Electrically drivable valve for controlling volumetric flows in a heating and/or cooling system of a motor vehicle

An electrically drivable valve for controlling volumetric flows in a heating and/or cooling system of a motor vehicle, including a housing, from which at least two channels, preferable an inlet channel and an outlet channel, branch off, wherein a disk-shaped valve body is arranged in the housing, which valve body can be rotated about an axis of a drive shaft and has a control contour. For a valve that is simple to produce in regard to the design of the valve, the single control contour of the valve body controls a bypass circuit and a cooler circuit of the heating and/or cooling system.

BACKGROUND OF THE INVENTION

Field of the Invention

The invention relates to an electrically drivable valve for controlling volumetric flows in a heating and/or cooling system of a motor vehicle.

Description of the Background Art

Thermal management in cooling systems of motor vehicles is carried out today to reduce consumption, to reduce CO2emissions, and to increase comfort. Depending on the thermal requirements, the coolant stoppage is realized in this case during warm-up, the coolant temperature of the internal combustion engine is controlled according to load conditions, and one or more auxiliary circuits such as the transmission fluid, engine oil, or heating circuit are controlled or switched. Motor vehicle cooling systems in this case are formed of an internal combustion engine, a cooling element, a pump, and a control valve.

A valve which is electrically driven by a DC motor and has a disc-shaped valve body is known from U.S. Pat. No. 5,950,576 A. In this case, the coolant is conducted from one side into the interior of the valve and through the valve body, redirected by 180° and again conducted through the valve body, and taken out on the same side of the valve. High pressure losses arise here because of the redirection. It is especially disadvantageous that the valve body in this design has three openings for two inlet ports and one outlet port; this results in a high sealing cost.

A valve with disc-shaped valve body is also disclosed in DE 10 2006 053 310 A1. The valve has a housing with at least one inlet channel and at least one outlet channel, whereby the disc-shaped valve body is mounted rotatably about the axis of a shaft. Moreover, the valve body has rotation angle-dependent opening characteristics for controlling volumetric flows, whereby a plurality of discrete openings are provided to connect an individual inlet channel to the one outlet channel. When the valve body moves, this has the result that the edges of the plurality of openings slide constantly over the seals and this thus causes greater wear on the seal. The inflow and outflow of the coolant occur axially to the rotation axis in the opposite direction.

It is disadvantageous for electrically driven valves that extensive sealing material is necessary for sealing the plurality the openings, as a result of which the valve is structurally complicated and very cost-intensive. At the same time, the heavy wear of the seals shortens the lifetime of the valve.

SUMMARY OF THE INVENTION

It is therefore an object of the invention to provide an electrically drivable valve which has a structurally simple design and a long lifetime.

In an exemplary embodiment, the only one control contour of the valve body controls a bypass circuit and a radiator circuit of the heating and/or cooling system. This has the advantage that the sealing expenses decline when only one control contour of the valve body is used. At the same time, seal wear is reduced, as a result of which the valve's lifetime is increased. The only one control contour in this case forms only one passage for the coolant on the valve body. Such a valve can be used both as an ingress regulator and egress regulator for the coolant of an internal combustion engine.

The control contour can be formed as an opening of the valve body which is shaped like a full circle. In the case of disc-shaped valve bodies, the construction expenses decline during the production of the valve, which reduces the cost.

The control contour can be formed by an outer shape of a circle-segment-like, full-surface valve body. In this case, a passage for the volumetric flow is created by the outer shape of the disc-shaped valve body, said shape which does not have the shape of a full circle; the passage allows a corresponding control depending on the valve body position.

In an embodiment, the control contour can be formed as a baffle on a lateral surface of the valve body. Such a baffle, extending approximately parallel to the housing, thereby advantageously has the function of controlling an additional coolant circuit. A heating circuit can already be released by means of this simple-to-produce baffle, for example, during the warm-up when the bypass and radiator circuits are still closed to increase the corresponding comfort in the passenger compartment, e.g., during winter operation.

In an embodiment, the valve body can be formed pivotable relative to the axis. In addition to the rotation of the valve body about the axis, the pivoting of the valve body relative to the rotation axis represents an additional degree of freedom in the movement of the disc-like valve body. This makes it possible to operate the valve body drive, formed as an electric motor, with a smaller force. The valve body mounted rotatably on the axis in this case easily changes its rotation angle variably depending on the instructions of a control device.

In an embodiment, the valve body can be formed of metal or of a coolant-resistant plastic, whereby the plastic preferably can contain glass fibers and/or additives that optimize sliding. The additives constitute a percentage between 10% and 70%. The use of additives that optimize sliding enables easy movement of the valve body in view of the reduced friction.

In an embodiment, the valve body on its surface can be provided with a seal for sealing against the housing. It is assured by means of such a seal that the volumetric flow to be controlled is influenced only by the control contour itself and that no leaks arise on the valve body.

The seal can be disposed in the housing to seal the valve body. The seals in this case can be formed particularly as molded seals and form a positive fit for sufficient sealing.

In an embodiment, the valve body, disposed on a shaft, together with the shaft or only the valve body, can be under a preload by means of at least one resilient element relative to an opening of at least one connecting piece. Due to this preload, it is possible that the valve body executes an adjusting movement in the case of a wearing seal in order not to exceed a leakage specified over the valve's lifetime.

In an embodiment, an expanding wax thermostat can be disposed in the housing as valve failure protection. The expanding wax thermostat assures sufficient cooling of the internal combustion engine when a critical coolant temperature is reached. Thermal damage in the heating and/or cooling system can be prevented as a result. The position of the expanding wax thermostat in the housing is the same when the valve is used either as an ingress or egress regulator.

According to an embodiment, the housing can have connections for the tubes of a separate expanding wax thermostat. Thus, the thermostat can also be disposed outside the valve, as a result of which it is easier to replace when necessary.

According to an embodiment, a housing wall of the actuator, by which the valve can be electrically drivable, can be at the same time a wall of the valve housing. Installation space can be saved as a result.

According to an embodiment, a position reset of the valve body can occur via, for example, a Hall sensor or a Hall switch.

According to embodiment, the reference points of the Hall switch can be formed via one or more mechanically formed end positions or via magnets.

DETAILED DESCRIPTION

FIG. 1shows a cooling circuit1of a motor vehicle with valve2of the invention as an ingress regulator. Cooling circuit1in this case has an internal combustion engine3whose engine outlet4is connected to a cooling element5. Radiator return6is connected to valve2. The outlet of valve2leads to intake side22of a pump7, which in turn is connected to an internal combustion engine3. A bypass or bypass circuit9, which connects engine outlet4directly to valve2and thus again to pump7and internal combustion engine3, is provided between engine outlet4and radiator inflow8. Cooling element5is cooled by air (arrow P). A fan10is located behind cooling element5.

FIG. 2differs fromFIG. 1only in that valve2functions as an egress regulator and is therefore connected between engine outlet4and radiator inflow8. At the same time, valve2controls bypass circuit9, which connects engine outlet4to intake side22of pump7.

In the case of valve2formed as an ingress regulator, simply stated the valve outlet goes to intake side22of pump7, and bypass circuit9and radiator return6form the valve inlets. In a valve2used as an egress regulator, engine outlet4forms the valve inlet, whereas bypass circuit9and radiator inflow8form the two valve outlets.

Valve2functioning as an ingress regulator is shown inFIG. 3. Valve2in this case comprises a housing11, which has three connecting pieces12,13,14. Connecting piece12here connects valve2to pump7and thus represents an outlet channel. Second connecting piece13connects valve2to bypass circuit9, whereas third connecting piece14connects valve2to radiator return6. Connecting pieces13and14in this case therefore represent inlet channels.

Valve body15, as illustrated inFIGS. 4aand 4b, is formed as a full-circle-shaped, disc-shaped body, which has a decentered opening17as a control contour. A control contour in this case forms the only passage for the coolant within ingress or egress regulator2,3. The bypass circuit and the radiator circuit can be controlled by means of this one flat disc and the one opening17, depending on whether valve2is used as the ingress regulator or as the egress regulator. If it were to be necessary that a plurality of coolant circuits are to be controlled, additional openings must be formed on disc-shaped valve support15in accordance with the number of the additional coolant circuits.

As is evident fromFIG. 5, it is not absolutely necessary that an opening in valve body15must be designed absolutely as a control contour for controlling the volumetric flow of the coolant. Alternatively,FIG. 5ashows a control contour, which is formed as a baffle18on lateral side19of valve body15. An additional coolant circuit can be controlled by means of said baffle18. Thus, for example, during the warm-up of internal combustion engine3with a still closed bypass circuit or radiator circuit, a heating circuit can be released in this way in order to increase, e.g., the passenger comfort during winter operation. Baffle18, however, also enables an uncontrolled inflow/outflow from additional coolant circuits into valve2.

FIG. 5bshows a valve body20formed like a circle segment. Only the desired channel is closed by means of this circle-segment-like valve body20, whereas opening17in the embodiment of valve body15according toFIG. 5areleases the desired ingress or egress connecting piece12,13,14. In both cases, the flow entering through valve2runs approximately parallel to the rotation axis of valve body15,20and thereby always in one direction.

Valve body15or20is made of a metal or of an injection-moldable plastic. In the case of the version made of plastic, it preferably contains glass fibers with a percentage between 10% and 70% and is resistant to the coolant. In addition, additives, optimizing sliding, such as PTFE (polytetrafluoroethylene) can be used in the plastic. Said sliding-optimizing additives reduce the friction of valve body15,20on housing11. Valve body15,20in this case should have on its outer surface a flatness of less than +/−0.5 mm.

In addition, there are the options that the disc-shaped valve body15,20has one or more recesses or that it is coated with a sealing material on its outer surface and/or lateral surface19. Valve body15,20can have raised areas on its surface or valve body15,20can have non-penetrating recesses.

Valve body15,20and shaft16can be a part that is made of plastic. Alternatively, valve body15,20can also be injection molded, however, onto shaft16formed, for example, of steel. Alternatively, shaft16can be made at least partially continuous, valve body15,20being mounted on it rotatably and pivotably relative to the axis of shaft16. Alternatively, disc-shaped valve body15,20can be attached axially movably to said shaft16.

An outer contour or an inner contour, which represent a positive-locking connection to an electric drive (not shown further), can be formed at one or at both ends of shaft16of valve body15,20.

Valve body15or20, furthermore, can be under preload by means of mechanical, preferably resilient elements against one or more of the openings of connecting pieces13,14as a whole, i.e., together with shaft16or only on shaft16itself, if valve body15and shaft16are made separately. Due to this preloading, valve body15or20can perform an adjusting movement in the case of a wearing seal and thus a specified leakage is not exceeded over the lifetime of valve2.

Advantageously, the mechanical, particularly resilient element is designed such that with a completely closed valve2(e.g., coolant is in warm-up) and simultaneously high speed of pump7and thus a high applied hydraulic differential pressure, valve body15or20is pushed away from the seal (not shown further) and coolant can thus flow. This is helpful particularly whenever during a cold start the driver of the motor vehicle immediately reaches a high speed, as a result of which critical temperatures or local temperature peaks can occur in the internal combustion engine or cavitation can arise on the intake side of pump7.

The sealing against valve body15,20can also occur by seals introduced into housing11. These can be injection molded or inserted mechanically. The seals are elastomers, preferably EPDM (ethylene-propylene-diene rubber) or HNBR (hydrogenated acrylonitrile-butadiene rubber). There are advantageously coated with a friction-reducing material such as PTFE or Parylene or the outer layers of the elastomer contain said compounds. Elastomers can also be used, however, to press a friction-optimized sealing material, e.g., PTFE, elastically against valve body15,20.

Preferably, however, a combination of the setting of the spring preload and an adjusting seal can also be used.

To assure the operational safety of cooling circuit1in the case of failure of valve2, an expanding wax thermostat21is inserted into valve2, as is shown inFIG. 6. The expanding wax thermostat operates here as a fail-safe mechanism. Such expanding wax thermostats21assure that there is sufficient cooling of the internal combustion engine when a critical temperature is reached with the simultaneous failure of normal valve operation. Such an expanding wax thermostat21is directly dependent on its temperature and thus on the coolant temperature and flow velocity of the coolant around the thermostat. When a critical temperature is reached, the expanding material melts, as a result of which valve2is actuated by the expansion of the material's volume during melting. The position of expanding wax thermostat21in housing11is thereby independent of whether the valve is used as ingress regulator2or as egress regulator3. When used as an ingress regulator, expanding wax thermostat21connects the radiator return inlet to pump7or engine outlet4(FIG. 6a). When used as an egress regulator, thermostat21connects engine outlet4to radiator inflow8of valve2(FIG. 6b).

As already explained, the driving of valve body15or20occurs via an electric motor, which is disposed in an actuator unit together with a gear unit and a sensor for feedback on the position of valve body15,20. The electric motor is thereby advantageously a DC motor. Preferably, said actuator unit is attached as an independent part to valve2. It is especially advantageous in this case, if an outer housing wall of the actuator unit at the same time forms an inner side of housing11of valve2. Thus, on the one hand, the material required for the valve housing can be reduced but, on the other, the number of parts for valve2can also be reduced in that, e.g., the shaft bearings and shaft sealing need not be inserted into housing11of valve2up to the actuator, because they are typically already present in the actuator unit.

The feedback on the position of valve body15,20occurs via a Hall sensor. A Hall switch, which takes a relative measurement of the position of valve body15,20for one or more end positions, but preferably of reference points represented by magnets, can also be used as a cost-effective alternative.

The described valve2, which because of its simple structure can be used both as an ingress regulator and as an egress regulator in a cooling circuit, can be configured thereby so that only the two switching states, open and closed, are realized. Preferably, however, any desired intermediate state can be realized, especially continuously. Valve2therefore is a control element, which depending on the desired operating temperature of one or more parts adjusts the temperature of the coolant by controlling the volumetric flow of the coolant, whereby the volumetric flow can flow over one or more warmer circuits (e.g., bypass circuit) and/or over one or more cooler circuits (e.g., radiator circuit).

A temperature sensor can be disposed in the housing of valve2. It is possible, further, to dispose the valve together with a coolant pump in a mutual housing.