Mechanical coolant pump   

Abstract: A mechanical coolant pump for an internal combustion engine includes a main pump body comprising a volute housing and an outlet channel. A pump wheel is arranged in the volute housing. The pump wheel is configured to pump a coolant into the outlet channel. A volute tongue wall comprising a flap is configured to be axially pivotable. The volute tongue wall is configured to separate the outlet channel from a volute. An outlet valve defined by the flap of the volute tongue wall in an open position forms an end of the volute tongue wall. The outlet valve is configured to control a coolant outlet flow of the mechanical coolant pump. A pivot axis of the flap is arranged adjacent to the volute housing.

This application is a U.S. National Phase application under 35 U.S.C. § 371 of International Application No. PCT/EP2010/051918, filed on Feb. 16, 2010. The International Application was published in English on Aug. 25, 2011 as WO 2011/101019 A1 under PCT Article 21(2).

The present invention relates to a mechanical coolant pump for an internal combustion engine.

A mechanical coolant pump is a coolant pump which is driven by the combustion engine, for example, by using a driving belt driving a driving wheel of the pump. As long as the combustion engine is cold, only a minimum coolant flow is needed. Therefore, mechanical coolant pumps are used which are provided with an outlet valve for controlling the coolant circulation flow. As long as the combustion engine is cold, the outlet valve is closed so that the circulation of the lubricant is minimized, with the result that the combustion engine warming-up phase is decreased.

Usually, outlet valves are used in the form of a pivoting flap, whereby the pivoting flap is positioned in the pump outlet channel. The pivoting flap is controlled to rotate into an open or closed position, whereby the positions determine the coolant circulation flow rate. The arrangement of such a pivoting flap inside the coolant outlet channel restrains the coolant flow even in the open position of the flap and induces a useless flow resistance. Furthermore, when the flap is in the closed position, turbulence is generated in the coolant, in the volute and in the outlet channel, so that the pump wheel is permanently exposed to a significant resistance caused by the turbulence in the coolant. This resistance causes a useless energy consumption of the coolant pump in the idle state of the coolant pump.

SUMMARY

An aspect of the present invention is to provide a mechanical coolant pump with a decreased fluidic resistance.

In an embodiment, the present invention provides a mechanical coolant pump for an internal combustion engine which includes a main pump body comprising a volute housing and an outlet channel. A pump wheel is arranged in the volute housing. The pump wheel is configured to pump a coolant into the outlet channel. A volute tongue wall comprising a flap is configured to be axially pivotable. The volute tongue wall is configured to separate the outlet channel from a volute. An outlet valve defined by the flap of the volute tongue wall in an open position forms an end of the volute tongue wall. The outlet valve is configured to control a coolant outlet flow of the mechanical coolant pump. A pivot axis of the flap is arranged adjacent to the volute housing.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is described in greater detail below on the basis of embodiments and of the drawings in which:

FIG. 1 shows a perspective view of a mechanical coolant pump with a valve flap in the open position; and

FIG. 2 shows a perspective view of the mechanical coolant pump with the valve flap in the closed position.

DETAILED DESCRIPTION

The mechanical coolant pump for an internal combustion engine according to the present invention comprises a main pump body which comprises a volute housing. A pump wheel is arranged inside the volute housing, whereby the pump wheel pumps the coolant outwardly into the volute and from the volute tangentially into the outlet channel. The coolant outlet flow of the pump is controlled by an outlet valve. The outlet channel is separated by a volute tongue wall from the volute, so that the volute tongue wall separates the outlet channel from the volute.

The outlet valve of the mechanical coolant pump is defined by an axially pivotable flap being at least a part of the volute tongue wall in the open position of the flap. The flap forms the end of the volute tongue wall in the circumferential direction. The pivot axis of the pivotable flap is orientated axially and parallel to the rotating axis of the pump wheel. The pivot axis is arranged adjacent to the volute housing over the entire length of the flap pivot axis.

The arrangement of the axially pivotable flap adjacent to the volute housing and at the end of the volute tongue wall avoids the flow of any coolant into the outlet channel when the flap is in the closed position because the closed flap directly closes the inlet of the outlet channel and is not arranged in the course of the outlet channel anymore. As a result, the fluidic resistance for the pump wheel caused by turbulence in the coolant is significantly reduced in the closed flap position. In the closed flap position, a flow of the coolant into the outlet channel and back is stopped effectively so that a coolant ring rotates in the volute. This means that the coolant ring flowing in the volute circulates in a constant and mainly undisturbed manner. As a result, the energy consumption of the pump decreases significantly when the outlet valve is closed. Energy consumption during the cold start phase of the engine while the outlet valve is closed can in particular be minimized effectively.

The pump is also provided with a reduced flow resistance in the open position because the flap does not provide a useless flow resistance for the coolant, in contrast to a flap, which is positioned in the middle of the outlet channel and which restrains the coolant flow in the outlet channel.

In an embodiment of the present invention, the main pump body can, for example, be provided with at least one stopping element which stops the flap in the defined open position and/or defined closed position. A stopping element holds the flap in the defined open and/or defined closed position so that the actuator which opens and closes the flap does not have to apply holding forces to the flap in the open or closed position. This is an additional means to decrease the energy consumption of the actuator moving the flap.

In an embodiment of the present invention, the stopping element can, for example, be a stopping nose arranged in the outlet channel wall, and the flap can be stopped by the stopping nose in the closed position. A stopping nose is a simple and cost-efficient means to realize a stopping element which supports the flap in its closed position.

In an embodiment of the present invention, the flap can, for example, be arched and the arched flap can extend the volute in the open position of the flap. In an embodiment of the present invention, the proximal side of the flap can, for example, be arched circular with an inner radius close to the outer radius of the pump wheel. The arched flap extends the volute in the open position so that the coolant flow in the volute and into the outlet channel is undisturbed. The undisturbed coolant flow is mainly free of turbulence so that the energy consumption of the pump decreases in the open position of the flap.

In an embodiment of the present invention, the stopping element can, for example, be a step in the volute housing and the arched flap can be stopped by the stopping element when the flap opens and arrives at the open position. The step, which can be realized in the outer wall of the volute housing or in the side wall of the outlet channel, is a simple and cost-efficient means to realize a stopping element which stops and supports the flap in an open position.

In an embodiment of the present invention, the flap can, for example, be driven by an actuator. In an embodiment of the present invention, the flap can, for example, be driven by a pneumatic actuator. The flap can also be driven by other actuators such as an electrical, a vacuum or a thermostatic actuator. The pneumatic energy can be tapped at different positions at the combustion engine so that the use of a pneumatic actuator is simple and cost-efficient.

In an embodiment of the present invention, the actuator can, for example, position the flap in at least one intermediate position between the open position and the closed position. This makes it possible to adapt the coolant outlet flow more accurately to the coolant needs of the engine. Especially during a cold start phase of the engine, a more precise control of the coolant flow rate is helpful to shorten the warming-up phase of the engine.

In an embodiment of the present invention, the volute housing can, for example, be an integrated part of the main pump body. This construction allows faster and more cost-efficient production.

In an embodiment of the present invention, one part of the volute tongue wall is a part of the pivotable flap and the other part of the volute tongue wall is a part of the volute housing. The pivotable flap should be constructed as small as possible. The bigger the flap is, the higher is the total force of the flowing coolant which causes a torque to the flap. The pivotable flap should, however, be large enough to close the outlet channel in the closing position.

FIG. 1 shows a mechanical coolant pump 10 for an internal combustion engine. The mechanical coolant pump 10 comprises a main pump body 12, whereby the main pump body 12 is mounted directly to the engine block by a flange 40 or can have a separate cover body which is not shown.

The main pump body 12 is provided with a volute housing 14 which is an integrated part of the main pump body 12, whereby the volute housing 14 is substantially forming the volute 34. The volute housing 14 supports a rotatable pump wheel 16 which sucks the coolant axially and pumps the coolant radially outwardly into a volute channel 35 of the volute 34. The volute channel 35 is a ringlike channel which surrounds the pump wheel 16 circumferentially.

The pump wheel 16 is directly driven by the combustion engine by using a driving belt (not shown) which drives a driving wheel (not shown) of the coolant pump 10. The coolant flows, as a result of centrifugal forces, into the volute 34, from the volute channel 35 through an outlet valve 20 into a subsequent outlet channel 18 and finally to an outlet opening 38 of the pump 10. The outlet valve 20 is positioned at the end of the volute channel 35 and separates the volute channel 35 from the outlet channel 18.

The outlet valve 20 comprises an axially pivotable arched flap 24. The pivot axis 26 is arranged adjacent to the volute housing 14. The flap 24 is at least a part of a volute tongue wall 22 in the open position of the flap 24 and is forming the circumferential end of the volute tongue wall 22. The volute tongue wall 22 comprises a wedge-shaped part 23 which is a part of the volute housing 14. The flap 24 extends the volute 34 in the open flap position (FIG. 1).

The flap 24 is stopped in the open position by a stopping element 28 which is a step 36 in an outer wall 39 of the volute housing 14. More precisely, the step 36 is formed by a side wall 37 of the volute channel 35 and the outer wall 39 so that the step fold is orientated tangentially.

In the closed valve position (FIG. 2), the flap 24 is stopped by a stopping element 27 which is a stopping nose 30. The stopping nose 30 is a groove in an outlet channel wall 32. The stopping groove is positioned opposite and parallel to the pivot axis 26 of the flap 24 so that the flap 24 is closable into the closing position shown in FIG. 2. When the flap 24 is in the closing position, the coolant rotates in the volute 34 as a coolant ring, and is circulating in a constant and mainly undisturbed manner.

The flap 24 is driven by an actuator (not shown), which is, for example, a pneumatical, an electrical, a vacuum or a thermostatic actuator. The flap 24 can be positioned in at least one intermediate position by the actuator. The intermediate position is a defined position between the open and the closed flap position, and allows the control of the coolant outlet flow more accurate and more adapt to the coolant need of the engine.

The present invention is not limited to embodiments described herein; reference should be had to the appended claims.