CN113227580B - Electric screw coolant pump - Google Patents

Abstract

The present invention relates to an electric screw spindle coolant pump adapted to deliver a coolant circuit or other corrosive liquid medium. The electric screw spindle coolant pump has a spindle housing (1) with a spindle chamber (10), and an axially adjacent motor housing (3). The invention is characterized in that the motor housing (3) comprises a motor chamber (30) in which the dry running motor (4) is arranged separate from the flow; and the motor housing (3) has a heat conversion portion (31) through which the flow flows, the heat conversion portion being disposed between the motor chamber (30) and a component boundary of the motor housing (3) to the spindle housing (1).

Description

Electric screw coolant pump

technical field

The present invention relates to an electric coolant pump of the screw pump type for delivering coolant circuits and the like, in particular for delivering aggressive liquid media.

Background technique

Progressive cavity pumps are positive displacement pumps that allow high pressure and high volumetric efficiency. They do not provide geometry adjustment in a speed-independent manner, but they do include robust rotary piston mechanisms that are not prone to fouling and operate without fragile elements such as shut-off valves. As a result, mechanically driven screw pumps have hitherto mainly been used in large-scale applications, such as oil pumps in stationary installations or ship engines, where they operate with a relatively constant operating point.

In the field of fuel delivery pumps for vehicles, smaller electrically driven screw pumps have recently been known which allow higher pressures than centrifugal pumps. These pumps are installed in the vehicle sump in a submerged arrangement and provide high input pressure upstream of the high pressure pump or injection pump in the fuel path. The electric drive of such fuel delivery pumps is designed as a wet-running electric motor without a split tank, and thus both the rotor and the stator are in contact with the fuel. The temperature of the fuel delivered from the reservoir generally corresponds to the ambient temperature of the vehicle. Thus, the transmission, which gets hot due to power dissipation, is easily cooled in these fuel delivery pumps.

Thus, US2018/0216614A1 describes a screw pump provided as a fuel pump. A cover with an axial outlet is attached to the housing of the progressive cavity pump. An electric motor is received in the outlet chamber of the cover and fuel flows through the electric motor before exiting the outlet.

DE 10 2015 101 443 B3 describes a fuel pump with a housing, in which an electric drive motor is coupled to the screw pump. Fuel flows through the drive motor before leaving the pressure side outlet.

WO2014/138519A1 describes an electric liquid pump of the screw type. Fluid flowing through the inlet and outlet also surrounds the motor. Fuels are referred to as liquids. The flange plane shown in the configuration shown between the motor-side housing part and the pump-side housing part extends between the motor and the pump-side outlet.

DE 10 2017 210 771 A1 describes an electrically driven screw pump as fuel delivery assembly. The pump housing and electric motor are received in the casing. In the illustrated embodiment that does not include a split tank on the stator of the electric motor, the electric components of the motor are in direct contact with the fuel within the outlet guide on the pressure side of the spindle chamber.

However, the above-mentioned pump cannot be put into use as an electric water pump, more precisely as an electric coolant pump. A liquid medium such as coolant waiting to be delivered will corrosively damage the exposed components of the electric motor, especially the coil windings of the stator.

US 6,371,744 B1 describes an electric vacuum pump of the screw type. The screw spindle is driven by an electric motor arranged in a separate housing.

Independent of the specific modification between the screw pump for gases and the screw pump for liquids, the vacuum pump cannot be put into use as an electric coolant pump. With the arrangement shown, sufficient cooling of the dry-running electric motor cannot be ensured. In a pressurized coolant cycle, the target temperature of the coolant may be around the boiling temperature of the coolant. In this case, in continuous operation, overheating damage to electrical or electronic components will occur.

Contents of the invention

Based on known electric screw pumps of the prior art which are unsuitable for application as coolant pumps, it is an object of the present invention to provide an electric screw pump suitable for delivering aggressive liquid media and providing cooling of electric transmissions.

Another partial aspect of said object further provides a corresponding technical solution so that it can also be produced in large quantities at low cost by mass production.

This object is achieved by the features of claim 1 . The electric screw coolant pump for delivering coolant circulation according to the invention is notably characterized in that the motor housing comprises a motor chamber in which a dry-running electric motor is arranged such that it is delimited with respect to the delivery flow; And the motor housing includes a heat transfer section through which the delivery flow flows, the heat transfer section being disposed between the motor cavity and an assembly boundary between the motor housing and the spindle housing.

Thus, the invention provides for the first time a screw pump as a coolant pump.

Furthermore, the present invention provides for the first time a screw pump as an electric liquid pump driven by a dry-running electric motor.

Furthermore, the present invention provides for the first time a screw pump as an electric liquid pump in which a convective assisted heat transfer is achieved from the dry motor chamber to the delivery flow of the liquid medium to be delivered.

The invention allows the production of coolant pumps at high power density levels. Progressive cavity pumps offer the high delivery pressure of positive displacement pumps, but with relatively low pulsation similar to centrifugal pumps. Combined with the electric drive, the progressive cavity pumps allow universal installation and application. The electric screw coolant pump according to the invention is suitable for use, for example, in electric (battery electric) vehicles, where no mechanical drive source is provided and thin or capillary cooling ducts in battery modules or traction motors The branched structure requires high delivery pressure.

From a constructional point of view, the invention is based on the principle of shifting the axial position of the assembly boundary between the motor housing and the spindle housing further from the conventional functional position in the direction of the spindle chamber. In this way, on the one hand, an area is provided which is protected from the liquid of the delivery flow, and thus the electric drive is not subjected to corrosion. On the other hand, due to the heat transfer section, a liquid carrying area on the motor housing is provided, which increases the internal thermal contact surface with the coolant. Waste heat from power dissipation can be efficiently carried away from the pump by convective heat exchange of the thermally conductive motor case and delivery flow thus created at the thermal contact surfaces, even at relatively low temperature differentials between the electric drive and the coolant. The same goes for hours.

The increase in thermal contact surface is achieved without increasing the complexity of the structure (eg, in the form of surface-enhancing structures, flow resistance members, etc.). The motor housing is designed as a casting during product development. Changed component boundaries can thus be produced on the pump configuration according to the invention without incurring considerable outlay or increasing manufacturing costs. Due to the complementary shifting of the assembly boundaries of the main shaft housing, even an increase in the axial dimension of the motor housing generally does not cause a detrimental increase in the overall size of the pump.

Flow losses in the pump are significantly reduced compared to known pump configurations with wet running electric drives exposed to the delivery flow.

The above-mentioned shifting of the component boundaries creates an open spindle chamber cross-section at the end of the spindle housing. Thus, the screw spindle can simply be inserted through the open end of the spindle chamber during pump assembly.

Advantageous developments of the invention are provided in the dependent claims.

According to an aspect of the invention, the heat transfer section may further comprise a pump outlet. In this way, the flow cross-section of the entire delivery flow can be passed through the motor chamber. The inner surface of the pump outlet at the heat transfer section further increases the thermal contact surface of the thermally conductive motor housing with the delivered flow to a considerable extent.

According to one aspect of the invention, the heat transfer section may comprise a delivery flow chamber that creates a connection between the front delimitation of the motor chamber and the spindle chamber. With this design, the heat transfer portion of the thermally conductive motor housing between the electric heat source in the motor cavity and the delivery flow is further shortened. Furthermore, the inner surface of the delivery flow chamber in the heat transfer section further increases the thermal contact surface of the thermally conductive motor housing with the delivery flow.

According to an aspect of the invention, the heat transfer section may comprise a bearing seat of a shaft bearing arranged between the electric motor and the screw spindle. The surface of the bearing seat in the heat transfer section in turn increases the thermal contact surface of the thermally conductive motor housing with the delivery flow. Furthermore, the integration of the shaft bearing in the axial region of the heat transfer section is advantageous for the compact construction of the pump.

According to an aspect of the invention, the electronic system for the electric motor may also be arranged in the motor chamber. Therefore, another source of heat is incorporated into the inventive cooling of the electric drive. In this way, power dissipation from the power electronics is also vented via the delivery flow.

According to an aspect of the invention, the stator in the motor housing and/or the electronics of the electric motor can be in contact with the front delimitation of the motor chamber. Thus, the smallest possible heat transfer portion of the thermally conductive motor housing between the electrodynamic heat source in the motor cavity and the delivery flow is ensured.

According to an aspect of the present invention, the heat transfer section may be integrally formed with the motor housing. In this way, the lowest possible production costs for an optimized heat transfer part and motor housing without boundary surfaces or joints in the material are ensured.

According to an aspect of the present invention, the spindle housing may be formed in one piece. As explained above, the displacement of the assembly boundary between the motor housing and the spindle housing creates an open cross-section for the spindle chamber. In this way, neither the assembly of the pump nor the production of the molded body of the main shaft housing requires a division into two housing halves. The one-piece design of the spindle housing ensures a joint-free internal contour of the spindle chamber without post-processing. The inner contour of the spindle chamber can be produced simply and precisely by drilling.

According to an aspect of the invention, the spindle housing may include a pump inlet. The spindle housing is designed as a casting during product development. Thus, through the integration of the pump inlet, the number of components of a pump construction according to the invention can be reduced without considerable outlay.

According to one aspect of the invention, a flange joint consisting of a flange section of the motor housing and a flange section of the spindle housing may be formed at an assembly boundary between the motor housing and the spindle housing. The flanged joint permits a preferred threaded connection for assembling the two housing components, while the corresponding flanged planes allow different types of sealing.

Description of drawings

The invention will be elucidated hereinafter with the aid of examples and with reference to the accompanying drawings,

Figure 1 shows a schematic sectional view through a screw coolant pump according to one embodiment of the invention.

Detailed ways

According to the present disclosure, the term "screw pump" is understood to mean a skewed rotary piston pump with a displaced screw pitch for the medium to be delivered. Pumps of this type generally comprise a driven screw main shaft 2a, and at least one further screw main shaft 2b in joint movement therewith via toothed engagement.

In the schematically illustrated embodiment of FIG. 1 , in the spindle housing 1 , the driven screw spindle 2 a and the screw spindle 2 b in joint motion are received in a spindle chamber 10 of the spindle housing 1 in a rotatably mounted manner. middle. The spindle chamber 10 has a cross-sectional profile in the form of a so-called figure-of-eight housing, i.e. it is formed by two holes in the pump housing 1 with overlapping radii in order to secure the screw spindle 2a, 2b meshing. The driven screw spindle 2 a is connected to an electric motor 4 .

The pressure side of the spindle chamber 10 , which communicates with the pump outlet 13 in the form of a pressure connection, is located on the drive side of the screw spindles 2 a , 2 b. The suction side of the spindle chamber 10 is located on the other side of the screw spindles 2 a , 2 b , opposite the electric motor 4 . The suction side of the spindle chamber 10 communicates with the pump inlet 11 in the form of a suction connection. With respect to the delivery direction of the screw pump, the liquid medium or coolant to be delivered is drawn on the suction side from the coolant circuit through the pump inlet 11 into the spindle chamber 10 . The rotational movement of the intermeshing screw configuration of the rotating screw spindles 2a, 2b generates a negative pressure on the suction side of the spindle chamber 10 and a positive pressure on the opposite pressure side of the spindle chamber 10. The medium to be delivered is delivered by continuous displacement along the pitch of the intermeshing screw configuration and is ejected from the spindle chamber 10 via the pump outlet 13 .

The motor housing 3 adjoins the spindle housing on the pressure side of the spindle chamber 10 . The motor housing 3 includes a flange section 35 formed to match the flange section 15 of the spindle housing 1 . Flange joints are sealed by seals. A separate motor chamber 30 is formed in the motor housing 3, in which chamber the dry-running electric motor 4 and the electronics (to be exact, power electronics, not shown) for switching the electric power at the electric motor are received. ). The open end of the motor chamber 30 is closed by a motor cover (not shown). A collar-shaped bearing seat 32 with a through hole in the front delimitation of the motor chamber 30 is formed in the motor housing 3 . The common shaft bearing 23 of the electric motor 4 and the driven screw spindle 2 a fits in a bearing housing 32 . Upstream of the shaft bearing 23, a shaft seal 34 fits into the bearing housing 32 and seals the motor chamber 30 against the ingress of liquid.

The dry running electric motor 4 is of the inner rotor type with an inner rotor 42 and an outer stator 41 . The rotor 42 is coupled to the driven screw spindle 2a. The stator 41 comprises field coils which are actuated by power electronics and supplied with electrical power. The stator 41 of the electric motor 4 is in thermal contact with the inner peripheral surface of the motor chamber 30 and with the front boundary surface, and thus waste heat from the field coils of the stator 41 is transferred to the motor housing 3 .

The motor housing 3 is composed of a metal material having a good thermal conductivity level, such as an aluminum cast alloy, and is formed as an integral casting. The heat transfer section 31 of the motor housing 3 extends in an axial section between the motor chamber 30 and the flange section 35 . As an integral component of the heat transfer section 31 , the pump outlet 13 in the form of a radial discharge pressure connection is arranged between the motor chamber 30 and the spindle chamber 10 . A delivery flow chamber 33 is formed in the heat transfer section 31 and through which the liquid medium to be delivered flows. The delivery flow chamber 33 creates a connection of the pump's delivery flow between the pressure side of the spindle chamber 10 and the pump outlet 13 . The delivery flow chamber 33 surrounds the collar-shaped bearing seat 32 and carries the pressurized liquid medium to be delivered to the front delimitation of the motor chamber 30 in thermal contact with the stator 41 .

The heat transfer section 31 constitutes a volume of thermally conductive material on the motor housing 3 which positively participates in the dissipation of waste heat from the motor chamber 30 into the delivery flow. The inner surface of the pump outlet 13 , the inner surface of the delivery flow chamber 33 and the surface of the bearing housing 32 each contribute to increasing the thermal contact surface between the motor chamber 30 and the delivery flow within the heat transfer section 31 .

The optimized heat transfer limits any temperature difference between the coolant and the motor chamber 30 . Thus, even at high loads and high operating temperatures in the coolant circuit, critical component temperatures of the electrical drive are reliably prevented at which overheating damage could occur on the stator 41 or on the winding insulation of the electronic system.

List of reference numerals:

1 Spindle housing

2a driven screw spindle

2b Screw spindles in joint motion

3 Motor housing

4 electric motors

10 Spindle chamber

11 Pump inlet

13 Pump outlet

15 Flange section of the spindle housing

23 Shaft bearing

30 Motor chamber

31 heat transfer section

32 bearing housing

33 Delivery flow chamber

34 shaft seal

35 Flange section of motor housing

41 Stator

42 rotor

Claims (9)

1. An electric screw coolant pump for delivering a coolant cycle, comprising:

a spindle housing (1) having a spindle chamber (10) in which at least two screw spindles (2 a, 2 b) are rotatably accommodated;

a pump inlet (11) and a pump outlet (13) for guiding a delivery flow through the spindle chamber (10);

-a motor housing (3) axially arranged adjacent to the spindle housing (1);

is characterized in that

The motor housing (3) comprises a motor chamber (30) in which a dry running electric motor (4) is arranged such that it is delimited with respect to the delivery flow; and

the motor housing (3) comprises a heat transfer section (31) through which the delivery flow flows, which is arranged between the motor chamber (30) and an assembly boundary between the motor housing (3) and the spindle housing (1).

2. Electric screw coolant pump according to claim 1, characterized in that,

the heat transfer section (31) further comprises the pump outlet (13).

3. Electric screw coolant pump according to claim 1 or 2, characterized in that,

the heat transfer section (31) includes a delivery flow chamber (33) establishing a connection between a front delimitation of the motor chamber (30) and the spindle chamber (10).

4. Electric screw coolant pump according to any of the preceding claims, characterized in that,

the heat transfer section (31) comprises a bearing seat (32) of a shaft bearing (23) arranged between the electric motor (4) and the screw spindle (2 a, 2 b).

5. Electric screw coolant pump according to any of the preceding claims, characterized in that,

an electronic system for the electric motor (4) is also arranged inside the motor chamber (30).

6. Electric screw coolant pump according to any of the preceding claims, characterized in that,

the stator (41) and/or the electronics of the electric motor (4) are in contact with the front delimitation of the motor chamber (30) inside the motor housing (3).

7. Electric screw coolant pump according to any of the preceding claims, characterized in that,

the heat transfer section (31) is integrally formed with the motor housing (3).

8. Electric screw coolant pump according to any of the preceding claims, characterized in that,

the spindle housing (1) is formed as one piece.

9. Electric screw coolant pump according to any of the preceding claims, characterized in that,

at the assembly boundary between the motor housing (3) and the spindle housing (1), a flange joint is formed by a flange section (35) of the motor housing (3) and a flange section (15) of the spindle housing (1).

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