Patent Description:
It is generally known that power units (drive motors, transmissions, clutches or combinations of these components) have an oil circuit which supplies oil to the bearing points and components requiring lubrication. In a simple example, a collection tank (oil sump) is provided from which oil is extracted by an oil pump and conveyed to the components to be lubricated or cooled. From there, the oil returns to the collection tank under the effect of gravity.

It is also known that in sporting vehicles which travel under high transverse acceleration for longer periods, additional measures are required to guarantee that sufficient oil can be delivered by the oil pump at all times, even on lengthy cornering. In this context, it is known to divide the collection tank into several part volumes and provide the oil pump with several suction pipes which extract oil from different locations in the oil tank, and/or to use flaps and valves to guarantee that under the effect of centrifugal force, the oil cannot flow out of the region from which it is extracted by the oil pump. <CIT> discloses such an oil pump system.

The object of the invention is to create an oil supply system with which oil can be reliably conveyed to the power unit even under high transverse acceleration over a lengthy period, without the need for valves, flaps or other moving components in the oil supply system.

To achieve this object, according to the invention an oil supply system is provided for a machine, in particular for a power unit of a motor vehicle, with a module body made of plastic comprising a collection tank which is divided into a prechamber and a main chamber, a predelivery pump which can extract oil from the prechamber and pump it into the main chamber, a main delivery pump which can extract oil from the main chamber and pump it to the machine, and a return line which can return oil from the machine to the prechamber and/or the main chamber. The invention is based on the fundamental idea of supplying the main chamber with the oil returned from the machine in two different ways: Part of the oil may reach the main chamber directly from the return line, and another part which reaches the prechamber is pumped into the main chamber by means of the predelivery pump. This guarantees that, under all operating conditions, a sufficiently high oil level is present there for the main delivery pump to be able to deliver the desired volume flow of oil to the machine.

The collection tank may be divided into the prechamber and main chamber by a partition wall, so that the two chambers can be created with low structural complexity and production cost.

The predelivery pump and the main delivery pump are mounted on the module body.

According to an embodiment of the invention, it is provided that the capacity of the main chamber is smaller than the capacity of the prechamber. As a result, the fill height of the main chamber is in principle comparatively high, so that the main delivery pump can extract oil under all operating conditions,.

According to an embodiment of the invention, a main delivery suction opening which is connected to the suction side of the main delivery pump is arranged substantially centrally on the floor of the main chamber. Because of the comparatively low volume of the main chamber, it is guaranteed that even under high transverse and longitudinal acceleration, the main delivery suction opening is covered with oil at all times.

Furthermore, a predelivery suction opening may be provided, which is connected to the suction side of the predelivery pump and arranged on an outside of the floor of the prechamber. The position of the predelivery suction opening is preferably selected such that it is covered with oil during such transverse acceleration, wherein a large part of the oil enters the prechamber and not the main chamber via the return line. The oil returned to the prechamber is then pumped by the predelivery pump into the main chamber, from where it can be delivered to the machine by the main delivery pump.

The predelivery pump and the main delivery pump may be configured as separate pumps which can be actuated as required with respect to the volume flow conveyed.

According to the invention the predelivery pump and main delivery pump are combined in one module or pump unit. According to one embodiment, it is possible for the predelivery pump and the main delivery pump to be integrated into a double-flow pump. For example, the rotor of the predelivery pump may be arranged on the same shaft as the rotor of the main delivery pump. According to the invention, the predelivery pump and the main delivery pump are driven by a common electric motor.

According to a preferred embodiment, it is provided that the predelivery pump and the main delivery pump are implemented by a rotary vane pump, in which the main delivery pump is formed by the pressure chambers defined between the adjacent rotary vanes, and the predelivery pump is formed by the pressure chambers defined between a rotor and the end face of the rotary vanes received in the rotor. Such a pump is very compact, so little space is required.

According to the invention, the module body further comprise a heat exchanger, a temperature sensor and a filter element mounted on the module body.

The invention also concerns a power unit for a motor vehicle with an oil supply system of the type described above, wherein a predelivery suction opening is arranged on the floor of the prechamber and a main delivery suction opening is arranged on the floor of the main chamber, and the power unit is configured to be mounted in the motor vehicle with an orientation such that a line running through the two suction openings is arranged approximately parallel to the transverse axis of the vehicle. With this orientation, there is a "right" chamber and a "left" chamber, one of which is a prechamber and the other a main chamber, and which, under high transverse acceleration of the vehicle, return the oil to the oil tank in different ways, as explained above.

The invention will be described below on the basis of an embodiment which is illustrated in the appended drawings. In the drawings:.

<FIG> show an oil supply system <NUM> which can supply a machine with oil. The oil may be used for lubrication and/or cooling. The machine may for example be a power unit for a motor vehicle which comprises for example an electric motor, a transmission and a clutch.

The power unit is not shown here as it is not relevant for understanding of the oil supply system. Only two interfaces <NUM>, <NUM> between the oil supply system <NUM> and the machine it supplies are relevant here, namely a supply interface <NUM> at which oil is delivered from the oil supply system to the machine, and a return interface <NUM> via which the oil is returned from the machine to the oil supply system.

The oil supply system <NUM> has a module body <NUM> (see <FIG>) which in the exemplary embodiment shown consists of plastic. The various components of the oil supply system <NUM> which will be explained below are integrated in the module body <NUM>.

A collection tank <NUM>, which may for example be configured in the manner of an oil sump, is formed inside the module body <NUM>.

A partition wall <NUM> is arranged inside the collection tank <NUM> and divides the inner volume of the collection tank <NUM> into a prechamber <NUM> and a main chamber <NUM>.

The partition wall <NUM> does not extend up to the upper boundary of the collection tank <NUM>, so that under certain circumstances, oil can flow over the partition wall <NUM> from one chamber to the other.

A predelivery suction opening <NUM> is provided on the floor of the prechamber <NUM>. and is connected via a suction line <NUM> to a suction side <NUM> of a predelivery pump <NUM>. The predelivery pump <NUM> conveys oil extracted from the prechamber <NUM> into the main chamber <NUM>.

A main delivery suction opening <NUM> is provided on the floor of the main chamber <NUM>, and is connected via a suction line <NUM> to a suction side <NUM> of a main delivery pump <NUM>.

As <FIG> shows, the volume of the main chamber <NUM> is smaller than the volume of the prechamber <NUM>. In addition, the main delivery suction opening <NUM> is arranged approximately centrally on the floor of the main chamber <NUM>. It is therefore guaranteed that, irrespective of the side on which the oil collects in the main chamber <NUM>, the main delivery suction opening <NUM> is always reliably covered with oil.

The suction opening <NUM> however is not arranged centrally on the floor of the prechamber <NUM>, but on the outside on the side facing away from the main chamber <NUM>.

Furthermore, the two suction openings <NUM>, <NUM> are arranged on opposite outer sides with respect to the collection tank <NUM> as a whole. Since the prechamber <NUM> has a larger volume than the main chamber <NUM>, the prechamber suction opening <NUM> is arranged eccentrically on the outside of the floor of the prechamber <NUM>, while the main delivery suction opening <NUM> is arranged centrally on the floor of the prechamber <NUM>.

In principle, separate pumps may be used for the predelivery pump <NUM> and the main delivery pump <NUM>. However, a double-flow pump is preferred, in particular of the type shown in <FIG>. The rotary vane pump shown there is explained in more detail below. With reference to <FIG>, the only relevant factor is that it is driven by an electric motor <NUM>.

The electric motor <NUM>, together with the predelivery pump <NUM> and the main delivery pump <NUM>, forms a compact oil pump assembly <NUM>.

As <FIG> shows, the oil pump assembly <NUM> is arranged on or integrated in the module body <NUM>.

The main delivery pump <NUM> conveys the oil out of the main chamber <NUM> towards the supply interface <NUM> via pressure side <NUM> of the main delivery pump <NUM>. Here, a heat exchanger <NUM>, a temperature sensor <NUM> and a filter element <NUM> may also be provided within the oil supply system <NUM>. By means of the heat exchanger <NUM> and a coolant stream K, which is indicated purely schematically here (see the supply and outlet designated jointly in <FIG> with reference sign <NUM>), the temperature of the oil delivered to the machine can be controlled. The volume flow of the coolant may be controlled depending on a signal of the temperature sensor <NUM>. The filter element <NUM> guarantees that no contaminants are supplied to the machine together with the oil.

The heat exchanger <NUM> has a housing of metal (in the exemplary embodiment shown, an aluminium alloy) and is arranged on the outside of the module body <NUM>.

The filter element <NUM> is integrated in the module body <NUM>.

The oil from the machine returns to the collection tank <NUM> via the return interface <NUM>. A return line <NUM> provided for this purpose has two outlets <NUM>, <NUM>, namely an outlet <NUM> into the prechamber <NUM> and an outlet <NUM> into the main chamber <NUM>.

The two outlets <NUM>, <NUM> are here indicated schematically. They need not necessarily be provided on a single return line <NUM>, but may form the end points of two completely separate return lines, for example one from a right side of the machine and one from a left side of the machine, back into the oil supply system <NUM>.

Assuming that no significant acceleration forces (i.e. neither transverse acceleration from cornering nor longitudinal acceleration from acceleration or braking processes) act on the oil supply system <NUM>, the oil returned via the return interface <NUM> is returned partly to the prechamber <NUM> and partly to the main chamber <NUM>. The part reaching the prechamber <NUM> is pumped via the predelivery pump <NUM> into the main chamber <NUM>, from where it is conducted to the supply interface <NUM> via the main delivery pump <NUM>.

If the two suction openings <NUM>, <NUM> are arranged along a line which corresponds substantially to the transverse axis of the vehicle, and if we now assume that the vehicle in which the oil supply system <NUM> is installed is travelling around a corner such that the centrifugal forces are directed to the right relative to <FIG>, an oil level as indicated with the dotted line <NUM> is obtained in the prechamber <NUM> and main chamber <NUM>.

It can furthermore be assumed that, in the entire return circuit, the oil is rather pushed to the right in the same way as in the collection tank <NUM>, that the oil largely reaches the collection tank <NUM> via the return opening <NUM>, that is into the prechamber <NUM>.

As the predelivery suction opening <NUM> is not arranged centrally on the floor of the prechamber <NUM> but on the right-hand side, it is ensured that oil can easily be extracted out of the prechamber <NUM> since it collects on the right-hand side of the prechamber <NUM> under the acceleration forces applicable here.

In this operating state, there are no negative effects if the majority of the oil enters the collection tank via the return opening <NUM> and not via the return opening <NUM>, since the predelivery pump <NUM> guarantees that the oil nonetheless reaches the main chamber <NUM> from where it can be pumped to the supply interface <NUM> by the main delivery pump <NUM>.

<FIG> shows the oil supply system from <FIG> in an operating state in which the acceleration acts in the opposite direction to the acceleration assumed in <FIG>. Accordingly, the oil collects on the left-hand side of the prechamber <NUM> and the main chamber <NUM>.

It can be seen that part of the oil runs directly over the partition wall <NUM> and reaches the main chamber <NUM> in this way. Furthermore, a large part of the oil then flows directly into the main chamber <NUM> via the return opening <NUM>. For this reason, there are no negative effects if the predelivery suction opening <NUM> is not covered with oil, and therefore the predelivery pump <NUM> does not pump oil into the main chamber <NUM>. The oil reaches the main chamber <NUM> either via the return opening <NUM> or, if the fill level of the prechamber <NUM> is high enough, directly over the partition wall <NUM>, and from there it is pumped to the supply interface <NUM> by the main delivery pump <NUM>.

<FIG> shows schematically a dual pump with which the predelivery pump <NUM> and main delivery pump <NUM> are combined into a single pump.

This is a rotary vane pump or vane pump with a stator <NUM> in which an interior space <NUM> is formed which is surrounded by an inner wall <NUM>.

A rotor <NUM> is arranged in the interior of the stator <NUM> and is mounted on a shaft <NUM> and can be driven by the latter.

The rotor <NUM> is provided with multiple receptacles <NUM>, in which in each case one rotary vane <NUM> is received.

The receptacles <NUM> extend in the axial direction normally from a face side of the rotor <NUM> as far as the opposite face side, and from the outer periphery of the rotor inwards. In the exemplary embodiment shown, the receptacles <NUM> extend in the radial direction. This is not necessary, however.

Here, the rotary vanes are in the form of plates whose dimension in the radial direction is slightly less than the radial depth of the receptacles <NUM>. Each of the plates has a thickness b, which corresponds to the width of the receptacles <NUM>.

As an alternative to plate-like rotary vanes, use may also be made of rotary vanes which are in the form of a cylinder.

The rotor <NUM> has a diameter of <NUM> x r (minus a clearance between rotor and stator that is to be provided in the design), which is less than the diameter r+R of the interior space <NUM> of the stator <NUM>. The rotor <NUM> is arranged eccentrically in the interior space, specifically such that it is (almost) in contact with the inner wall <NUM> on one side (at the <NUM> o'clock position in this case). Accordingly, the maximum spacing to the outer wall of the rotor <NUM> is on the diametrically opposite side.

The rotary vanes <NUM> bear with their radially outer side <NUM> permanently against the inner wall <NUM> of the stator <NUM> (at any rate when the rotor <NUM> is rotating). Consequently, between rotary vanes <NUM> adjacent to one another in the peripheral direction, the inner wall <NUM> of the stator <NUM>, the outer wall of the rotor <NUM> and two side walls which close off the interior space <NUM> at the face sides of the rotor <NUM> (and of which only the "rear" side wall <NUM> can be seen here), in each case one low-pressure chamber <NUM> is delimited. The function of the main delivery pump <NUM> is achieved with the pressure chambers.

In the exemplary embodiment shown, since five rotary vanes <NUM> are present, it is also the case that five pressure chambers <NUM> are formed. On a rotation of the rotor <NUM> through <NUM>°, the volume of each individual pressure chamber changes from a minimum value (when the pressure chamber <NUM> is approximately at the <NUM> o'clock position) via a maximum value (when the pressure chamber <NUM> is approximately at the <NUM> o'clock position) and back to the minimum value.

The pressure chambers <NUM> are supplied with hydraulic fluid through the inlet <NUM> which is connected to the suction side <NUM>. Said inlet <NUM>, viewed in the direction of rotation of the rotor <NUM>, is situated behind the point at which the spacing between the outer surface of the rotor <NUM> and the inner wall <NUM> of the stator <NUM> is minimal.

The hydraulic fluid drawn in by the pressure chambers <NUM> via the inlet <NUM> is discharged via a pressure outlet <NUM>, which, viewed in the peripheral direction, is behind the position at which the pressure chambers <NUM> have the maximum volume, but in front of the position at which the spacing between the outer side of the rotor <NUM> and the inner wall <NUM> of the stator <NUM> is minimal. The pressure outlet <NUM> then leads to the supply interface <NUM>.

The inlet <NUM> and the pressure outlet <NUM> are arranged here in one of the side walls <NUM> of the hydraulic pump or also, so as to improve the filling, in both side walls <NUM>, so that the hydraulic fluid can be drawn into or expelled from the pressure chamber <NUM> on both sides.

Each of the rotary vanes <NUM>, together with the rotor <NUM> (and also the side walls <NUM>), delimits a respective predelivery pump pressure chamber <NUM>. Specifically, each radially inner side <NUM> of each rotary vane <NUM>, together with the walls of the receptacle <NUM> and the side walls <NUM> shown, delimits a respective predelivery pump pressure chamber <NUM>.

The volume of the predelivery pump pressure chambers <NUM> changes according to the displacement of the rotary vanes <NUM> in the receptacles <NUM>. When the rotary vanes <NUM> move outwards (i.e. during a movement from the <NUM> o'clock position to the <NUM> o'clock position via the <NUM> o'clock position in the exemplary embodiment shown), the volume of the predelivery pump pressure chambers <NUM> increases, and when the rotary vanes <NUM> move inwards (i.e. during a movement from the <NUM> o'clock position to the <NUM> o'clock position via the <NUM> o'clock position), the volume decreases.

In this way, a piston pump is formed in which the radially inner side <NUM> of each rotary vane <NUM> may be regarded as the end face of a pump piston which is moved by means of a curved path (of the inner wall <NUM> of the stator <NUM>). For suction, the pump piston is moved outwards under the action of centrifugal force, and for expulsion, the pump piston is displaced inwards owing to the contour of the inner wall <NUM> of the stator <NUM>.

The predelivery pump pressure chamber <NUM> draws in oil via a pre-pump pressure inlet <NUM> which is connected to the suction side <NUM>.

A predelivery pump pressure outlet <NUM> which is separate from the pressure outlet <NUM> is provided on the pressure side <NUM> of the predelivery pump <NUM>. In the peripheral direction, said pressure outlet is arranged approximately at the same position as the pressure outlet <NUM> and leads into the main chamber <NUM>.

Claim 1:
Oil supply system (<NUM>) for a machine, in particular for a power unit of a motor vehicle, with a module body (<NUM>) made of plastic comprising a collection tank (<NUM>) which is divided into a prechamber (<NUM>) and a main chamber (<NUM>), a predelivery pump (<NUM>) which can extract oil from the prechamber (<NUM>) and pump it into the main chamber (<NUM>), a main delivery pump (<NUM>) which can extract oil from the main chamber (<NUM>) and pump it to the machine, and a return line (<NUM>) which can return oil from the machine to the prechamber (<NUM>) and/or the main chamber (<NUM>), characterized in that the predelivery pump (<NUM>) and the main delivery pump (<NUM>) are driven by a common electric motor (<NUM>) forming a compact oil pump assembly (<NUM>) and this oil pump assembly (<NUM>) is arranged on or integrated in the module body (<NUM>).