GB2349919A

GB2349919A - Hydraulic unit

Info

Publication number: GB2349919A
Application number: GB0009585A
Authority: GB
Inventors: Roland Kasaj; Kai Lehmann
Original assignee: DaimlerChrysler AG
Current assignee: Daimler AG
Priority date: 1999-05-08
Filing date: 2000-04-18
Publication date: 2000-11-15
Anticipated expiration: 2020-04-18
Also published as: FR2794818A1; GB0009585D0; DE19921436A1; GB2349919B

Abstract

In a hydraulic unit, a pressure tank 2 in which a hydraulic medium 6 is stored and can be pressurized is designed as a support housing, to which all the other parts of the hydraulic unit are attached in such a way that the hydraulic unit forms an assembly unit which can be mounted completely assembled. In addition, a hydraulic-medium pump 7, which delivers the hydraulic medium from the pressure tank 2 or into the pressure tank, an electric motor 11, which drives the hydraulic-medium pump, and a control device 14, which contains a control for actuating the electric motor 11, each have a separate housing 12, 13, 14 containing all the components of the respective part to form a module which can be mounted completely assembled. In this case, at least hydraulic medium pressuriser 3, which, and the pump module 7 are attached in the interior of the pressure tank 2 and the other modules 11, 14 are attached to the pressure tank 2 on the outside.

Description

1 2349919 Hydraulic unit The invention relates to a hydraulic unit for

supplying a hydraulic consumer in motor vehicles, having a pressure tank in which a hydraulic medium is stored, the medium being pressurizable, an accumulator which stores pressure in the form of potential energy and thus puts the hydraulic medium of the pressure tank under this pressure, a hydraulic-medium pump which delivers the hydraulic medium from the pressure tank or into the pressure tank, an electric motor which drives the hydraulic-medium pump, and a control which actuates the electric motor.

Such a hydraulic unit has been disclosed, for example, by DE 37 26 979 AI which shows a pressure tank in which a hydraulic medium is stored and can be pressurized. In this case, the pressure tank is formed by a first chamber of a cylinder in which a piston is axially adjustable and axially separates two chambers in the cylinder. In this arrangement, the second chamber of this cylinder forms an accumulator which can be charged pneumatically and stores the pressure prevailing therein in the form of potential energy and which puts the hydraulic medium of the pressure tank under this pressure via the adjustable piston. In addition, the known hydraulic unit has a hydraulic -medium pump which delivers the hydraulic medium. from the pressure tank or into the pressure tank, an electric motor which drives the hydraulic-medium pump being provided. Finally the hydraulic unit has a control which serves to actuate the electric motor.

The known hydraulic unit has a support housing of complicated design, in which the pressure tank, the accumulator, the hydraulic-medium pump and the electric motor are accommodated. In this case, a housing of the hydraulic-medium pump is formed in one piece with the support housing and a cover of the support housing serves as a housing for the electric motor. By means of these measures, the individual parts of the hydraulic unit are integrated in the design of the support housing, as a result of which an especially compact type of construction is obtained. With this integrated construction, the known hydraulic unit is optimized for a certain application with a certain demand profile, in particular for a certain vehicle type. However, if the known hydraulic unit has to be adapted to another demand profile, in particular if the hydraulic unit is to be used in another vehicle type, this is not readily possible. For example, both a small car and a large saloon are to be equipped with such a hydraulic unit. So that this is possible, two different 2 hydraulic units can be provided, of which the one is optimized for the small car and the other is optimized for the large saloon. However, this involves high manufacturing costs. As an alternative to this, a single hydraulic unit which can fulfil both performance profiles may be used in both vehicle types. The hydraulic unit is then normally overrated for many of its applications, as a result of which increased costs occur here too. In addition, the installation space for a hydraulic unit which has the performance profile for a large saloon is often lacking in a small car.

In particular during the vehicle manufacture, which normally takes place within the scope of large-scale production, it is essential to offer a wide range of models on the one hand and to keep the manufacturing costs required for this as low as possible on the other hand.

The present invention deals with the problem of configuring a hydraulic unit of the type mentioned at the beginning in such a way that the costs of designing different variants are reduced.

According to the present invention there is provided a hydraulic unit for supplying a hydraulic consumer in motor vehicles, having a pressure tank in which a hydraulic medium is stored, the medium being pressurizable, an accumulator which stores pressure in the form of potential energy and thus puts the hydraulic medium of the pressure tank under this pressure, a hydraulic-medium pump which delivers the hydraulic medium from the pressure tank or into the pressure tank, an electric motor which drives the hydraulic-medium pump, and a control which actuates the electric motor, wherein, the pressure tank is a support housing, to which all the parts of the hydraulic unit are attached in such a way that the hydraulic unit forms an assembly unit adapted to be mounted completely assembled, the control being accommodated in a control device, and the parts of the control device, hydraulic-medium pump and electric motor each having a separate housing containing all the components of the respective part and forming a module which is adapted to be mounted completely assembled, and at least the accumulator and the pump module are attached in the interior of the pressure tank and the other modules are attached to the pressure tank on the outside.

The invention is based on the general idea of constructing the hydraulic unit in a modular manner, in which case the pressure tank at the same time serves as support 3 housing, to which the individual modules are attached. Of particular importance in this case is the proposal that each module has a separate housing in which or on which all the components of the respective module are arranged, as a result of which the respective module forms an assembly unit which can be mounted completely assembled. By means of this measure, the respective hydraulic unit can be assembled quickly and with standardized assembly operations according to the modular construction principle in accordance with the respective demand profile. If, for example, a hydraulic-unit variant requires a more powerful electric motor, an electric-motor module which contains an electric motor having the required power is used during the assembly of the hydraulic unit. Since the hydraulic unit can be adapted to different demand profiles in a simple manner by exchanging individual modules, the costs required for this are relatively low. The hydraulic unit according to the invention is distinguished by high flexibility and adaptability to different demand and performance profiles, in particular to different installation conditions.

In an advantageous embodiment, in addition to the pump module, the motor module may also be arranged in the interior of the pressure tank, so that a drive shaft of the electric motor need not be passed through the outer wall of the pressure tank. In addition, the electric motor may then also be designed in a simpler manner as a so-called "wet runner", in which case leakages are not a problem. In such an embodiment, the pump module is preferably mounted on the motor module and the motor module is preferably mounted on the pressure tank, so that it is not important which motor module is used for the attachment of the pump module.

Further important features and advantages of the hydraulic unit according to the invention follow from the subclaims, the drawings and the associated description of the figures with reference to the drawings.

It goes without saying that the abovementioned features and the features still to be explained below can be used not only in the combination specified in each case but also in other combinations or on their own without departing from the scope of the invention.

Preferred embodiments of the invention are shown in the drawings and explained in more detail in the following description.

In the drawing, in each case schematically:

Fig. I shows a diagrammatic representation of a first embodiment of a hydraulic unit according to the invention, 4 Fig. 2 shows a diagrammatic representation as in Fig. 1 but of a second embodiment of the hydraulic unit according to the invention, Fig. 3 shows a diagrammatic representation as in Fig. 1 but of a third embodiment of the hydraulic unit according to the invention.

In accordance with Figs. 1 to 3, a hydraulic unit 1 according to the invention has a pressure tank 2 which is designed as a support housing for the entire hydraulic unit 1. For this purpose, the pressure tank 2 is provided with conventional fastening means (not shown). Arranged in the interior of the pressure tank 2 is an accumulator 3, which is designed as a diaphragm or bladder accumulator and is shown symbolically in Figs. 1 to 3 by a diaphragm 5 which can be inflated via a valve 4. Furthermore, a hydraulic medium 6, e.g. hydraulic oil, which can be pressurized by the accumulator 3, is located in the pressure tank 2. For this purpose, the diaphragm 5 is filled with a gas, e.g. air, via the valve 4 until the desired pressure is set.

In addition, a hydraulic-medium pump 7, in particular a gear or vane pump, is accommodated in the interior of the pressure tank 2 and has a first connection 8, by means of which the pump 7 communicates with the interior of the pressure tank 2. The pump 7 also has a second connection 9, which is connected to a line 10 led out of the pressure tank 2. The pump 7 is designed as a module (pump module 7) and to this end has a pump housing 12 in which all the components of the pump 7 are integrated, so that the pump module 7 forms an assembly unit which can be mounted completely assembled.

The pump 7 is designed for bi-directional delivery, so that it can deliver hydraulic medium 6 both out of the pressure tank 2 and into the pressure tank 2. This bi-directional mode of operation of the pump is indicated by double arrows a at the connections 8 and 9 or at the line 10.

In addition, the hydraulic unit 1 according to the invention has an electric motor 11, which is in drive connection with the pump 7. The electric motor 11 is also designed as a module (motor module 11), for which purpose the electric motor 11 has a motor housing 13 in which all the components of the electric motor 11 are integrated, so that the motor module 11 also forms an assembly unit which can be mounted completely assembled.

To actuate the hydraulic unit 1 or the electric motor 11 and thus the pump 7, a control device 14, which is connected to the motor module 11, is provided. The control device 14 has a device housing 15 in which all the components, in particular a corresponding control, of the control device 14 are integrated, so that the control device 14 is also designed as a module (control module 14) and constitutes an assembly unit which can be mounted completely assembled. Connected to the control module 14 are powersupply leads 16, via which the hydraulic unit 1 is supplied with electrical energy.

In accordance with Fig. 1, the motor module 11, in a first embodiment, is arranged on the outside of the pressure tank 2 and is in drive connection with the pump module 7 through a wall 17 of the pressure tank 2. Here, the pump 7 has a leakage port 18 through which a leakage quantity collecting in the pump module 7 can escape into the pressure tank 2.

In a second embodiment, the motor module 11, according to Fig. 2, is also attached in the interior of the pressure tank 2, the control module 14 in this case being attached to the motor module I I through the wall 17 of the pressure tank 2. The pump module 7 here is directly connected to the motor module 11. In the embodiment shown in Fig. 2, the motor module I I is provided with a leakage port 19 through which a leakage quantity collecting at the pump 7 and at the electric motor I I can escape into the pressure tank 2. Whereas the electric motor I I in the embodiment in accordance with Fig. I is preferably designed as a so-called "dry runner", the electric motor I I in the embodiment shown in Fig. 2 can preferably be a so-called "wet nmner". Seating problems do not occur in this case, since both the electric motor 11 and the pump 7 are arranged completely inside the pressure tank 2.

In the embodiments according to Figs. I and 2, the hydraulic unit communicates via the line 10 with a hydraulic consumer (not shown), e.g. with a travel-mechanism actuator, and, according to requirements, can feed hydraulic medium 6 to or discharge it from this actuator in order to set the desired hydraulic pressure in the respective actuator. The hydraulic medium 6 contained in the pressure tank 2 is statically prestressed by the accumulator 3, so that the pump 7 can work at a higher pressure level.

In accordance with Fig. 3, the motor module 11, in a third embodiment of the hydraulic unit according to the invention, is again arranged on the outside of the pressure tank 2. Here, the leakage port 18 is connected to a line 20 led out of the pressure tank 2. In addition, a valve 21, which may also be designed as a module, is attached to the pressure tank 2.

Unlike the embodiments described above, in the embodiment described in Fig. 3 a hydraulic-medium consumer is preferably supplied with hydraulic medium or with hydraulic pressure via the valve 2 1. In this case, the pump 7 essentially serves only to refill the pressure tank 2 or to maintain the pressure level in the pressure tank 2.

6 Accordingly, the line 10 communicates, for example, with a relatively pressureless hydraulic-medium reservoir (not shown), the line 20 also preferably being connected to this hydraulic-medium reservoir in order to draw off the leakage relative to a lower pressure level.

It is obvious that, to attach the pump module 7 to the pressure tank 2 (Figs. I and 3) or to the motor module 11 (Fig. 2) and for the attachment of the motor module I I to the pressure tank 2 (Figs. I to 3) or to the pump module 7 (Fig. 2) and also for the attachment of the control module 14 to the motor module I I (Figs. I and 3) or to the pressure tank 2 (Fig. 2), corresponding interfaces which permit simple mounting of the modules 7, 11, 14 are formed at the respective parts. According to the circumstances, these interfaces contain mechanical fastening means and/or mechanical drive coupling means and/or electrical connecting means. The advantages of the hydraulic unit I of modular construction are of particular importance when there are a plurality of variants of the one or the other module 7, 11, 14, which can be combined with one another in any desired manner. For example, it is especially simple to motorize the hydraulic unit I in a different manner by mounting the appropriate motor module I I in each case in order to assemble the hydraulic unit 1. It is obvious that the aforesaid interfaces between the individual parts of the hydraulic unit I are standardized to the extent that it makes no difference for the assembly whether the one module variant or another module variant is mounted.

Claims

7 Claim

1. A hydraulic unit for supplying a hydraulic consumer in motor vehicles, having a pressure tank in which a hydraulic medium is stored, the medium being pressurizable, an accumulator which stores pressure in the form of potential energy and thus puts the hydraulic medium of the pressure tank under this pressure, a hydraulic-medium pump which delivers the hydraulic medium from the pressure tank or into the pressure tank, an electric motor which drives the hydraulic-medium pump, and a control which actuates the electric motor, wherein, the pressure tank is a support housing, to which all the parts of the hydraulic unit are attached in such a way that the hydraulic unit forms an assembly unit adapted to be mounted completely assembled, the control being accommodated in a control device, and the parts of the control device, hydraulic-medium pump and electric motor each having a separate housing containing all the components of the respective part and forming a module which is adapted to be mounted completely assembled, and at least the accumulator and the pump module are attached in the interior of the pressure tank and the other modules are attached to the pressure tank on the outside.

2. A hydraulic unit according to Claim 1, wherein the motor module is likewise arranged in the interior of the pressure tank, the pump module being mounted on the motor module and the motor module being mounted on the pressure tank.

3. A hydraulic unit according to Claim 1 or 2, wherein a heat exchanger is attached to the pressure tank, which heat exchanger has a housing containing all the components of the heat exchanger and forms a module which can be mounted completely assembled.

4. Hydraulic unit according to any one of Claims 1 to 3, wherein an actuating element is attached to the pressure tank or to the pump module, which actuating element has a housing containing all the components of the actuating element and forms a module adapted to be mounted completely assembled.

8 A hydraulic unit according to any one of Claims 1 to 4, wherein the hydraulicmedium pump delivers the pressurized hydraulic medium from the pressure tank to a consumer or from a consumer into the pressure tank.

6. A hydraulic unit according to any one of Claims 1 to 4, wherein the pressure tank has an outlet which is controllable by a control valve and with which the pressurized hydraulic medium can be delivered in a controlled manner from the pressure tank to a consumer or from a consumer into the pressure tank, the hydraulic-medium pump delivering hydraulic medium as required between a hydraulic-medium reservoir and the pressure tank, 7. A hydraulic unit according to any one of Claims 1 to 6, wherein the accumulator comprises a diaphragm or bladder accumulator or piston accumulator.

8. A hydraulic unit for supplying a hydraulic consumer in motor vehicles, substantially as described herein with reference to, and as illustrated in, the accompanying drawings.