, push rod
shoulder 48 being displaceable between first end stop 54 and second
end stop 56 in the axial direction, the axial movement of push rod
shoulder 48, and thus of the push rod, being limited by first and
second end stops 54, 56.
[0029] FIG. 4a shows a push rod 34 having a push rod shoulder 48
within a shaft 20, a pressure being applied to first pressure
chamber 28 via first bore 38, the second opening or bore 40 of
second pressure chamber 30 being depressurized, for example
connected to a tank. Push rod 34 is shown in a first position, in
which controllable coolant pump 10 has its maximum delivery volume.
Push rod 34, in particular push rod section 48, rests against first
end stop 54. Due to the application of pressure to first pressure
chamber 28, push rod 34 may be displaced to the right in the axial
direction in the direction of second end stop 56, whereby the
position of the idler pulley (not illustrated) is variable, whereby
the delivery volume of coolant pump 10 is variable. FIG. 4b shows a
push rod 34, whose push rod section 48 is shown in a position
approximately between first end stop 54 and second end stop 56.
Spring element 42 is compressed with respect to the illustration in
FIG. 4a. A fluid is applied to first pressure chamber 28 and second
pressure chamber 30 through first bore 38 and second bore 40, the
pressure in first pressure chamber 28 essentially corresponding to
the pressure in second pressure chamber 30. Taking the force of
spring element 42 into account, a force equilibrium between first
and second pressure chambers 28, 30 may be set, whereby push rod 34
may be held in the particular position in a stationary manner. In
FIG. 4c, first pressure chamber 28 is depressurized via first bore
38, for example by connecting it to a tank. A pressurized fluid is
applied to second pressure chamber 30 through second bore 40, the
pressure being greater than the pressure, for example an ambient
pressure, acting in first pressure chamber 28, whereby push rod 34,
together with push rod shoulder 48, was moved in the axial
direction in the direction of first end stop 54, starting from the
position of push rod 34 illustrated in FIG. 4b. The force of spring
element 42 may act in the direction or against the direction of the
movement of push rod 34.
[0030] FIGS. 4a through 4c show, by way of example, a sequence of
switching operations for the fluidic actuator according to the
present invention, for example using a 4/2-way valve. First and
second pressure chambers 28, 30 are filled with a fluid. To leave a
basic position, for example the first position, of the push rod, a
fluid may be supplied to first pressure chamber 28 via first bore
38, it being possible to connect second bore 40 of second pressure
chamber 30 to a tank (not illustrated) or an outlet. The
pressurized fluid acts upon push rod shoulder 48 and displaces it
against the force of spring element 42 in the manner of a piston.
Once the desired position has been reached, both bores, first and
second bores 38, 40, may be connected to the pressure line. The
fluidic actuator maintains its set position, a control operation
being able to only compensate for leaks. If push rod 34 is
displaced in the direction of the basic position, first bore 38 may
be connected to the tank, pressure continuing to be applied to
second bore 40. If the pressure supply fails, push rod 34 may be
returned to the basic position with the aid of spring element
42.
[0031] FIG. 5 shows a controllable coolant pump 10 having an
actuator housing 58. Actuator housing 58 has a recess, in which
push rod 34, including push rod section 48, is situated in the
manner of a piston. The recess in actuator housing 58 is closed by
a cover 60. Actuator housing 58 and cover 60 have a lead-through
for push rod 34. First pressure chamber 28 is provided between
actuator housing 58 and push rod shoulder 48, and second pressure
chamber 30 is provided between push rod shoulder 48 and cover 60. A
spring element 42 is situated in second pressure chamber 30. A
pressurized fluid may be applied to first pressure chamber 28 via
first bore 38, and a pressurized fluid may be applied to second
pressure chamber 30 via second bore 40. Due to a pressure change in
first and/or second pressure chamber(s) 28, 30, a displacement of
push rod shoulder 48 and push rod 34 may be implemented in the
axial direction, whereby push rod 34 connected to the idler pulley
may cause a change in the volume flow of coolant pump 10. A sensor
element 44, which detects the axial position and/or movement of
push rod 34, is situated on actuator housing 58.
List of Reference Numerals
[0032] 10 Coolant pump
[0033] 12 Pump housing
[0034] 14 Inner bore
[0035] 16 First bearing
[0036] 18 Second bearing
[0037] 20 Shaft
[0038] 22 First seal
[0039] 24 Second seal
[0040] 26 Sealing ring
[0041] 28 First pressure chamber
[0042] 30 Second pressure chamber
[0043] 32 Transmission element
[0044] 34 Push rod
[0045] 36 Opening
[0046] 38 First bore
[0047] 40 Second bore
[0048] 42 Spring element
[0049] 44 Sensor element
[0050] 46 Housing shoulder
[0051] 48 Push rod shoulder
[0052] 50 First shaft shoulder
[0053] 52 Second shaft shoulder
[0054] 54 First end stop
[0055] 56 Second end stop
[0056] 58 Actuator housing
[0057] 60 Cover
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