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Title:
SWITCHABLE MECHANICAL COOLANT PUMP
Document Type and Number:
WIPO Patent Application WO/2019/105531
Kind Code:
A1
Abstract:
A switchable mechanical coolant pump (100,200) with an input rotor unit (110,210) comprising a input rotor shaft (122,222) and comprising a pulley wheel (108,208) co-rotatably fixed to the input rotor shaft (122,222), an output rotor unit (114,214) comprising a pump wheel (124,224), an electromagnetically actuated wet friction clutch (116,216) comprising a first friction disc (126,226) co-rotatably fixed to the pump wheel (124,224), a second friction disc (128,228) comprising a ferromagnetic means (128,228), the second friction disc (128,228) being co-rotatably fixed to the input rotor shaft (122,222) and being axially shiftable with respect to the first friction disc (126,226), and a static electromagnetic coil (130,230), the wet friction clutch (116,216) selectively coupling the input rotor unit (110,210) with the output rotor unit (114,214), a cylindrical control slider ring (118,218) which is slidable in axial direction with respect to the pump wheel (124,224) between an open and a closed position thereby selectively surrounding the pump wheel (124,224), and an auxiliary hydraulic system (120,220) with an auxiliary hydraulic pump (144,244) pressurizing the auxiliary hydraulic system (120,220) and being mechanically driven by the Input rotor unit (110,210), the auxiliary hydraulic system (120,220) hydraulically actuating the control slider ring (118,218).

Inventors:
FOURNIER, Arnaud (16 rue Henri Dunant, Yutz, 57970, FR)
BERTRAND, Elie (5 place de la République, Thionville, 57100, FR)
FINIDORI, Laurent (118 Grand'rue, Bertrange, 57310, FR)
RYBICKI, Gilles (11 bis rue de la libération, Metz, 57000, FR)
SIMON, Gilles (26 la sapinière, Montois la Montagne, 57860, FR)
RANDOULET, Florent (3 rue du capitole, Lerouville, 55200, FR)
LEFERT, Maxime (19 Rue des Saules, Beaumont en Véron, 37420, FR)
Application Number:
EP2017/080687
Publication Date:
June 06, 2019
Filing Date:
November 28, 2017
Export Citation:
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Assignee:
PIERBURG PUMP TECHNOLOGY GMBH (Alfred-Pierburg-Straße 1, Neuss, 41460, DE)
International Classes:
F01P7/16; F04D13/02; F04D15/00
Domestic Patent References:
WO2013079103A12013-06-06
WO2009143832A22009-12-03
Foreign References:
DE102015216141A12016-03-03
DE102014009367B32015-03-05
DE102008015707A12008-10-02
DE102011012826B32012-01-12
DE102011076719A12012-12-06
Attorney, Agent or Firm:
PATENTANWÄLTE TER SMITTEN EBERLEIN-VAN HOOF RÜTTEN PARTNERSCHAFTSGESELLSCHAFT MBB (Burgunderstr. 29, Düsseldorf, 40549, DE)
Download PDF:
Claims:
C L A I M S

1. A switchable mechanical coolant pump (100,200) with

an input rotor unit (110,210) comprising a input rotor shaft (122,222) and comprising a pulley wheel (108,208) co- rotatably fixed to the Input rotor shaft (122,222), and

an output rotor unit (114,214) comprising a pump wheel (124,224), an electromagneticaily actuated wet friction clutch (116,216) comprising

a first friction disc (126,226) co-rotatably fixed to the pump wheel (124,224),

a second friction disc (128,228) comprising a ferromagnetic means (128,228), the second friction disc (128,228) being co- rotatably fixed to the input rotor shaft (122,222) and being axially shiftable with respect to the first friction disc

(126,226), and

a static electromagnetic coil (130,230),

the wet friction clutch (116,216) selectively coupling the input rotor unit (110,210) with the output rotor unit (114,214),

a cylindrical control slider ring (118,218) which is slidable in axial direction with respect to the pump wheel (124,224) between an open and a closed position thereby selectively surrounding the pump wheel (124,224), and

an auxiliary hydraulic system (120,220) with an auxiliary hydraulic pump (144,244) being mechanically driven by the input rotor unit (110,210) and pressurizing the auxiliary hydraulic system (120,220), the auxiliary hydraulic system (120,220) hydraulically actuating the control slider ring (118,218). 2. The switchable mechanical coolant pump (100,200) of claim 1, wherein the hydraulic actuation of the control slider ring (118,218) is operatively connected with the electromagnetic actuation of the pump wet friction clutch (116,216).

3. The switchable mechanical coolant pump (100,200) of any preceding claim, wherein the auxiliary hydraulic pump (144,244) is a volumetric pump and wherein the auxiliary hydraulic system (120,220) Is provided with a hydraulic balance port (154,254) connecting the auxiliary hydraulic system (120,220) with a !ow pressure.

4. The switchable mechanical coolant pump (100,200) of any preceding claim, wherein the auxiliary hydraulic pump (144,244) is provided as a radial piston pump and wherein the input rotor shaft (122,222) is provided with a cam structure (150,250) for driving the radial piston pump (144,244).

5. The switchable mechanical coolant pump (100,200) of any preceding claim, wherein the control slider ring (118,218) is preloaded in the axial direction facing away from the pump wheel (124,224) by a preload spring (138,238) so that the control slider ring (118,218) is preloaded into the open position.

6. The switchable mechanical coolant pump (100,200) of any preceding claim, wherein the auxiliary hydraulic system (120,220) is continuously pressurized by the auxiliary hydraulic pump (144,244), and wherein the auxiliary hydraulic system (120,220) Is provided with a switchable hydraulic control valve (152,252) controlling the auxiliary hydraulic system (120,220) pressure and being operatively connected with the pump wet clutch (116,216).

7. The switchable mechanical coolant pump (100) of claim 7, wherein the hydraulic control valve (152) is provided as a solenoid valve which is electrically coupled with the wet clutch electromagnetic coil (130).

8. The switchable mechanical coolant pump (200) of claim 7, wherein the first friction disc (226) is provided axially shiftable and comprises a second ferromagnetic means (226), and wherein the hydraulic control valve (252) comprises an auxiliary hydraulic system outlet port (258) and comprises an outlet control means (260) co-movably fixed to the axially shiftable friction disc (226) and selectively closing the auxiliary hydraulic system outlet port (258).

Description:
Switchable mechanical coolant pump The Invention is directed to a switchable mechanical coolant pump, in particular for providing a liquid coolant for an automotive engine.

A mechanical automotive coolant pump is mechanically driven by an automotive internal combustion engine so that the coolant pump generally rotates with a rotational speed which is proportional to the rotational speed of the engine. In some situations, and in particular after starting a cold engine, no coolant flow Is needed. The coolant output can be adapted to the cooling requirement of the engine with a switchable mechanical coolant pump.

WO 2013/079103 A1 discloses a switchable mechanical coolant pump being provided with an electromagnetica!ly actuated wet friction clutch so that the rotational connection between the pulley wheel of the pump and the pump wheel can be selectively engaged or disengaged as needed. However, the friction discs which are co-rotatably fixed to the driven pulley wheel still rotate within the coolant in the disengaged clutch state thereby generating a hydrodynamic drag moment acting on the pump wheel. As a result, the pump provides a considerable coolant output even if no coolant output is needed.

WO 2009/143832 A2 discloses a switchable mechanical coolant pump being provided with a cylindrical control slider ring which is axially shiftable with respect to the pump wheel. The cylindrical control slider ring can be selectively shifted over the pump wheel to interrupt the coolant output. However, energy Is consumed for driving the pump wheel even if no coolant output is needed so that the pump efficiency is reduced. It is an object of the invention to provide a switchable mechanical coolant pump which allows efficiently Interrupting the pump coolant discharge.

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

The switchable mechanical coolant pump according to the invention is provided with an Input rotor unit which comprises an input rotor shaft and a pulley wheel which are rotatable about a common axis of rotation. The pulley wheel is co-rotatably fixed to the Input rotor shaft and is suitable to be mechanically driven, for example, by an internal combustion engine. Generally, the pulley wheel and, as a result, the input rotor shaft can be driven by any kind of mechanical transfer means, for example by a transmission belt, a gear wheel, a friction wheel, etc. Preferably, the pulley wheel is driven by the engine via a transmission belt.

The switchable mechanical coolant pump according to the invention is also provided with an output rotor unit comprising a rotatable pump wheel. The pump wheel is provided rotatably and can rotate independently of the rotating input rotor shaft. Preferably, the pump wheel, the input rotor shaft and the pulley wheel are provided rotatable about a common axis of rotation.

The switchable mechanical coolant pump according to the invention is also provided with an electromagnetically actuated wet friction clutch. The wet friction clutch comprises a first friction disc which is provided co-rotatably fixed to the pump wheel. The wet friction clutch also comprises a second friction disc which is co-rotatably fixed to the input rotor shaft and is driven by the engine via the pulley wheel. The second friction disc is axially shiftable with respect to the first friction disc and comprises a ferromagnetic means. Both friction discs are located in a wet zone of the pump, the wet zone being provided with the coolant. In the engaged clutch state, both friction discs are in full frictional contact with each other so that both friction discs rotate with a common rotational speed. As a result, the pump wheel is co-rotatably coupled to the driven pulley wheel In the engaged clutch state.

The wet friction clutch also comprises a static electromagnetic coil being arranged in a dry zone of the pump so that the electromagnetic coil and the driving electronics of the electromagnetic coil are not in contact with the coolant. The electromagnetic coil is axially positioned at the pump- wheel-remote side of the second friction disc. If the electromagnetic coll Is electrically energized, the ferromagnetic means of the second friction disc Is attracted by the electromagnetic coil In axial direction thereby separating the second friction disc from first friction disc. As a result, the frictional contact is disengaged thereby Interrupting the co-rotational coupling of the pump wheel and the pulley wheel.

The electromagnetlcally actuated wet friction clutch allows selectively coupling/decoupling the input rotor unit with/from the output rotor unit by energizing the electromagnetic coil as needed and, as a result, allows controlling the coolant discharge of the pump, for example according to the need of the engine.

The switchable mechanical coolant pump according to the invention is also provided with a cylindrical control slider ring which is slidable In axial direction with respect to the pump wheel between an open and a closed position. In the closed position, the control slider ring radially surrounds and completely covers the pump wheel. This allows a considerable interruption of the coolant discharge of the pump independently of the rotational speed of the pump wheel.

The switchable mechanical coolant pump according to the invention is also provided with an auxiliary hydraulic system. The auxiliary hydraulic system comprises an auxiliary hydraulic pump pressurizing the auxiliary hydraulic system. The auxiliary hydraulic pump is mechanically driven . by the engine via the Input rotor unit. The auxiliary hydraulic system hydraulically actuates the control slider ring. In particular, the auxiliary hydraulic system allows pressurizing a pump wheel-remote axial end of the control slider ring thereby shifting the control slider ring in axial direction over the pump wheel. In this position, the control slider ring radially surrounds the pump wheel so that the coolant throughput is substantially blocked. The auxiliary hydraulic system allows simply controlling the control slider ring position via the pressure of the auxiliary hydraulic system, for example via a hydraulic control valve.

The combination of the electromagnetically actuated wet friction clutch and the hydraulically actuated control slider ring allows the switchable mechanical coolant pump according to the invention to interrupt the pump coolant discharge energy efficiently and providing a true zero -flow, if needed.

Preferably, the hydraulic actuation of the control slider ring Is operatively connected with the electromagnetic actuation of the pump wet friction clutch, so that the movement of the control slider ring between the open and the closed position is coupled with the engagement/disengagement of the clutch. The control slider ring is moved into the open position If the clutch is engaged, and the control slider ring is axially shifted over the pump wheel into the closed position if the clutch Is disengaged. If no coolant discharge is needed, the clutch is disengaged to interrupt the drive of the pump wheel and the control slider ring surrounds the pump wheel to interrupt the coolant discharge caused by the remaining pump wheel rotation.

In a preferred embodiment of the invention, the auxiliary hydraulic pump is a volumetric pump. This allows a simple implementation of the auxiliary pump, for example, by a cam-driven piston pump. The auxiliary hydraulic system is provided with a hydraulic balance port being connected to a low pressure, for example of a lubricant tank, to avoid an overpressure in the auxiliary hydraulic system and, as a result, to avoid a blocking of the moveable part of the volumetric pump. The maximum pressure of the auxiliary hydraulic system can be simply defined via the hydraulic cross section of the hydraulic balance port.

Preferably, the auxiliary hydraulic pump of the auxiliary hydraulic system is provided as a radial piston pump which is driven by a cam structure provided at the input rotor shaft of the input rotor unit. This allows a very simple, compact and reliable implementation of the auxiliary hydraulic pump. In a preferred embodiment of the invention, the control slider ring is preloaded in the axial direction facing away from the pump wheel by a preload spring so that the control slider ring is preloaded into the open position. As a result, in case of a malfunction of the hydraulic control slider ring actuation system, the control slider ring is shifted away from pump wheel into the open position so that the coolant discharge is not interrupted. This allows a failsafe operation of the coolant pump.

Preferably, the auxiliary hydraulic system is continuously pressurized by the auxiliary hydraulic pump so that no complex control mechanism for the auxiliary hydraulic pump is needed. The auxiliary hydraulic system Is provided with a hydraulic control valve to allow controlling the auxiliary hydraulic system pressure and, as a result, to allow controlling the control slider ring movement. The hydraulic control valve is in operative connection with the electromagnetic wet clutch actuation system so that the control slider ring movement and the engagement/disengagement of the pump clutch can be coordinated. This allows a very efficient control of the pump coolant discharge. In a preferred embodiment of the invention, the hydraulic control valve is provided as a solenoid valve which is electrically coupled with the wet dutch electromagnetic coil. This allows a cost-efficient Implementation of the hydraulic control valve and a simple electric coupling of the hydraulic control slider ring actuation system and the electromagnetic clutch actuation system.

Alternatively, the hydraulic control valve comprises an auxiliary hydraulic system outlet port and an outlet control means. The outlet control means is co-movably attached to the axially shiftable friction disc and selectively doses the auxiliary hydraulic system outlet. The outlet control means can be, for example, simply provided as an axial surface of the friction disc. If the friction disc is axially moved during the friction clutch disengagement, the outlet control means being co-movably attached to the friction disc closes the auxiliary hydraulic system outlet port. As a result, the auxiliary hydraulic system pressure increases so that the control slider ring is moved into the closed position. The control slider ring actuation is therefore mechanically coupled to the axial friction disc position and, as a result, coupled to the engagement/disengagement of the pump clutch. This allows a simple and reliable mechanical coupling of the control slider ring movement and the pump clutch state and does not require any additional electric control means for the control slider ring actuation. Two embodiments of the invention are described with reference to the accompanying drawings, wherein

figure 1 shows a schematic longitudinal section of a first embodiment of a switchable mechanical coolant pump according to the invention, and

figure 2 shows a schematic longitudinal section of a second embodiment of a switchable mechanical coolant pump according to the invention. Figure 1 shows a swltchable mechanical coolant pump 100 for providing a liquid coolant for an internal combustion engine 102, The coolant pump 100 Is mechanically driven by a rotating means 104 of the engine 102 via a transmission belt 106, The transmission belt 106 drives a pulley wheel 108 of a pump Input rotor unit 110.

The coolant pump 100 comprises a static pump frame 112, the Input rotor unit 110, an output rotor unit 114, an electromagnetical!y actuated wet friction clutch 116, a cylindrical control slider ring 118 and an auxiliary hydraulic system 120.

The input rotor unit 110 comprises the mechanically driven pulley wheel 108 and a rotatable input rotor shaft 122 being rotatably supported within and at the static pump frame 112 by an input rotor shaft bearing 123, The pulley wheel 108 is co- rotatably attached to the rotatable Input rotor shaft 122.

The output rotor unit 114 comprises a rotatable pump wheel 124 being rotatable with respect to the input rotor shaft 122. The pump wheel 124, the input rotor shaft 122 and the pulley wheel 108 are provided rotatable about a common axis of rotation Al.

The elect romagnetically actuated wet friction clutch 116 comprises two friction discs 126,128. The first friction disc 126 is co-rota tably attached to an axial backside of the pump wheel 124. The backside faces the second friction disc 128. The second ferromagnetic friction disc 128 is co-rotatably fixed to the input rotor shaft 122 and Is axially shiftable with respect to the first friction disc 126. The second friction disc 128 Is axially preloaded towards the first friction disc 126 by a friction disc preload spring 132. As a result, the friction discs 126,128 are in frictional contact as long as no other axial force is effective with respect to the second friction disc 128. In the shown engaged clutch state, the friction discs 116,118 rotate with the same rotational speed so that the pump wheel 124 and the driven pulley wheel 108 are co-rotatably coupled.

The electromagnetically actuated wet friction clutch 116 is provided with a static electromagnetic coll 130 being supported within the static pump frame 112 by a static coil body 134. The electromagnetic coil 130 is electrically energized by an engine control unit 136 to disengage the wet friction dutch 116 and, as a result, to interrupt the drive of the pump wheel 124 as needed.

If the electromagnetic coil 130 Is energized by the engine control unit 136, the ferromagnetic second friction disc 128 Is axially attracted by the electromagnetic coil 130 so that the second friction disc 128 Is axially moved against the friction disc preload spring 132 and away from the first friction disc 126. As a result, the frictional contact between the friction discs 126,128 is interrupted so that the pump wheel 124 is not driven by the engine 102 via a direct friction contact anymore.

The cylindrical control slider ring 118 is positioned within the static pump frame 112 so that the cylinder axis Cl of the cylindrical control slider ring 118 corresponds with the axis of rotation Al. The cylindrical control slider ring Is provided with an inner radius being larger than the outer radius of the pump wheel 124. The control slider ring 118 is slidable in axial direction with respect to the pump wheel 124 between an open and a closed position. The control slider ring 118 completely surrounds the pump wheel 124 in the closed position thereby blocking the coolant discharge of the coolant pump 100 independently of the rotational speed of the pump wheel 124. The control slider ring 118 does not surround the pump wheel 124 in the open position and, as a result, does not affect the coolant discharge of the coolant pump 100 in the open position. The control slider ring 118 allows selectively interrupting the coolant discharge of the coolant pump 100 as needed. The control slider ring 118 is axially preloaded into the open position by a control slider ring preload spring 138, As a result, the coolant discharge of the coolant pump 100 is not interrupted if no additional axial force is effective with respect to the slidable control slider ring 118. This allows a failsafe operation of the coolant pump 100.

The control slider ring 118 Is hydraulically actuated by the auxiliary hydraulic system 120, in particular by the hydraulic pressure of a control chamber 140 of the auxiliary hydraulic system 120. The control chamber 140 is partially defined in axial direction by an axial control slider ring end 142. As a result, the control chamber 140 pressure pushes the control slider ring 118 in axial direction against the preload spring 138 into the closed position.

The control chamber 140 is pressurized with the coolant by an auxiliary radial piston pump 144 being hydraulically connected to an inlet chamber 146. The inlet chamber 146 is provided with coolant of atmospheric pressure via an axial hydraulic channel 148 being located in the center of the input rotor shaft 122. The auxiliary radial piston pump 144 is mechanically driven by a cam structure 150 being provided at and radially protruding from the input rotor shaft 122. As a result, the control chamber 140 is continuously pressurized as long as the engine 102 drives the pulley wheel 108.

The auxiliary hydraulic system 120 is provided with a solenoid control valve 152. The control valve 152 hydraulically connects the pressurized control chamber 140 with the inlet chamber 146 of atmospheric pressure via a hydraulic balance port 154. The control valve 152 can change the coolant throughput of the hydraulic balance port 154 between a minimum- throughput and a maximum-throughput. The control valve 152 always permits a minimum balance port throughput to avoid an overpressure in the control chamber 140 and, In particular, to avoid a blocking of the piston pump 144,

In the minimum-throughput state of the control valve 152, the control chamber 140 Is loaded with a high pressure so that the control slider ring 118 is pushed into the closed position. In this position, the control slider ring 118 surrounds the pump wheel 124 and thereby interrupts the coolant discharge of the coolant pump 100. In the maximum-throughput state of the control valve 152, the control chamber 140 Is provided with atmospheric pressure via the balance port 154. As a result, the control slider ring 118 is pushed into the open position by the control slider ring preload spring 138. The control valve 152 state Is electrically controlled by the engine control unit 136 which also electrically controls the electromagnetic wet clutch

116. This allows the engine control unit 136 to simply co-actuate the control slider ring 118 and the wet clutch 116. If no coolant discharge of the coolant pump 100 is needed, the engine control unit 136 energizes the electromagnetic coil 130 to disengage the wet clutch 116 and thereby stop the drive of the pump wheel 124. However, the rotation of the second friction 128 disc in direct proximity of the pump wheel 124 can cause a hydrodynamic drag moment hydraulically driving the pump wheel 124 and thereby providing a considerable coolant discharge.

To block the remaining coolant discharge of the coolant pump 100, the engine control unit 136 can simultaneously switch the control valve 152 to the minimum-throughput state so that the control slider ring 118 is moved into the closed position, in which the control slider ring 118 completely surrounds the pump wheel 124. The co-actuation of the wet clutch 116 and of the control slider ring 118 allows to very efficiently interrupt the pump coolant discharge as needed.

Figure 2 shows an alternative swltchable mechanical coolant pump 200 according to the Invention. The features of the coolant pump 200 of figure 2 which correspond with the features of the coolant pump 100 of figure 1 have a reference number increased by 100.

The auxiliary hydraulic system 220 of the coolant pump 200 is provided with a hydraulic balance port 254 connecting the auxiliary hydraulic system control chamber 240 with the low pressure of a hydraulic clutch chamber 256. The hydraulic balance port 254 comprises an axial opening 258 axially facing an axial surface 260 of the first friction disc 226. The electromagnetically actuated wet friction clutch 216 of the coolant pump 200 comprises two ferromagnetic friction discs 226,228. The first friction disc 226 is co-rotatably and co-movably attached to the axial backside of the pump wheel 224 which faces the second friction disc 228. The second friction disc 228 is co-rotatably fixed to the input rotor shaft 222. Both friction discs 226,228 are axially shiftable with respect to the electromagnetic coil 230.

The electromagnetic coil 230 is energized by the engine control unit 236 either with a low-level electric energy or with a high-level electric energy, or is not energized at all. If the electromagnetic coil 230 is not energized, the second friction disc 228 is axially preloaded towards the first friction disc 226 by the friction disc preload spring 232. As a result, the friction discs 226,228 are in frictional contact thereby co-rotatably coupling the pump wheel 224 with the driven pulley wheel 208.

If the electromagnetic coil 230 is energized with the iow-levei electric energy, only the second friction disc 228 is axially attracted by the electromagnetic coil 230 so that the second friction disc 228 is axially moved against the preload spring 232 and away from the first friction disc 226, As a result, the frictional contact between the friction discs 226,228 is opened thereby Interrupting the co-rotatable coupling between the pump wheel 224 and the pulley wheel 208 so that the pump wheel 224 is not driven by the engine 202 via a direct friction contact anymore

If the electromagnetic coil 230 is energized with the high-level electric energy, the first friction disc 226 Is also axially attracted by the electromagnetic coil 230, As a result, the first friction disc 226 Is axially moved towards the electromagnetic coil 230 so that the axial friction disc surface 260 covers the axial hydraulic balance port opening 258. The axial friction disc surface 260 together with the axial hydraulic balance port opening 258 provide a hydraulic control valve 252 controlling the throughput of the hydraulic balance port 254.

If the axial friction disc surface 260 covers the axial hydraulic balance port opening 258, the hydraulic balance port 254 throughput is considerably reduced so that the auxiliary hydraulic system control chamber 240 is loaded with a high pressure by the auxiliary radial piston pump 244. The high control chamber pressure axially loads the axial control slider ring end 142 so that the control slider ring 218 Is axially pushed into the closed position. The balance channel throughput is not entirely interrupted to avoid an overpressure of the auxiliary system 220 and, in particular, of the control chamber 240.

The clutch 216 state and the control slider ring 218 position both are controlled by the engine control unit 236 energizing the electromagnetic coil. The operative coupling of the friction clutch 216 actuation and of the control slider ring 218 actuation allows providing three pump states with different coolant discharge pressures. The pump state can be simply controlled via the electric energy supplied to the electromagnetic coil 230. If the electromagnetic coil 230 is not energized, the wet friction clutch 216 is engaged and the control slider ring 218 is in the open position. As a result, the pump wheel 224 is driven by the engine 202 and the coolant pump 200 provides the maximum coolant discharge pressure.

If the electromagnetic coll 230 is energized with the low-level electric energy, the wet friction clutch 216 gets disengaged while the control slider ring 218 remains In the open position. The second friction disc 228 rotating within the hydraulic clutch chamber 256 generates a hydrodynamic drag moment effective with respect to the pump wheel 224. As a result, the pump wheel 224 rotates with a reduced rotational speed so that the coolant pump 200 provides a reduced coolant discharge pressure.

If the electromagnetic coll 230 Is energized with the high-level electric energy, the wet friction clutch 216 remains disengaged while the control slider ring 218 is moved into the closed position. As a result, the control slider ring 218 covers the pump wheel 224 so that the coolant discharge of the coolant pump 200 is efficiently interrupted.

Reference list

100 switchable mechanical coolant pump

102 internal combustion engine

104 rotating means

106 transmission belt

108 pulley wheel

110 input rotor unit

112 static pump frame

114 output rotor unit

116 electromag netica!ly actuated wet friction clutch 118 cylindrical control slider ring

120 auxiliary hydraulic system

122 rotatable input rotor shaft

123 input rotor shaft bearing

124 pump wheel

126 first friction disc

128 second friction disc

130 electromagnetic coil

132 friction disc preload spring

134 coil body

136 engine control unit

138 control slider ring preload spring

140 auxiliary hydraulic system control chamber 142 axial control slider ring end

144 auxiliary radial piston pump

146 auxiliary hydraulic system inlet chamber 148 axial hydraulic channel

150 cam structure

152 solenoid control valve

154 hydraulic balance port

200 switchable mechanical coolant pump 202 internal combustion engine

204 rotating means

206 transmission belt

208 pulley wheel

210 input rotor unit

212 static pump frame

214 output rotor unit

216 electromagnetically actuated wet friction dutch 218 cylindrical control slider ring

220 auxiliary hydraulic system

222 rotatable input rotor shaft

223 input rotor shaft bearing

224 pump wheel

226 first friction disc

228 second friction disc

230 electromagnetic coil

232 friction disc preload spring

234 coil body

236 engine control unit

238 control slider ring preload spring

240 auxiliary hydraulic system control chamber 242 axial control slider ring end

244 auxiliary radial piston pump

246 auxiliary hydraulic system inlet chamber

248 axial hydraulic channel

250 cam structure

252 hydraulic control valve

254 hydraulic balance port

256 hydraulic clutch chamber

258 axial hydraulic balance port opening

260 axial first friction disc surface

A1,A2 axes of rotation

C1,C2 cylinder axes