CN113227580B

CN113227580B - Electric screw coolant pump

Info

Publication number: CN113227580B
Application number: CN201980085411.6A
Authority: CN
Inventors: 丹尼尔·德勒; 弗朗茨·帕维勒克
Original assignee: Nidec GPM GmbH
Current assignee: Nidec GPM GmbH
Priority date: 2019-02-12
Filing date: 2019-12-09
Publication date: 2023-06-27
Anticipated expiration: 2039-12-09
Also published as: DE102019103470A1; US20220099088A1; EP3924624A1; CN113227580A; BR112021012370A2; WO2020164776A1; EP3924624B1

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 circulation or the like, in particular for delivering corrosive liquid media.

Background

Screw pumps are positive displacement pumps that allow for high pressure and high volumetric efficiency. They do not provide adjustment of geometry 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. Thus, mechanically driven screw pumps have so far been mainly used in large scale applications, such as oil pumps in stationary installations or ship engines, which run at a relatively constant operating point.

In the field of fuel delivery pumps for vehicles, smaller electrically driven screw pumps are recently known, which allow higher pressures than centrifugal pumps. These pumps are installed in a submerged arrangement in a vehicle tank and provide a high input pressure upstream of a 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 separate tank, and thus both the rotor and 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, transmissions that become hot due to power dissipation are easily cooled in such 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 screw pump. An electric motor is received in the outlet chamber of the cover and fuel flows through the electric motor before exiting the outlet.

DE102015101443B3 describes a fuel pump with a housing, wherein an electric drive motor is coupled to a screw pump. The fuel flows through the drive motor before exiting the pressure side outlet.

WO2014/138519A1 describes an electric liquid pump of the screw type. The liquid flowing through the inlet and outlet also surrounds the motor. The fuel is mentioned as liquid. The flange plane shown in the illustrated configuration between the motor-side housing portion and the pump-side housing portion extends between the motor and the pump-side outlet.

DE102017210771A1 describes an electrically driven screw pump as a fuel delivery assembly. The pump housing and the electric motor are received in the sleeve. In the illustrated embodiment, which does not include a separate tank on the stator of the electric motor, the electric components of the motor are in direct contact with the fuel in the outlet guide on the pressure side of the spindle chamber.

However, the above-mentioned pumps cannot be put to use as electric water pumps, rather as electric coolant pumps. Liquid media, such as coolant, waiting to be delivered can corrosively damage exposed components of the electric motor, particularly the coil windings of the stator.

US6,371,744B1 describes an electric vacuum pump of the screw type. The screw spindle is driven by an electric motor arranged in a separate housing.

Independently of the specific modification between the screw pump for gas and the screw pump for liquid, the vacuum pump cannot be put into use as an electric coolant pump. With the arrangement shown, adequate cooling of the dry running electric motor is not ensured. In a pressurized coolant loop, the target temperature of the coolant may be near the boiling temperature of the coolant. In this case, overheat damage to the electric or electronic components will occur in continuous operation.

Disclosure of Invention

Based on the known electric screw pumps of the prior art which are not suitable for application as coolant pumps, it is an object of the present invention to provide an electric screw pump which is suitable for delivering corrosive liquid medium and which provides cooling of an electric drive.

Another part of the object is to further provide a corresponding technical solution so that it can be mass-produced at low cost by mass production.

The object is achieved by the features of claim 1. The electric screw coolant pump for delivering a coolant circulation according to the invention is characterized in particular in that the motor housing comprises a motor chamber in which the 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 disposed between the motor chamber and an assembly boundary between the motor housing and the spindle housing.

The present invention therefore provides for the first time a screw pump as 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, wherein a convection-assisted heat transfer of the delivery flow from the dry motor chamber to the liquid medium to be delivered is achieved.

The invention permits the production of coolant pumps at high power density levels. Screw pumps provide high delivery pressures for positive displacement pumps, but have relatively low pulsations similar to centrifugal pumps. In conjunction with the electrical drive, the screw pump permits universal installation and application. The electric screw coolant pump according to the invention is suitable for use, for example, in electric (in particular battery electric) vehicles, in which no mechanical drive source is provided and the branching structure of the thin or capillary cooling ducts in the battery module or traction motor requires a high delivery pressure.

From a constructional point of view, the invention is based on the principle of further shifting the axial position of the assembly boundary between the motor housing and the spindle housing from the normal functional position in the direction of the spindle chamber. In this way, on the one hand, a zone is provided that is protected from the liquid of the delivery flow, and thus the electric drive is not subject to corrosive effects. 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 the power dissipation can be effectively carried away from the pump by convective heat exchange of the thermally conductive motor housing thus generated with the delivery flow at the thermal contact surface, even when the temperature difference between the electric drive and the coolant is small.

The increase in the thermal contact surface is achieved without increasing the complexity of the structure (e.g., in the form of surface increasing structures, flow resistance members, etc.). The motor housing is designed as a casting during product development. Thus, a modified assembly boundary can be created on the pump construction according to the invention without incurring considerable expense or increasing manufacturing costs. By shifting the assembly boundaries of the spindle housing in a complementary manner, even if the axial dimension of the motor housing is increased, no detrimental increase in the overall size of the pump is substantially caused.

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

The above mentioned displacement of the assembly boundary creates an open spindle chamber cross section at the end of the spindle housing. Thus, the screw spindle may 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 one 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 penetrated 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 delivery flow to a substantial extent.

According to one aspect of the invention, the heat transfer section may comprise a delivery flow chamber creating 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 electrical heat source and the delivery flow in the motor chamber 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 one aspect of the invention, the heat transfer section may comprise a bearing housing of a shaft bearing arranged between the electric motor and the screw spindle. The surface of the bearing housing 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 a compact construction of the pump.

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

According to one aspect of the invention, the stator in the motor housing and/or the electronic system of the electric motor may 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 electrical heat source and the delivery flow in the motor chamber is ensured.

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

According to one aspect of the invention, the spindle housing may be formed as 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, no division into two housing halves is required for the assembly of the pump and the production of the molded body of the spindle housing. The unitary design of the spindle housing ensures a contactless interior profile of the spindle chamber without requiring post-processing. The internal profile of the spindle chamber can be produced simply and precisely by drilling.

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

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 flange joint permits a preferably threaded connection for assembling the two housing components, while the corresponding flange plane allows for different types of seals.

Drawings

The invention will be elucidated hereinafter with the aid of an embodiment and with reference to the accompanying drawing,

fig. 1 shows a schematic cross-section through a screw coolant pump according to an embodiment of the invention.

Detailed Description

In accordance with the present disclosure, the term "screw pump" is understood to mean a skewed rotary piston pump having a pitch for displacement of the medium to be delivered. Pumps of this type generally comprise a driven screw spindle 2a and at least one further screw spindle 2b which moves in conjunction therewith via toothed engagement.

In the schematically illustrated embodiment of fig. 1, in the spindle housing 1, the driven screw spindle 2a and the screw spindle 2b in joint movement are received in a rotatably mounted manner in a spindle chamber 10 of the spindle housing 1. The spindle chamber 10 has a cross-sectional profile in the form of a so-called figure-of-the-eye (figure-of-the-eye) housing, i.e. it is formed by two holes with overlapping radii in the pump housing 1 in order to ensure engagement of the screw spindles 2a, 2b. The driven screw spindle 2a 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 2a, 2b. The suction side of the spindle chamber 10 is located on the other side of the screw spindle 2a, 2b, 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 into the spindle chamber 10 on the suction side from the coolant circulation through the pump inlet 11. The rotational movement of the intermeshing screw configuration of the rotating screw spindles 2a, 2b creates 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 a continuous displacement along the pitch of the intermeshing screw configuration and is ejected from the spindle chamber 10 via pump outlet 13.

The motor housing 3 adjoins the spindle housing on the pressure side of the spindle chamber 10. The motor housing 3 comprises a flange section 35 formed to mate with the flange section 15 of the spindle housing 1. The flange joint is sealed by a seal. A separate motor chamber 30 is formed in the motor housing 3, in which chamber a dry running electric motor 4 for switching the power at the electric motor and an electronic system (in particular, power electronics, not shown) 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 2a is fitted 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 having 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 heat conduction level, such as an aluminum casting alloy, and is formed as a one-piece 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 within the heat transfer section 31, and the liquid medium to be delivered flows there through. The delivery flow chamber 33 creates a connection of the delivery flow of the pump 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 that definitively 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 help to increase 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. Therefore, even at high loads in the coolant circulation and high operating temperatures, critical component temperatures of the electric transmission, at which overheating damage may occur on the stator 41 or on the winding insulation of the electronic system, are reliably prevented.

List of reference numerals:

1. main shaft shell

2a driven screw spindle

2b in a combined movement

3. Motor shell

4. Electric motor

10. Spindle chamber

11. Pump inlet

13. Pump outlet

15. Flange section of spindle housing

23. Shaft lever bearing

30. Motor chamber

31. Heat transfer section

32. Bearing pedestal

33. Delivery flow chamber

34. Shaft seal

35. Flange section of motor housing

41. Stator

42. Rotor

Claims

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).