LABYRINTHINE RADIAL PISTON-HYDRAULIC VARIABLE WATERPUMP ACTUATION SYSTEM

Abstract

A regulatable coolant pump of an internal combustion engine having a pump housing in which a pump shaft with an associated impeller is rotatably mounted. The impeller conveys a coolant from an inlet connection into an outlet of the coolant pump, a volume flow of the coolant pump being adjustable by a cover that externally surrounds the impeller at least in some regions and is displaceable by a pressure medium. The cover is moved by an actuator including a solenoid in contact with a piston that is moveable into a piston pressure chamber in order to generate high pressure pulses of a pressure medium that are transmitted to a plunger chamber where they act on a plunger connected to the cover. Upon actuation of the solenoid, the cover is moved by the pressure medium acting on the plunger to an actuated end position.

Description

BACKGROUND

The present invention relates to a regulatable coolant pump of an internal combustion engine having a pump housing in which a pump shaft with an associated impeller is rotatably mounted. The impeller conveys a coolant via an intake connection into a pressure channel of the coolant pump, and a volume flow of the coolant pump is adjustable by a guide plate. The guide plate externally surrounds the impeller at least in some regions, and can be displaced hydraulically between two end positions by a pressure medium.

Vehicles are predominantly driven by water-cooled internal combustion engines. Through the use of a coolant pump, coolant medium is pumped in a closed circuit through coolant channels of the crankcase and of the cylinder head of the internal combustion engine, and the heated coolant medium is subsequently cooled back down in an air-water heat exchanger. To support the circulation of the coolant, a coolant pump is used, in particular driven directly by a belt drive. Due to an immediate coupling between the coolant pump and the crankshaft, the pump rotational speed is a function of the rotational speed of the internal combustion engine. It follows from this that, during a cold start of the internal combustion engine, the coolant circulates, delaying a desired rapid warming up of the internal combustion engine. In order to optimize the operation of internal combustion engines, it is necessary to reach the operating temperature as quickly as possible after a cold start. This reduces frictional losses and fuel consumption, and at the same time reduces emissions values. In order to achieve this effect, regulatable coolant pumps are used which have a conveyed volume flow that can be adapted to the cooling requirement of the internal combustion engine. After a cold start, first a zero conveying by the coolant pump is sought, and subsequently the volume flow for the cooling of the internal combustion engine continuously increases as a function of the temperature level that arises. In series of trials for optimizing the fuel consumption of internal combustion engines, rigorously applied measures for thermal management, inter alia in connection with regulated coolant pumps, succeeded in achieving a reduction in fuel consumption of ≧3%.

From DE 199 01 123 A1, a regulated coolant pump is known in which an external overlapping sliding element is allocated to the impeller as a measure for influencing the volume flow. The effective vane width of the impeller can be modified by the sliding element, which can be continuously axially adjusted by rotating a threaded guide.

US 20110162597 discloses a regulatable coolant pump for a coolant circuit of an internal combustion engine, driven by a traction mechanism drive. In order to influence a conveyed quantity, an axially displaceable guide disk is allocated to the impeller, with the disc being axially displaceable by a push rod, placed inside the hollow shaft of the impeller, in connection with an actuator. The actuator comprises an anchor fixedly connected to the pushrod, said anchor being axially displaceable in a targeted manner via a proportional magnet. For this purpose, the electrically actuated actuator is situated before the belt pulley at the end face, and influences the axial constructive length of the coolant pump.

The regulated coolant pump according to DE 10 2005 062 200 A1 has a driven shaft, mounted in the pump housing, having an associated impeller and a valve slide that can be displaced pneumatically or hydraulically and that variably covers an outflow region of the impeller. On the valve slide there are situated a plurality of piston rods distributed about the circumference that run parallel to the pump shaft in the pump housing and that are guided in annular grooves or bores and are sealed in the pump housing by rod seals. The piston rods stand in operative connection at the annular groove with an annular piston placed in a pressure chamber. A displacement of the annular piston, acted on by pressure springs, and of the valve slide connected thereto takes place via charging of the pressure chamber with pressure, which has a pressure connection bore for this purpose.

US 20130052046 provides a regulated coolant pump in which the guide plate, together with an end face of the pump shaft and the impeller, delimit a pressure chamber that is used to move the guide plate to regulate flow. A pressure medium is fed through the pump shaft into the pressure chamber in order to actuate the regulator.

Axial packaging space in an engine compartment is at a premium, and actuation components for regulatable coolant pumps typically require more axial space and also do not allow for a variable flow. Reciprocating micro-pumps that have been proposed introduce additional mechanical complexity and cost. There is the need for an axially compact pressure medium source for actuating such regulated coolant pumps.

SUMMARY

Briefly stated, a regulatable coolant pump for an internal combustion engine is provided. The pump comprises a pump housing in which a pump shaft and associated impeller is rotatably mounted, that conveys a coolant into an outlet of the coolant pump. A volume flow of the coolant pump is adjustable by a cover that at least one of externally surrounds the impeller at least in some regions, or blocks an inlet flow to the coolant pump. The cover is hydraulically displaceable by an actuator between two end positions. The actuator includes: a solenoid in contact with a piston that is movable into a piston pressure chamber via actuation of the solenoid in order to generate a high pressure pulse of a pressure medium, a return spring that acts to return the piston to an initial position, a plunger chamber in communication with the pressure chamber via a communication path in order to receive a high pressure pulse of the pressure medium, a plunger located in the plunger chamber, and a check valve located in the communication path to prevent a back flow of the pressure medium from the plunger chamber. The plunger is connected to the cover so that upon actuation of the solenoid, the cover is moved by the pressure medium acting on the plunger to an actuated end position in which the impeller is surrounded at least in some regions by the cover or the inlet of the coolant pump is blocked.

In one embodiment, the communication path extends through the pump shaft.

In another embodiment, the piston pressure chamber extends radially from the pump shaft. Here, the piston pressure chamber is preferably in an upper cap, that together with a lower cap are connected together around the pump shaft, and the piston pressure chamber is in communication with radial cross-bores located in the pump shaft. A labyrinth seal is formed by annular projections on the upper and lower caps that are received in annular grooves in the pump shaft on either side of the radial cross-bores. An axial bore located in the pump shaft is connected to a plunger chamber which is located at an impeller end of the pump shaft. This provides for an axially compact arrangement since the actuator in the form of the solenoid and piston can be arranged radially with respect to the pump shaft axis rather than requiring additional axial space.

In another aspect, the cover is rotationally fixed to the impeller, and covers the impeller blades in the actuated end position. Preferably, a return spring acts on the plunger to return the cover to a non-actuated end position. This acts as a fail-safe in the event of a power failure to the solenoid so that the coolant pump can operate in all conditions when control of the actuator is interrupted.

In another aspect, the actuator is connected to the pump housing, and the cover comprises a non-rotatable ring that covers radially ends of the impeller in the actuated end position. This interrupts the flow through the coolant pump outlet and also avoids the need for including a rotatable seal along the communication path between the piston pressure chamber and the plunger chamber. Further, this allows for three-dimensionally curved pump vanes to be utilized since the cover does not have to pass over the vanes as it is moved between the non-actuated and actuated positions.

In another aspect, the actuator is variably actuatable by varying an actuation frequency of the solenoid. This allows for a volume flow control of the pump rather than an on/off arrangement.

In another aspect, the cover is connected to the pump shaft and covers an inlet of the coolant pump in the actuated end position. In this arrangement, preferably guide posts are located on the cover and extend through openings in the impeller. The cover itself is located between the vanes in a central region of the impeller, also allowing for the possibility of three-dimensionally curved vanes.

In another aspect of the invention, the labyrinth seal on the pump shaft is formed by a sleeve which includes the annular grooves rather than having to provide annular grooves in the pump shaft itself. This allows for repair of the labyrinth seal by replacement of the sleeve when the coolant pump is being rebuilt rather than requiring replacement of the entire pump shaft.

In order to replenish the piston chamber, preferably a relief valve is located in a wall of the piston chamber in order to allow the pressure medium to return into piston chamber upon an upstroke of the piston. Alternatively, the piston itself may include radial and axially holes defined therein, with the radial hole being alignable with a coolant relief passage at a given stroke position of the piston in order to recharge the piston chamber.

Preferably, for all embodiments, the pressure medium is in fact the coolant being displaced by the coolant pump. This means that leakage between the plunger and the plunger chamber can be directly into the coolant flow path in order to allow the plunger to return to its non-actuated position under power of the return spring when the solenoid is not actuated. This also eliminates the requirement for a more complex assembly if a different pressure medium were to be utilized.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing Summary as well as the following detailed description will be best understood when read in conjunction with the appended drawings. In the drawings:

FIG. 1 a perspective view of a coolant pump in accordance with the invention with the cover removed in order to show the impeller.

FIG. 2 is a front elevational view of the coolant pump shown in FIG. 1.

FIG. 3 is a cross-sectional view taken along line 3-3 in FIG. 2.

FIG. 4 is a perspective, cross-sectional view of the pump shaft for one embodiment of the invention.

FIG. 5 is a partial cross-sectional view of an alternate arrangement of the piston and piston chamber.

FIG. 6 is a partial cross-sectional view showing an alternate arrangement of the labyrinth seal on the pump shaft.

FIG. 7 is an alternate embodiment of the actuator and cover in which the cover is non-rotatably arranged on the pump housing.

FIG. 8 is a partial cross-section view of an alternate embodiment of the actuator system in which the cover is arranged to cover an inlet of the coolant pump.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Certain terminology is used in the following description for convenience only and is not limiting. The words “front,” “rear,” “upper” and “lower” designate directions in the drawings to which reference is made. The words “inwardly” and “outwardly” refer to directions toward and away from the parts referenced in the drawings. These terms and terms of similar import are for ease of description when referring to the drawings and should not be considered limiting. “Axially” refers to a direction along the axis of a shaft. A reference to a list of items that are cited as “at least one of a, b, or c” (where a, b, and c represent the items being listed) means any single one of the items a, b, or c, or combinations thereof.

Referring to FIGS. 1-4, a first embodiment of a regulatable coolant pump 10 for an internal combustion engine is shown. The coolant pump 10 includes a housing 12 in which a pump shaft 16 is supported via a bearing 14, as shown in FIG. 3. A seal 18 is preferably located between the coolant flow side of the pump 10 and the bearing 14. As shown in FIGS. 1-3, an impeller 20 having vanes 22 is mounted on the pump shaft 16. The coolant pump 10 conveys a coolant from an inlet to an outlet where it generally flows through coolant passages in an internal combustion engine during operation. The coolant flow returns through a heat exchanger and to the coolant pump inlet, typically in a front cover of the pump housing, for example as indicated at 80″ in connection with the embodiment of FIG. 8.

As shown in FIG. 3, the coolant pump 10 in accordance with the first embodiment of the invention is provided with an adjustable volume flow which is controlled by a cover 24 that at least one of externally surrounds the impeller 20 at least in some regions. The cover 24 is hydraulically displaceable by an actuator 28 between two end positions. Preferably, the cover 24 is continuously displaceable between the two end positions to adjust the coolant flow through the coolant pump for example from a no flow or minimal flow position when the internal combustion engine is cold, to an intermediate position as the engine nears an ideal operating temperature, to a full flow condition when the internal combustion engine has warmed up so that the operating temperature of the internal combustion engine can be controlled more precisely. In the first embodiment, the cover 24 has slots that correspond to the position of the vanes 22 of the impeller 20 so that it can move from a position where the cover 24 is pressed against the base of the impeller 20 to a no flow or minimal flow position, as shown in FIG. 3 where the cover is axially shifted to extend over the vanes 22.

Still with reference to FIG. 3, the actuator 28 is preferably includes a solenoid 30, preferably mounted on the housing 12, that is in contact with a piston 32 that is movable into a piston pressure chamber 42 via actuation of the solenoid 30 in order to generate a series of high pressure pulses of a pressure medium, which is preferably the coolant itself, flowing through the coolant pump 10. The piston 32 preferably travels in a guide 34 and is supported on the side opposite the solenoid 30 via a return spring 36 which returns the piston 32 to an initial position when the solenoid is not actuated. A seal 38 is also provided beneath a cap 40 in order to prevent the pressure medium from escaping from the water pump 10 via the solenoid opening 30. In order to recharge the piston chamber 42 prior to a next stroke of the piston 32, a relief check valve 44 is located in the side of the pressure chamber 42.

The piston chamber 42 is connected via a communication path to a plunger chamber 56 in order to receive the high pressure pulses of the pressure medium. As shown in the embodiment of FIG. 3, the communication path is formed via the pressure chamber 42 being in communication with radial cross-bores 46 in the pump shaft 16. The radial cross-bores are intersected via an axial bore 48 which leads to the impeller end of the pump shaft 16. FIG. 4 shows the arrangement of the cross-bore holes 46 and the axial bore hole 48 as well as the plunger chamber 56. A check valve 50 is located along the axial bore 48 in order to prevent a back flow of the pressure medium from the plunger chamber 56 into the radial cross-bores 46. As shown in FIG. 3, preferably the piston pressure chamber 42 extends radially from the pump shaft 16 in an upper cap 58 located in the pump housing 12. The upper cap 58 is connected with a lower cap 60 about the pump shaft 16. Here the piston pressure chamber 42 is aligned with the radial cross-bores 46 in the pump shaft 16. A labyrinth seal 62 is formed on either side of the radial cross-bores 46 by annular projections on the upper and lower caps 58, 60 being received in annular grooves 64 in the pump shaft 16, shown in FIG. 4. This seals the pathway to the radial cross-bores 46 so that the high pressure pulse of the pressure medium can be delivered to the plunger chamber 56 located at the impeller end of the pump shaft 16.

Still with reference to FIG. 3, the first preferred embodiment, the cover 24 is rotationally affixed to the impeller 20, and covers the impeller blades 24 in the actuated end position, which is shown in FIG. 3. It is noted that a return spring 54 acts on the plunger 52 in order to return the cover 24 to a non-actuated end position when the solenoid 30 is not being actuated. This acts as a fail-safe in the event that the solenoid loses power or control is lost to the solenoid, in which case the pressure medium located in the plunger chamber 56 between the plunger 52 and the check valve 50 can bleed out through the small gap between the plunger 52 and the sidewall of the plunger chamber 56. To the extent that the solenoid 30 is continuously actuated, this more than offsets the losses which occur between the plunger 52 and the wall of the plunger chamber 56.

In operation, the plunger 52 is connected to the cover 24 so that actuation of the solenoid 30 moves the cover 24 by the pressure medium building up in the pressure chamber 56 and acting on the plunger 52 to move to an actuated end position, as shown in FIG. 3, which the impeller is surrounded, at least in some regions. Here, the actuator 28 can be variably actuatable by varying an actuation frequency of the solenoid 30.

FIG. 5 shows an alternate arrangement for recharging the pressure chamber 42. In order to resupply the pressure medium to the pressure chamber 42 prior to a next stroke of the piston 32′, it is possible to configure the piston 32′ with a radial bore hole 70 as well as an axially extending bore hole 72 that intersects the radial bore hole 70. At one stroke position of the piston 32′, the radial hole 70 is aligned with a coolant relief passage 74 in order to recharge the pressure chamber 42 with the pressure medium.

By providing the radially mounted solenoid 30, a regulatable coolant flow can be provided within a tighter axial packaging space. This arrangement also provides less wear parts in comparison to alternate pump arrangements.

Referring to FIG. 6, an alternate arrangement of the labyrinth seal 62′ is shown. Here, a seal sleeve 66′ is located on the pump shaft 16′ and the grooves 64′ are located in the seal sleeve 66′. Otherwise, this arrangement is the same as the embodiment of the regulatable coolant pump 10 shown in FIG. 1.

Referring now to FIG. 7, an alternate arrangement of the coolant pump 10″ is shown. Here the actuator 28″ includes a solenoid 30″ which is affixed to the housing 12″ of the pump 10″. The piston 32″ is acted upon by the solenoid 30″ in the same manner as discussed above. In this embodiment, the piston 32″ is shown with the radial hole 70″ as well as the axial hole 72″ for connection to a coolant relief passage 74″ in order to allow recharging of the pressure chamber 42″. The check valve 50″ is located along the communication path between the pressure chamber 42″ and the plunger chamber 56″. The plunger 52″ is shown and is connected to a cover 24″ that is non-rotatable in the housing 12″ and is positioned around the pump shaft 16″. The shaft 16″ is supported via the bearing 14″ in the pump housing 12″. Upon actuation the solenoid 30″, the pressure pulses from the pressure chamber 42″ generated by the piston 32″ are transmitted to the plunger chamber 56″ in order to move the plunger 52″ against the force of return spring 54″ in order to move the cover 24″ into a position where it at least partially surrounds the radial ends of the vanes 22″ or the impeller 20″, blocking the outlet 82″ of the coolant pump 10″. A seal 84″ can be provided in the housing 12″ which the ends of the cover 24″ contact when the actuator 28″ is in use.

The coolant pump 10″ operates generally in the same manner as the coolant pump 10 noted above in that the solenoid 30″ is actuated in order to generate high pressure pulses of the pressure medium, which is preferably the coolant, in order to move the plunger 52″ against the force of the spring 54″ in order to move the cover 24″ into a position in which the flow through the coolant pump 10″ is at least partially or fully blocked, in this case by blocking the outlet 82″.

Referring now to FIG. 8, a third embodiment of the pump 110 is partially illustrated. Here, the cover 124 is mounted on the plunger 152 in the same manner as in the regulatable coolant pump 10. However, the cover 124 is positioned between the vanes 122 of the impeller 120. Upon actuation of the solenoid, the plunger 152 moves the cover 124 into a position where it blocks the inlet 180 in order to prevent coolant from flowing into the pump 110 in the actuated end position. Here, preferably guide posts 178 are connected to the cover 124 that extend through openings in the impeller 120. The pump 110 functions in a similar manner to the first and second embodiments 10 and 10″ discussed above, here by blocking or at least partially blocking the flow of coolant through the inlet of the pump.

Having thus described the present invention in detail, it is to be appreciated and will be apparent to those skilled in the art that many physical changes, only a few of which are exemplified in the detailed description of the invention, could be made without altering the inventive concepts and principles embodied therein. It is also to be appreciated that numerous embodiments incorporating only part of the preferred embodiment are possible which do not alter, with respect to those parts, the inventive concepts and principles embodied therein. The present embodiment and optional configurations are therefore to be considered in all respects as exemplary and/or illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all alternate embodiments and changes to this embodiment which come within the meaning and range of equivalency of said claims are therefore to be embraced therein.

Claims

1. A regulatable coolant pump of an internal combustion engine, comprising a pump housing in which a pump shaft with an associated impeller is rotatably mounted, that conveys a coolant into an outlet of the coolant pump, a volume flow of the coolant pump being adjustable by a cover that at least one of externally surrounds the impeller at least in some regions or blocks an inlet flow to the coolant pump, the cover is hydraulically displaceable by an actuator between two end positions, the actuator including: a solenoid in contact with a piston that is moveable into a piston pressure chamber via actuation of the solenoid in order to generate high pressure pulses of a pressure medium,a return spring that acts to return the piston to an initial position,a plunger chamber in communication with the pressure chamber via a communication path in order to receive the high pressure pulse of the pressure medium,a plunger located in the plunger chamber,a check valve located in the communication path to prevent a backflow of the pressure medium from the plunger chamber;

2. The coolant pump as recited in claim 1, wherein the communication path extends through the pump shaft.

3. The coolant pump as recited in claim 2, wherein the pressure chamber extends radially from the pump shaft in an upper cap that together with a lower cap are connected together around the pump shaft, to radial cross-bores located in the pump shaft, a labyrinth seal being formed by annular projections on the upper and lower caps being received in annular grooves in the pump shaft on either side of the radial cross-bores, and an axial bore in the pump shaft is connected to the plunger chamber which is located at an impeller end of the pump shaft.

4. The coolant pump as recited in claim 3, wherein the cover is rotationally fixed to impeller and at least partially covers the impeller blades in the actuated end position.

5. The coolant pump as recited in claim 1, wherein a return spring acts on the plunger to return the cover to a non-actuated end position.

6. The coolant pump as recited in claim 1, wherein the actuator is connected to the pump housing and the cover comprises a non-rotatable ring that at least partially covers radial ends of the impeller in the actuated end position.

7. The coolant pump as recited in claim 1, wherein the actuator is variably actuatable by varying an actuation frequency of the solenoid to adjust a coolant flow through the coolant pump.

8. The coolant pump as recited in claim 1, wherein the cover is connected to the pump shaft and covers an inlet of the coolant pump in the actuated end position.

9. The coolant pump as recited in claim 8, wherein guide posts are located on the cover and extend through openings in the impeller.

10. The coolant pump as recited in claim 1, wherein the pressure chamber extends radially from the pump shaft in an upper cap that together with a lower cap are connected together around the pump shaft, to radial cross-bores located in the pump shaft, a labyrinth seal being formed by annular projections on the upper and lower caps being received in annular grooves in a sleeve located on the pump shaft on either side of the radial cross-bores, and an axial bore in the pump shaft is connected to the plunger chamber which is located at an impeller end of the pump shaft.

11. The coolant pump as recited in claim 1, wherein a relief check valve is located in the pressure chamber.

12. The coolant pump as recited in claim 1, wherein the piston has radial and axial holes defined therein, and the radial hole is alignable with a coolant relief passage at one stroke position of the piston to recharge piston chamber.

13. The coolant pump as recited in claim 1, wherein the pressure medium is the coolant.