Variable mechanical automotive coolant pump

Abstract

The invention relates to a variable mechanical motor vehicle coolant pump (10) comprising a rotatable impeller (20) which is jointly rotatably connected to a rotatable rotor shaft (30). The coolant pump further comprises a non-rotatable control sleeve (40) having a hollow cylindrical control sleeve body (45) which is axially slidably guided within a stationary guide cylinder (70) for adjusting the flow rate of the variable mechanical motor vehicle coolant pump (10) by closing or opening a discharge radial outer side (21) of the impeller (20). The coolant pump is further provided with at least one separate guide means (60) guiding a radial outer side (42) of the control sleeve (40) within the stationary guide cylinder (70). Thus, wear between the control sleeve (40) and the stationary guide cylinder (70) is reduced and the friction pairing of the sliding surfaces can be individually selected.

Description

Technical Field

[0001] This invention relates to a variable mechanical automotive coolant pump. Background Technology

[0002] A coolant pump is used to provide and regulate the flow of coolant to cool an internal combustion engine, thereby preventing engine components from overheating. The coolant pump is mechanically connected to the crankshaft of the internal combustion engine, for example, via a belt drive. Due to a constant transmission ratio, the rotational speed of the coolant pump rotor is always proportional to the crankshaft speed, rather than to the cooling performance requirements of the internal combustion engine. Therefore, variable mechanical coolant pumps are becoming increasingly common in automobiles.

[0003] One type of variable mechanical automotive coolant pump is equipped with a switchable clutch to disconnect the pump's drive shaft from a belt drive driven by the internal combustion engine crankshaft when coolant circulation is not required.

[0004] WO 2019 / 042530 A1 discloses an alternative pump type for a variable mechanical automotive coolant pump, which has an axially sliding control sleeve with a defined valve. To reduce pump flow, the axially sliding control sleeve can close the radial discharge region of an impeller within the pump, which is mechanically driven by the crankshaft of an internal combustion engine via a belt drive. Depending on the desired coolant flow rate, a hollow cylindrical control sleeve can be pushed onto the impeller, covering the impeller's radial discharge region. Using this control sleeve, the impeller's radial discharge region can also be completely closed to hydraulically shut off the coolant pump during engine cold starts.

[0005] The control sleeve is actuated by a hydraulic actuation system supplied with pressurized coolant from the pumping chamber. Leakage between the outer cylindrical surface of the control sleeve and the inner cylindrical surface of the guide cylinder must be extremely low to ensure a constant pressure level within the hydraulic control chamber. Therefore, a small hydraulic clearance between the contact surfaces is necessary. Consequently, the manufacturing precision requirements for the control sleeve and guide cylinder are very high, leading to high production costs for the components.

[0006] Due to high precision requirements, the control sleeve is made of metal. The guide cylinder inside the pump housing is also made of metal, resulting in significant wear between the machined metal contact surfaces. Inaccurate guidance of the control sleeve can cause it to tilt within the guide cylinder, further increasing wear. This tilting can be caused by factors such as pressure fluctuations, contaminating particles in the coolant, or inaccurate manufacturing processes affecting the contact surfaces of components.

[0007] To reduce wear, the inner cylinder surface of the guide cylinder and the outer cylinder surface of the control sleeve are provided with a wear-resistant coating.

[0008] The high precision requirements and additional wear-resistant coatings result in high production costs for coolant pumps. Summary of the Invention

[0009] One object of the present invention is to provide a cost-effective and reliable automotive coolant pump.

[0010] This objective is achieved through a variable mechanical automotive coolant pump.

[0011] The variable mechanical automotive coolant pump according to the invention is provided with a rotatable impeller that is rotatably connected to a rotatable rotor shaft, which is mechanically driven, for example, by a belt drive of an internal combustion engine.

[0012] The variable mechanical automotive coolant pump according to the invention is further provided with a non-rotatable and axially slidable control sleeve having a hollow cylindrical control sleeve body guided by and located within a static guide cylinder, which is, for example, machined and defined within a cast static pump housing.

[0013] According to the present invention, the variable mechanical automotive coolant pump is provided with separate means that guide a slidable control sleeve within the inner cylindrical surface of a static guide cylinder. The means surround the outer cylindrical surface of the control sleeve substantially around its entire circumference, such that the outer cylindrical surface of the control sleeve does not directly contact the inner cylindrical surface of the static guide cylinder.

[0014] Preferably, the radial extension of the generally cylindrical gap between the outer cylindrical surface of the control sleeve and the inner cylindrical surface of the static guide cylinder is at least 0.5 mm.

[0015] By applying individual guide devices, the friction pairing between the sliding surface of the static guide cylinder and the guide device is freely selectable, allowing both the control sleeve and the guide device to be optimally materialized according to their respective functions. For example, a plastic guide device providing low friction and high sealing properties can be combined with a metal control sleeve offering high strength and high shape stability.

[0016] In a preferred embodiment of the present invention, the axial position of the control sleeve for adjusting the impeller discharge velocity is continuously adaptable.

[0017] The actuation of the control sleeve can be achieved through different types of actuation systems, and a hydraulic actuation system is preferably provided. The hydraulic actuation system is equipped with a hydraulic control chamber that is fluidly effective on the axial end face of the control sleeve. Hydraulic pressure axially pushes the control sleeve on the impeller, thereby closing the radial discharge area of ​​the impeller. The high hydraulic pressure used for the hydraulically actuated control sleeve is preferably provided by an additional side-channel pump rotor assembly located behind the impeller. Due to this high hydraulic pressure, the control quality of the hydraulic control chamber depends essentially on the sealing quality of the individual guide devices; therefore, the hydraulic quality of the guide devices is crucial for the precise hydraulic actuation of the control slider.

[0018] The return mechanism of the control sleeve can be implemented either by a spring-supported return mechanism or by providing a second hydraulic control chamber, which is defined, for example, by an internal static support device and an axial end face on the opposite side of the first axial end face of the control sleeve. Therefore, the pump can be purely hydraulically driven, thus eliminating the need for an additional electric motor to provide high driving force.

[0019] In a preferred embodiment of the invention, the guiding device is defined by a non-enclosed annular guiding device body having a compensating slit. This compensating slit allows the total circumference of the annular guiding device body to accommodate geometric inaccuracies of the sliding surface. To balance tolerance-related inequalities, the shape and dimensions of the guiding device body can be adapted to the shape and dimensions of the inner guiding cylinder surface. The compensating slit also allows for adaptation to geometric changes caused by differences in thermal expansion between the control sleeve and the static guiding cylinder.

[0020] In a preferred embodiment of the invention, the axial extension of the guide device is less than 25% of the total axial extension of the control sleeve, such that the control sleeve is not guided across the entire surface of the outer cylinder. This results in a reduction of the sliding contact surface, thereby reducing friction between the guide device and the static guide cylinder. Low friction allows for relatively low hydraulic actuation force, reducing power consumption of the coolant pump's actuation system and increasing pump efficiency. Furthermore, the lower hydraulic actuation force results in lower hydraulic pressure in the hydraulic control chamber, which increases the sealing efficiency of the guide device and reduces leakage on the guide device.

[0021] In a preferred embodiment of the invention, the control sleeve is guided by two separate guide devices, and preferably exactly by two guide devices, to provide a statically defined system with one degree of freedom in the sliding direction. The guide devices are preferably arranged such that they are spaced apart from each other by at least one axial extension of the guide device. The use of two spaced-apart guide devices avoids any associated tilting of the control sleeve within the statically guided cylinder.

[0022] Preferably, the guide device body is provided with a labyrinthine compensating slit. This labyrinthine compensating slit includes two axially oriented slit portions, each extending from two axial end faces of the guide device body, and a circumferentially oriented slit portion connecting the two axially oriented slit portions. The slit width of the circumferentially oriented slit portion is very small to avoid associated coolant leakage on the guide device. The slit width of the circumferentially oriented slit portion can also be substantially zero. The slit width of the axially oriented slit portion is greater than the slit width of the circumferentially oriented slit portion to allow the annular guide device body to accommodate manufacturing inaccuracies and differences in thermal expansion between the control sleeve and the static guide cylinder.

[0023] In a preferred embodiment of the invention, the guide device is embedded in the control sleeve body. To secure the guide device, the control sleeve body preferably has an annular groove on its outer cylindrical surface. The guide device body extends radially beyond the outer cylindrical surface of the control sleeve by at least 20% of its radial thickness, such that the guide device is not fully embedded in the control sleeve. This prevents the control sleeve from contacting the static guide cylinder. The bottom surface of the groove radially supports the guide device, and the sidewalls of the groove prevent the guide device from sliding axially along the outer cylindrical surface of the control sleeve. The sidewalls of the groove also improve sealing efficiency by providing an additional labyrinthine gap between the guide device and the groove surface in the axial direction. Because the guide device adapts to the inner cylindrical surface of the guide cylinder, the sealing efficiency is ensured by the sidewalls of the groove even if the guide device does not fully contact the bottom surface of the groove.

[0024] In a preferred embodiment of the invention, the guiding device is made of a plastic material. Many plastic materials are characterized by good sliding properties and a low coefficient of friction when combined with metallic materials, which reduces sliding friction and wear on the sliding contact surfaces of the components. The good sliding properties of the plastic guiding device also result in low hydraulic actuation force, thus reducing the hydraulic pressure in the hydraulic control chamber.

[0025] Many plastic materials possess high elastic deformation capacity, allowing plastic guide devices to easily adapt to the shape and size of the inner cylindrical surface of a static guide cylinder, thereby improving guiding quality and sealing efficiency. Consequently, the manufacturing precision of the static guide cylinder can be reduced, thus saving on the production cost of the coolant pump.

[0026] The use of plastic guide devices instead of costly wear-resistant coatings, combined with lower manufacturing precision requirements, significantly improves the cost efficiency of the coolant pump manufacturing process.

[0027] In a preferred embodiment of the invention, the slidable control sleeve is made of an aluminum-based material. Aluminum-based materials are characterized by low density, resulting in light weight, which reduces the weight of the coolant pump. Aluminum-based materials also possess high strength and high shape stability. Attached Figure Description

[0028] Embodiments of the present invention are described with reference to the accompanying drawings, in which:

[0029] Figure 1 A schematic longitudinal cross-sectional view of a variable mechanical automotive coolant pump including a control sleeve according to the invention is shown, and

[0030] Figure 2 It shows Figure 1 A schematic perspective view of the control sleeve. Detailed Implementation

[0031] Figure 1A variable mechanical automotive coolant pump 10 is shown, for example, for supplying liquid coolant to an internal combustion engine. The coolant pump 10 includes an impeller 20 rotatably connected to a rotor shaft 30. The rotor shaft 30 is driven, for example, by a belt drive of the internal combustion engine. The coolant pump 10 also includes a non-rotatable and axially slidable control sleeve 40. The hollow cylindrical control sleeve body 45 includes two separate plastic guides 60, 60', each defined by a non-enclosed annular guide body 61. The guide body 61 slidably supports the control sleeve 40 within and at a static guide cylinder 70. The coolant pump 10 also includes a static inner support cylinder 50 guiding the radial interior of the control sleeve 40.

[0032] Impeller 20 is arranged within pumping chamber 25 and includes a disc-shaped impeller body 22 having a plurality of integrally formed impeller blades 26 arranged substantially radially in a fan-shaped configuration. The axially forward suction side 23 of impeller 20 is partially covered by a cover ring 28, which is rotatably connected to the impeller blades 26. At the axially forward suction side 23, the cover ring 28 has a cylindrical protrusion 27 defining an axial central inlet for liquid coolant. The rotating impeller blades 26 draw liquid coolant from the axially forward suction side 23 of the pump through the cylindrical protrusion 27 within the cover ring 28. Due to centrifugal force, the impeller blades 26 radially accelerate the liquid coolant outward. The liquid coolant is discharged through a radial discharge ring opening 24 defined by the cover ring 28 and impeller body 22 into an outlet volute 29, which circumferentially surrounds the impeller 20.

[0033] The axially sliding control sleeve body 45 is provided with two support ring grooves 46, 46' for radial support and axial fixation of the non-enclosed annular guide device body 61. The two guide devices 60, 60' guide the control sleeve 40 within the static guide cylinder 70 and fluidly separate the first hydraulic control chamber 100 and the pump chamber 25.

[0034] The control sleeve 40 is actuated by pressurizing the first hydraulic chamber 100 with pressurized coolant entering through the inlet 102 in the axial end face 75 of the static guide cylinder 70, thereby applying hydraulic pressure at the axial end face 101 of the control sleeve 40. The applied high hydraulic pressure pushes the hollow cylindrical control sleeve body 45 past the impeller 20 in the closing direction, thereby closing the radial discharge ring opening 24 to hydraulically prevent coolant pumping.

[0035] The control sleeve 40 is internally supported by an inner static support cylinder 50, which defines a second hydraulic control chamber 105 within the control sleeve body 45. The second hydraulic chamber 105 is sealed by two sealing rings 58 and 59. One sealing ring 58 is disposed in a corresponding groove 53 on the outer cylindrical surface 52 of the inner support cylinder 50. The second sealing ring 59 is disposed in a corresponding groove 54 on the inner cylindrical surface 49 of the control sleeve body 45. To actuate the control sleeve 40, the second hydraulic control chamber 105 can be pressurized by coolant entering through an inlet 56 connected to an eccentrically oriented, axially aligned hole 55 within the support cylinder 50, to provide opposing hydraulic pressure at a second axial end face 106 of the control sleeve body 45. This opposing hydraulic pressure pushes the control sleeve 40 in opposite opening directions to open the radial discharge ring opening 24 of the impeller 20.

[0036] Hydraulic pressure for actuating the control sleeve 40 is supplied by a side-channel pump 90, defined by the rear side of the impeller 20 and the opposing axial end faces 51 of the internal support cylinder 50. Pressurized coolant flows through an annular channel 95 between the internal static support cylinder 50 and the rotating rotor shaft 32 to two parallel, fluidly connected electromagnetic pressure control valves 80, 85. Control valves 80, 85 regulate the hydraulic pressure within each hydraulic control chamber 100, 105 to adapt the axial position of the control sleeve 40 to the cooling performance requirements of the cooling system. A first pressure control valve 80 fluidly connects the inlet 102 of the first hydraulic control chamber 100 to the annular channel 95, which is supplied with pressurized coolant from the side-channel pump 90. A second pressure control valve 85 fluidly connects the inlet 56 of the second hydraulic control chamber 105 to the annular channel through a hole 55 in the support cylinder 50.

[0037] Figure 2 A schematic perspective view of a control sleeve 40 is shown, which has a hollow cylindrical control sleeve body 45 and two guides 60 and 60' defined by a non-enclosed annular guide body 61. The guide body 61 is made of a plastic material, such as "iglidur H370". Each guide body 61 is arranged within a corresponding support groove 46, 46' on the outer cylindrical surface 42 of the aluminum control sleeve body 45 to radially support the guide body 61 and axially fix the guide body 61 to prevent axial displacement. The two guides 60, 60' are arranged such that the axial distance d is approximately 150% of the axial length e of the guide body 61.

[0038] The guide body 61 is provided with a labyrinthine compensating slit 65, comprising two axially oriented slit portions 65, 66 and a circumferentially oriented slit portion 68. Each axially oriented slit portion 65, 66 extends axially from one of the two axial end faces of the guide body 61. The circumferentially oriented slit portion 68 connects the two axially oriented slit portions 65, 66, such that the guide body 61 is not completely mechanically closed. The slit width of the axially oriented slit portions 65, 66 is greater than the width of the circumferentially oriented slit portion 68. The axially oriented slit portions 65, 66 allow for adaptation of the circumferential dimensions of the guide body 61 to compensate for geometric changes caused by imprecise manufacturing and thermal expansion between the control sleeve 40 and the static guide cylinder 70. The circumferentially oriented slit portion 68 is very small or can be substantially zero to avoid associated leakage on the guides 60, 60'. As a result, the mechanically unclosed and therefore adaptable guide body 61 is hydraulically closed.

Claims

1. A variable mechanical automotive coolant pump (10), comprising: A rotatable impeller (20) is rotatably connected to a rotatable rotor shaft (30), the impeller including a discharge radial outer side; A non-rotatable control sleeve (40) having a hollow cylindrical control sleeve body (45), the non-rotatable control sleeve having a radially outer side and being configured to be axially slidably guided within a static guide cylinder (70), for regulating the flow rate of the variable mechanical automotive coolant pump (10) by closing or opening the discharge radially outer side (21) of the impeller (20), and At least one separate guide device (60) guides the radially outer side (42) of the control sleeve (40) within the static guide cylinder (70). Each of at least one of the individual guiding devices is in direct contact with the static guiding cylinder. The control sleeve (40) is guided by two independent guide devices (60, 60'), the guide device body extending radially beyond the outer cylindrical surface of the control sleeve by at least 20% of the radial thickness of the guide device body, such that the guide device is not completely embedded in the control sleeve, thereby preventing the control sleeve from contacting the static guide cylinder.

2. The variable mechanical automotive coolant pump (10) according to claim 1, wherein the axial position of the control sleeve (40) is continuously adaptable, such that the cross-sectional area of ​​the opening of the outer radial side (21) of the impeller (20) is completely variable.

3. The variable mechanical automotive coolant pump (10) according to claim 1 further includes a hydraulic actuation system having a hydraulic control chamber (100, 105) for actuating the control sleeve (40).

4. The variable mechanical automotive coolant pump (10) according to claim 1, wherein the guide device (60) is defined by a non-closed annular guide device body (61) having a compensation slit (65).

5. The variable mechanical automotive coolant pump (10) according to claim 1, wherein the axial length (e) of the guide device (60) is less than 25% of the axial length (F) of the control sleeve (40).

6. The variable mechanical automotive coolant pump (10) according to any one of claims 3-5, wherein the guide body (61) is provided with a labyrinth-type compensating slit (65).

7. The variable mechanical automotive coolant pump (10) according to any one of claims 1-5, wherein the guide device (60) is embedded in the control sleeve body (45).

8. The variable mechanical automotive coolant pump (10) according to any one of claims 1-5, wherein the guide device (60) is made of plastic material.

9. The variable mechanical automotive coolant pump (10) according to any one of claims 1-5, wherein the slidable control sleeve (40) is made of an aluminum-based material.

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