Mechanical coolant pump

The present invention refers 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, turbulences are 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. It is an object of the present invention to provide a mechanical coolant pump with a decreased fluidic resistance.

This object is solved with a mechanical coolant pump with the features of claim 1.

The mechanical coolant pump for an internal combustion engine according to claim 1 comprises a main pump body which comprises a volute housing. Inside the volute housing, a pump wheel is arranged, whereby the pump wheel is pumping the coolant outwardly into the volute and from the volute tangential!y 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 axiaiiy pivotable flap being at least a part of the voiute tongue wall in the open position of the flap. The flap is forming the end of the voiute 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 axiaiiy pivotabie 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 closes directly 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 turbulences in the cooiant is significantly reduced in the closed flap position. In the closed flap position, a flow of the cooiant into the outlet channel and back is stopped effectively so that a coolant ring rotates in the voiute. This means that the coolant ring flowing in the volute is circulating in a constant and mainly undisturbed manner. As a result, the energy consumption of the pump decreases significantly when the outlet valve is closed. Especially, the energy consumption during the cold start phase of the engine while the outlet valve is closed can be minimized effectively.

The pump is also provided with a reduced flow resistance in the open position because the flap is not providing 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. According to a preferred embodiment, the main pump body is provided with at least one stopping element and the stopping element is stopping 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 has not 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.

Preferably, the stopping element is a stopping nose arranged in the outlet channel wall and the flap is 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.

Preferably, the flap is arched and the arched flap is extending the volute in the open position of the flap. Preferably, the proximal side of the flap is 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 turbulences so that the energy consumption of the pump decreases in the open position of the flap. Preferably, the stopping element Is a step in the volute housing and the arched flap is 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.

According to a preferred embodiment, the fiap is driven by an actuator. Preferably, the flap is driven by a pneumatic actuator. The flap can also be driven by other actuators like 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, Preferably, the actuator is able to 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 accurate to the coolant need 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.

Preferably, the volute housing is an integrated part of the main pump body. This construction allows faster and more cost-efficient production. According to a preferred embodiment, 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. However, the pivotable flap should be large enough to close the outlet channel in the closing position. The following is a detailed description of the invention with reference to the drawings, in which :

Figure 1 shows a perspective view of a mechanical coolant pump with a valve flap in the open position, and

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

In figure 1, a mechanical coolant pump 10 for an internal combustion engine is shown. 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 axial!y 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 axialiy pivotable arched flap 24. The pivot axis 26 is arranged adjacent to the volute housing 14. The fiap 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 vo!ute tongue wail 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 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 dosing position shown in fig. 2. When the flap 24 is in the closing position, the coolant rotates in the voiute 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 instance, 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.