ELECTRICAL SCREW SPINDLE COOLANT PUMP

Abstract

An electrical screw spindle coolant pump is suitable for conveying a coolant circuit or other corrosive, liquid media. The electrical screw spindle coolant pump has a spindle housing with a spindle chamber and an axially adjacent motor housing. The motor housing has a motor chamber, in which a dry-running electric motor is arranged separated from the flow current. The motor housing has a thermal transition portion through which the flow current flows. The thermal transition portion is arranged between the motor chamber and a component boundary of the motor housing to the spindle housing.

Claims

1. An electric screw coolant pump for delivering a coolant circulation comprising: a spindle housing having a spindle chamber in which at least two screw spindles are rotatably accommodated; a pump inlet and a pump outlet for guiding a delivery flow through the spindle chamber; a motor housing arranged axially adjacent to the spindle housing; wherein the motor housing includes a motor chamber in which a dry-running electric motor is arranged so the motor chamber is delimited with respect to the delivery flow; and the motor housing comprises a heat transfer section, through which the delivery flow flows, arranged between the motor chamber and a component boundary between the motor housing and the spindle housing.

2. The electric screw coolant pump according to claim 1, wherein the heat transfer section includes the pump outlet.

3. The electric screw coolant pump according to claim 1, wherein the heat transfer section includes a delivery flow chamber that establishes a connection between a frontal delimitation of the motor chamber and the spindle chamber.

4. The electric screw coolant pump according to claim 1, wherein the heat transfer section includes a bearing seat for a shaft bearing arranged between the electric motor and the screw spindles.

5. The electric screw coolant pump according to claim 1, wherein an electronic system for the electric motor is arranged inside the motor chamber.

6. The electric screw coolant pump according to claim 1, wherein a stator and/or an electronic system of the electric motor is in contact with a frontal delimitation of the motor chamber inside the motor housing.

7. The electric screw coolant pump according to claim 1, wherein the heat transfer section is formed integrally with the motor housing.

8. The electric screw coolant pump according to claim 1, wherein the spindle housing is formed as one piece.

9. The electric screw coolant pump according to claim 1, wherein at the component boundary between the motor housing and the spindle housing, a flange joint is formed of a flange section of the motor housing and a flange section of the spindle housing.

Description

[0032] The invention will be explained hereinafter with the aid of an embodiment and with reference to the accompanying drawing,

[0033] FIG. 1 shows a schematic sectional view through a screw coolant pump according to one embodiment of the invention.

[0034] In terms of this disclosure, the term ‘screw pump’ is understood to mean skew rotary piston pumps with a thread pitch for displacement of the medium to be delivered. Such types of pump generally comprise a driven screw spindle 2a and at least one further screw spindle 2b which is in coupled motion therewith via engagement of the toothing.

[0035] In the embodiment of the schematic illustration of FIG. 1, in a spindle housing 1, a driven screw spindle 2a and a screw spindle 2b in coupled motion 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 contour in the form of a so-called figure-of-eight housing, i.e. it is formed by two bores in the pump housing 1 with overlapping radii in order to ensure engagement of the screw spindles 2a, 2b. The driven screw spindle 2a is connected to an electric motor 4.

[0036] A pressure side of the spindle chamber 10 which communicates with a pump outlet 13 in the form of a pressure connection is located on the drive side of the screw spindles 2a, 2b. A suction side of the spindle chamber 10 is located on the other side of the screw spindles 2a, 2b opposite the electric motor 4. The suction side of the spindle chamber 10 communicates with a pump inlet 11 in the form of a suction connection. In relation to the delivery direction of the screw pump, a liquid medium to be delivered or a coolant is drawn into the spindle chamber 10 from a coolant circulation through the pump inlet 11 on the suction side. A rotational movement of engaged screw profiles 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 opposing pressure side of the spindle chamber 10. The medium to be delivered is delivered by continuous displacement along a screw pitch of the engaged screw profiles and ejected from the spindle chamber 10 through the pump outlet 13.

[0037] A 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 which is formed to match a flange section 15 of the spindle housing 1. The flange joint is sealed by a seal. A separated motor chamber 30 is formed in the motor housing 3, in which chamber the dry-running electric motor 4 and an electronic system, in particular power electronics (not shown), for switching the electric power at the electric motor are received. An open end of the motor chamber 30 is closed by a motor cover (not shown). A collar-shaped bearing seat 32 with a though-opening in a frontal delimitation of the motor chamber 30 is formed in the motor housing 3. A common shaft bearing 23 of the electric motor 4 and of the driven screw spindle 2a is fitted in the bearing seat 32. Upstream of the shaft bearing 23, a shaft seal 34 is fitted into the bearing seat 32 and seals the motor chamber 30 against ingress of liquid.

[0038] The dry-running electric motor 4 is of the internal rotor type with an internal rotor 42 and an external stator 41. The rotor 42 is coupled to the driven screw spindle 2a. The stator 41 comprises field coils which are actuated by the power electronics and supplied with electric power. The stator 41 of the electric motor 4 is in thermal contact with an internal peripheral surface and with a frontal boundary surface of the motor chamber 30, and so waste heat from the field coils of the stator 41 is transferred to the motor housing 3.

[0039] The motor housing 3 consists of a metallic material with a good level of heat conductivity, such as an aluminium cast alloy, and is formed as a one-piece cast part. A 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 radially discharging 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 has the liquid medium to be delivered flowing through it. The delivery flow chamber 33 produces a connection for 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 pressurised liquid medium to be delivered to the frontal delimitation of the motor chamber 30, with which the stator 41 is in thermal contact.

[0040] The heat transfer section 31 constitutes the region of the heat-conducting material volume on the motor housing 3 which is definitively involved in the dissipation of waste heat from the motor chamber 30 into the delivery flow. The internal surface of the pump outlet 13, the internal surface of the delivery flow chamber 33 and the surface of the bearing seat 32 each contribute to enlargement of the thermal contact surface between the motor chamber 30 and the delivery flow within the heat transfer section 31.

[0041] The optimised heat transfer limits any temperature difference between a coolant and the motor chamber 30. Consequently, even under high loading with a high operating temperature in a coolant circulation, a critical component temperature of the electric drive, at which overheating damage can occur on the winding insulations of the stator 41 or the electronic system, is reliably prevented.

LIST OF REFERENCE NUMERALS

[0042] 1 Spindle housing

[0043] 2a Driven screw spindle

[0044] 2b Screw spindle in coupled motion

[0045] 3 Motor housing

[0046] 4 Electric motor

[0047] 10 Spindle chamber

[0048] 11 Pump inlet

[0049] 13 Pump outlet

[0050] 15 Flange section of the spindle housing

[0051] 23 Shaft bearing

[0052] 30 Motor chamber

[0053] 31 Heat transfer section

[0054] 32 Bearing seat

[0055] 33 Delivery flow chamber

[0056] 34 Shaft seal

[0057] 35 Flange section of the motor housing

[0058] 41 Stator

[0059] 42 Rotor