EP3371465B1 - Coolant pump for an internal combustion engine - Google Patents

Description

The invention relates to a coolant pump for an internal combustion engine having a drive shaft, a coolant pump impeller which is at least rotationally fixed on the drive shaft and via which coolant is conveyed, an adjustable control slide, via a free cross-section of an annular gap between an outlet of the coolant pump impeller and the surrounding conveyor channel is controllable, a control pump with a Regelpumpenlaufrad, which is at least rotationally fixed on the drive shaft, a flow channel of the control pump in which by rotation of the Regelpumpenlaufrades a pressure can be generated, a pressure channel through which an outlet of the flow channel with a first pressure chamber of the control slide fluidly is connectable, which is formed on the side facing away from the coolant pump impeller axial side of the control slide, and a valve, via which a flow cross-section of the pressure channel closable and releasable i st.

Such coolant pumps are used in internal combustion engines to control the amount of subsidized coolant in order to prevent overheating of the internal combustion engine. The drive of these pumps is usually via a belt or chain drive, so that the Kühlmittelpumpenrad is driven by the speed of the crankshaft or a fixed ratio to the speed of the crankshaft.

In modern internal combustion engines, the pumped coolant quantity is to be adapted to the coolant requirement of the internal combustion engine or of the motor vehicle. To avoid increased pollutant emissions and Reduction of fuel consumption, especially the cold running phase of the engine should be shortened. This is done, inter alia, by throttling or completely shutting off the coolant flow during this phase.

To control the amount of coolant various pump designs have become known. In addition to electrically driven coolant pumps pumps are known which can be coupled via couplings, in particular hydrodynamic couplings to their drive or separated from it. A particularly cost-effective and simply constructed possibility for controlling the conveyed coolant flow is the use of an axially displaceable control slide, which is pushed over the coolant pump impeller, so that promotes the reduction of the coolant flow, the pump not in the surrounding conveyor channel but against the closed slide.

The regulation of these slides also takes place in different ways. In addition to a purely electrical adjustment, especially a hydraulic adjustment of the slide has proven. This is usually done via an annular piston chamber which is filled with a hydraulic fluid, and whose piston is connected to the slider, so that when the space is filled, the slider is moved over the impeller. A return of the slide takes place by opening the piston chamber to an outlet, which is usually done via a solenoid valve and under the action of a spring which provides the force to return the slider.

In order not to have to provide the necessary for the process of the slide coolant amount on additional conveyor units, such as additional piston / cylinder units or to compress other hydraulic fluids for actuation, are mechanically controllable Coolant pumps have become known, on the drive shaft, a second delivery wheel is arranged, via which the pressure for adjusting the slide is provided. These pumps are designed, for example, as side channel pumps or servo pumps.

Such a coolant device with a secondary pump acting as a secondary pump is from the DE 10 2012 207 387 A1 known. In this pump, a pressure side of the secondary pump is closed by a 3/2-way valve in a first position and a suction side of the pump connected to the cooling circuit and the slider and connected in a second position, the pressure side with the slide and the suction side with the cooling circuit. To reset the slide is a spring, which may possibly be waived by a reset of the pump should be made by the resulting negative pressure on the suction port. A detailed channel and flow guidance is not disclosed. The flow guides shown schematically are technically feasible in modern internal combustion engines only with increased effort and space requirements. In addition, it is doubtful whether the force acting on the slider by the negative pressure is sufficiently great to overcome the frictional forces acting during the adjustment.

Furthermore, from the US 2015/0098804 A1 a coolant pump is known in which a hydraulic actuator has a plurality of circumferentially separate pressure chambers through which a rotation is generated. The pressure ring, which is actuated by these pressure chambers, is connected via a transmission with the control slide of the coolant pump, which converts the rotational movement of the pressure ring into a translatory movement of the control slide.

It is therefore the object to provide a coolant pump for an internal combustion engine, in which a provision of the slide in its maximum delivery of the coolant pump locking position in both the control of the pump in normal operation as well as in emergency operation in case of failure of the electrical system and thus the solenoid valve without using a compression spring can be ensured. Furthermore, it is an object to provide a coolant pump available whose channel and coolant guide is feasible in the available space in modern internal combustion engines. In particular, the pump should be able to be arranged as a plug-in pump within a corresponding recess in the crankcase.

This object is achieved by a coolant pump with the features of the main claim 1.

Characterized in that the flow channel is fluidly connected via a connecting channel with a second pressure chamber of the control slide, which is formed on the pointing to the coolant pump impeller axial side of the control slide, in case of failure of the valve and thus closed connection to the first pressure chamber on the opposite side of the control slide Built pressure through which the control slide, without having to use a return spring, is reliably pushed into his the coolant pump impeller releasing position. Thus, an emergency running position of the control slide is ensured in case of failure of the electrical supply in which a maximum coolant delivery to the engine and thus overheating of the engine is avoided.

Preferably, the valve is a 3/2-way solenoid valve, which is easy to control and has a small footprint, so that integration into the housing of the coolant pump is possible. By controlling the valve this can be moved to intermediate positions, which also lead according to the shared cross-section to a complete position control of the control slide.

In a preferred embodiment, the control pump impeller is formed integrally with the coolant pump impeller. Accordingly, both wheels can be manufactured and assembled in one manufacturing step. In addition, the required axial space is reduced.

In an advantageous embodiment of the invention, the flow channel of the control pump is arranged in a first fixed housing part, on the axially opposite to the flow channel side of the second pressure chamber is formed. This housing part serves at the same time as the axial boundary of the second pressure chamber and the flow housing of the control pump. In addition, this housing part can serve as a sliding surface and thus guide for the control slide.

In a further preferred embodiment, the connecting channel is formed in the fixed, the flow channel having housing part. This can be done by forming a simple bore, so that no additional lines between the flow channel and the second pressure chamber must be mounted. The manufacture and assembly of the coolant pump and their space requirements are reduced accordingly.

A reliable function in the control of the slide results when the connecting channel extends from a region of an inlet of the control pump in the second pressure chamber. By this arrangement, a pressure in the second pressure chamber is built up only when the valve is closed, so when a delivery pressure of the pump through the closure of the outlet also arises at the inlet. Otherwise, there is always only the lower pressure in the region of the inlet of the control pump in the second pressure chamber.

Preferably, the Regelpumpenlaufrad is at the rear of the coolant pump impeller axially between the second pressure chamber and the coolant pump impeller arranged. In addition to the axially short design, which is made possible by this arrangement, this also short flow paths for connecting the pressure chambers with the delivery channel or the impeller of the control pump are created.

In a further preferred embodiment of the invention, the control pump is a side channel pump, so that the delivery channel can be arranged axially opposite to the impeller. This is particularly suitable for generating high discharge pressures at low flow rates.

Advantageously, the pressure channel extends from the outlet of the control pump through the first housing part and a second housing part to the first pressure chamber, wherein in the second housing part of the controlled by the valve flow area is formed. This design creates a very compact coolant pump without additional connecting lines.

In a further advantageous embodiment, the pressure channel in the first housing part is formed radially inside the control slide and the first housing part bounds the two pressure chambers radially inward. The first housing part can thus simultaneously serve as the inner guide of the control slide. The channels can be made very short, whereby the reaction time of the control is reduced.

There is thus provided a coolant pump for an internal combustion engine in which the control slide is purely hydraulic, both in normal operation and in the case of the emergency operation, so that no additional components, such as springs and the like are required, sufficient promotion of coolant to prevent overheating to provide the internal combustion engine. Furthermore, only a very small space is required for this pump. The coolant pump according to the invention is also easy and inexpensive to manufacture and assemble.

• Figur 1 zeigt eine Seitenansicht einer erfindungsgemäßen Kühlmittelpumpe in geschnittener Darstellung.
• Figur 2 zeigt eine zu Figur 1 gedrehte Seitenansicht des erfindungsgemäßen Kühlmittelpumpe in geschnittener Darstellung.

An embodiment of a coolant pump according to the invention for an internal combustion engine is shown in the figures and will be described below,

• FIG. 1 shows a side view of a coolant pump according to the invention in a sectional view.
• FIG. 2 shows one too FIG. 1 rotated side view of the coolant pump according to the invention in a sectional view.

The coolant pump according to the invention consists of an outer housing 10 in which a spiral conveying channel 12 is formed, in which a coolant is sucked in via an axial pump inlet 14 which is likewise formed in the outer housing 10, which coolant flows via the delivery channel 12 to a tangential pump outlet 16 and formed in the outer housing 10 is conveyed into a cooling circuit of the internal combustion engine.

For this purpose, a coolant pump impeller 20 is fixed radially inside the conveying channel 12 on a drive shaft 18, which is designed as a Radialpumpenrad, by the rotation of the promotion of the coolant takes place in the conveying channel 12. At the pump inlet 14 opposite axial side of the coolant pump impeller 20, a control pump impeller 22 is formed, which is rotated in accordance with the coolant pump impeller 20. This control pump impeller 22 has blades 23 which are arranged axially opposite to a flow channel 24 formed as a side channel, which is formed in a first inner housing part 26. In this first housing part 26, an inlet and an outlet 30 are formed, so that the control pump impeller 22 with the flow channel 24 a Regulating pump 32 forms, via which the pressure of the coolant from the inlet to the outlet 30 is increased.

The drive of the coolant pump impeller 20 and the control pump impeller 22 via a belt 34 which engages in a pulley 36 which is secured to the coolant pump impeller 20 opposite axial end of the drive shaft 18. The pulley 36 is mounted on a double-row ball bearing 38, the outer ring 40 is pressed on the pulley 36 and the inner ring 42 on a second inner housing part 44. The second housing part 44 has an inner axial passage opening 46 into which an annular projection 48 of the first housing part 26 protrudes, via which the first housing part 26 is fastened to the second housing part 44. The second housing part 44 is fastened to the outer housing 10 with the interposition of a seal 50. For this purpose, the outer housing 10 at its pump inlet 14 opposite axial end has a receiving opening 52 into which an annular projection 54 of the second housing part 44 protrudes, on the peripheral wall of a groove 56 is formed, in which the seal 50 is arranged.

This projection 54 also serves as a rear stop for a control slide 58, the cylindrical peripheral wall 60 can be pushed over the coolant pump impeller 20 so that a free cross section of an annular gap 62 between an outlet 64 of the coolant pump impeller 20 and the delivery channel 12 is controlled. In accordance with the position of this control slide 58, the coolant flow conveyed through the coolant circuit is thus regulated.

The control slide 58 has, in addition to the peripheral wall 60, a bottom plate 66 with an inner opening 68, from the outer periphery of which the peripheral wall 60 axially through an annular gap 70 between the first housing part 26 and the outer housing 10 in the direction of axially adjacent annular gap 62 extends. At the inner circumference and at the outer periphery of the bottom plate 66, a radial groove 72, 74 is formed in each of which a piston ring 76, 78 is arranged, via which the control slide 58 in the radially inner region on the first housing part 26 and in the radially outer region in the receiving opening 52 of the outer housing 10 is slidably mounted.

According to the invention is located on the side facing away from the coolant pump impeller 20 side of the control slide 58, a first pressure chamber 80 axially through the second housing part 44 and the bottom plate 66 of the control slide 58 and radially outwardly through the outer housing 10 and the annular projection 54 of the second housing part 44 and is bounded radially inwardly by the first housing part 26. On the side facing the coolant pump impeller 20 side of the bottom plate 66, a second pressure chamber 82 is formed, which is axially bounded by the bottom plate 66 and the first housing part 26, radially outwardly through the peripheral wall 60 of the control slide 58 and radially inwardly through the first housing part 26 , Depending on the pressure difference applied to the bottom plate 66 of the control slide 58 in the two pressure chambers 80, 82, the peripheral wall 60 of the control slide 58 is correspondingly pushed into or out of the annular gap 62 into the annular gap 62.

The pressure difference required for this purpose is generated by the control pump 32 and supplied to the respective pressure chamber 80, 82 by means of a valve 84, which is designed as a 3/2-way solenoid valve. For this purpose, a receiving opening 86 for the valve 84 is formed in the second housing part 44, via which, depending on the position of its closing body 88, a flow cross-section 90 of a pressure channel 92 is regulated. This pressure channel 92 extends from the outlet 30 of the flow channel 24 of the control pump 32 initially into a radially inner region of the first housing part 26 and from there axially into the second housing part 44, in the the controllable flow cross-section 90 of the pressure channel 92 is formed, which is closable and releasable by the closing body 88 of the solenoid valve 84. From this controllable flow cross-section 90, the pressure channel 92 extends further into the first pressure chamber 80. The second pressure chamber 82 is connected via a connecting channel 94, which is formed in the first housing part 26, with the flow channel 24, said connecting channel 94 formed by a bore is that extends from a region of the inlet from the flow channel 24 directly into the second pressure chamber. A third, not shown, flow connection of the control valve leads to the suction side of the coolant pump.

If the coolant pump to promote a maximum amount of coolant during operation, the annular gap 62 at the outlet 64 of the coolant pump impeller 20 is fully released by the solenoid valve 84 is not energized, whereby the closing body 88 is moved due to a spring force in its the flow cross-section 90 of the pressure channel 92 occlusive position , As a result, no pressure is built up by the coolant in the first pressure chamber 80, but the coolant present in the pressure chamber 80 can flow to the pump inlet 14 of the coolant pump via the not shown other flow connection of the solenoid valve 84, which is released in this state. Instead, in this state, the control pump 32 promotes against the closed flow cross-section 90, whereby an increased pressure builds up in the entire flow channel 24, which also acts in the region of the inlet of the control pump and correspondingly builds up via the connecting channel 94 in the second pressure chamber 82. This increased pressure in the second pressure chamber 82 has the result that a pressure difference arises on the bottom plate 66 of the control slide 58, which results in that the control slide 58 is displaced into its position releasing the annular gap 62 and thus a maximum delivery the coolant pump is ensured. In case of failure of the electrical supply of the solenoid valve 84, the control slide 58 assumes the same position, so that a maximum delivery of the coolant pump is ensured in this emergency mode, without the need for a return spring or other, non-hydraulic force would be necessary. An excessive increase of the pressure in the second pressure chamber 82 is avoided, inter alia, by a leakage over the gap 70 between the first housing part 26 and the peripheral wall 60, so that the additionally funded by the control pump 32 coolant is also used for promotion in the cooling circuit. The coolant from the first pressure chamber can flow off via a return duct, not shown, which extends from the solenoid valve 84 through the second housing part 44 and then along the drive shaft 18 in the interior of the first housing part 26 and leads via a bore in the coolant pump impeller 20 to the pump inlet 14 of the coolant pump ,

If a reduced coolant flow to the cooling circuit is required by the engine control, as is the case for example during warm-up of the internal combustion engine after cold start, the solenoid valve 84 is energized, whereby the closing body 88 releases the flow cross-section 90 of the pressure channel 92. Accordingly, the pressure arising at the outlet 30 of the control pump 32 is also generated in the pressure channel 92 and in the first pressure chamber 80, while at the same time the pressure in the second pressure chamber 82 decreases, since in the region of the inlet by the suction of the coolant, a reduced pressure. In this case, the coolant present in the second pressure chamber 82 is initially aspirated. In this state, a pressure difference correspondingly again rests on the bottom plate 66 of the control slide 58, which causes the control slide 58 to be displaced into the annular gap 62 and thus the coolant flow in the cooling circuit to be interrupted. With increased pressure build-up in the first pressure chamber 80 increases after some time also the pressure in the flow channel 24 and in the second pressure chamber 82, which, however, does not lead to a provision, since the leakage from the second pressure chamber 82 is greater than from the first pressure chamber 80 and to adjust an additional frictional force would be overcome. Accordingly, the control slide 58 remains in the desired position, without causing an excessive pressure increase.

If a controllable solenoid valve 84 is used, it is also possible to move the valve 84 in intermediate positions, whereby an equilibrium of forces can be achieved for each position of the control slide 58, so that complete regulation of the flow cross-section of the annular gap 62 is made possible.

The coolant pump described is extremely compact, but easy and inexpensive to produce and assemble. On additional lines for hydraulic connection of the control pump with the pressure chambers of the control slide can be omitted, since they can be formed over very short distances as simple holes in the two inner housing parts. An adjustment of the control slide is done exclusively on the prevailing in the two pressure chambers hydraulic forces !, So that can be dispensed with additional components, such as return springs. Nevertheless, a reliable emergency operation is ensured, since in case of failure of the energization always a pressure difference across the control slide is created, which shifts this in his the annular gap releasing position. In addition, the adjustment in the annular gap closing position of the control slide power requirement is reduced by eliminating the return spring, so that a faster adjustment with smaller cross sections is possible.

It should be clear that the scope of the main claim is not limited to the embodiment described. In particular are other housing divisions or the use of another valve or a differently designed control pump conceivable. Also, the ducts or the boundaries of the pressure chambers can be changed without departing from the scope of the main claim. In addition, for example, a two-piece design of the two pump impellers is conceivable.

Claims (10)

1. A coolant pump for an internal combustion engine, having
   a drive shaft (18),
   a coolant pump impeller (20) which is arranged at said drive shaft (18) at least in a rotationally fixed manner and by means of which a coolant is adapted to be delivered,
   an adjustable control slide (58) by means of which a throughflow cross-section of an annular gap (62) between an outlet (64) of said coolant pump impeller (20) and the surrounding delivery duct (12) is adapted to be controlled,
   a control pump (32) having a control pump impeller (22) which is arranged at said drive shaft (18) at least in a rotationally fixed manner,
   a flow duct (24) of said control pump (32) in which a pressure is adapted to be generated by rotation of said control pump impeller (22),
   a pressure duct (92) via which an outlet (30) of said flow duct (24) is adapted to be fluidically connected to a first pressure chamber (80) of said control slide (58), which is formed on the axial side of said control slide (58) facing away from said coolant pump impeller (20),
   a valve (84) via which a throughflow cross-section (90) of said pressure duct (92) is adapted to be closed and opened,
   characterized in that
   said flow duct (24) is fluidically connected via a connecting duct (94) to a second pressure chamber (82) of said control slide (58), which is formed on the axial side of said control slide (58) facing said coolant pump impeller (20).
2. The coolant pump for an internal combustion engine according to claim 1,
   characterized in that
   the valve (84) is a 3/2-way magnetic valve.
3. The coolant pump for an internal combustion engine according to any one of claims 1 or 2,
   characterized in that
   the control pump impeller (22) is integrally formed with the coolant pump impeller (20).
4. The coolant pump for an internal combustion engine according to any one of the preceding claims,
   characterized in that
   the flow duct (24) of the control pump (32) is formed in a first fixed housing part (26) on whose side axially opposite to said flow duct (24) the second pressure chamber (82) is formed.
5. The coolant pump for an internal combustion engine according to claim 4,
   characterized in that
   the connecting duct (94) is formed in the fixed housing part (26) comprising the flow duct (24).
6. The coolant pump for an internal combustion engine according to any one of the preceding claims,
   characterized in that
   the connecting duct (94) extends from an area of an inlet of the control pump (32) into the second pressure chamber (82).
7. The coolant pump for an internal combustion engine according to any one of the preceding claims,
   characterized in that
   the control pump impeller (22) is arranged on the rear side of the coolant pump impeller (20) axially between the second pressure chamber (82) and the coolant pump impeller (20).
8. The coolant pump for an internal combustion engine according to any one of the preceding claims,
   characterized in that
   the control pump (32) is a side channel pump.
9. The coolant pump for an internal combustion engine according to any one of the preceding claims,
   characterized in that
   the pressure duct (92) extends from the outlet (30) of the control pump (32) through the first housing part (26) and a second housing part (44) into the first pressure chamber (80), wherein in said second housing part (44) the throughflow cross-section (90) governed by the valve (84) is formed.
10. The coolant pump for an internal combustion engine according to claim 9,
    characterized in that
    the pressure duct (92) in the first housing part (26) is formed radially inside the control slide (58) and said first housing part (26) delimits the two pressure chambers (80, 82) radially inwards.

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