DE102015210876A1 - Hydrostatic actuator system - Google Patents

Abstract

The invention relates to a hydrostatic actuator system, in particular for actuating a clutch of a motor vehicle, with a master cylinder, and with a slave cylinder actuated by the master cylinder via a hydraulic path, wherein the master cylinder is arranged according to the invention at a same or a lower height level than the slave cylinder and the hydraulic line between the master cylinder and the slave cylinder has at least partially two lines, which are designed as a flow line and as a return line.

Description

The invention relates to a hydrostatic actuator system, in particular for actuating a clutch of a motor vehicle.

Clutches of motor vehicles have actuator systems, with the aid of which the clutch is actuated. In addition to mechanical actuator systems via cable and electromechanical actuator systems, especially hydrostatic actuator systems have prevailed.

In this case, a so-called master cylinder is actuated by a pedal device (or by an electric motor operated actuator), which acts on a slave cylinder, through which the vehicle clutch is actuated. Master cylinder and slave cylinder are connected to each other via a hydraulic path, which is able to transfer forces from the clutch pedal to a release system of the clutch and thus to effect an actuation of the clutch.

In the simplest case, master cylinder and slave cylinder are connected to a liquid-carrying line, wherein the liquid flow flows in both directions in the same conduit.

In the publication DE 10 2013 203 593 A1 a hydrostatic actuator system is described which operates with two lines. In this case, a line is used to transport the liquid from the master cylinder to the slave cylinder, the other for the opposite direction. The direction of the flow is in each case pressure-controlled by valves, which make it possible to regulate the throughput.

In addition, different measures are described to achieve temperature compensation. This is necessary for higher demands on the ease of use of the clutch to keep the Tastpunktposition of the clutch when heating the system approximately constant. By means of guide elements arranged in the liquid-conducting chambers, influence is exerted on the flow conditions in the master cylinder and in the slave cylinder in order to obtain the most homogeneous possible temperature distribution in the liquid.

The described technical solution is, as usual in known applications assume that the master cylinder in the vehicle is approximately at the same height as the slave cylinder, or that the master cylinder is arranged above the slave cylinder. In this arrangement, the system vented automatically in the course of the first operations, because gas bubbles in hydraulic systems have the property to rise upwards.

Every fluid-operated system must be vented during commissioning. If this does not happen, this will result in malfunctioning or serious damage to the hydrostatic system.

Gas bubbles tend to rise and collect at the highest point. Therefore, it is expedient to arrange the master cylinder above the slave cylinder and to provide the master cylinder via a sniffer bore with a compensation reservoir. Among other functions of the equalization reservoir, trapped gas bubbles pass out of the hydrostatic system with the aid of this.

The object of the invention is to develop a hydrostatic actuator system, in particular for actuating a clutch of a motor vehicle, which.

It allows space-dependent to arrange the master cylinder at any height level, which is equal to or lower than the height level of the slave cylinder and thereby to ensure reliable ventilation.

This object is achieved with the characterizing features of the first claim.

Advantageous embodiments emerge from the subclaims.

The hydrostatic actuator system is used in particular for actuating a clutch of a motor vehicle and has a master cylinder and an operable by the master cylinder hydraulic cylinder slave cylinder, wherein the master cylinder is arranged according to the invention at a same or a lower height level than the slave cylinder and the hydraulic distance between the Master cylinder and the slave cylinder has at least partially two lines, which are designed as a flow line and a return line.

This makes it possible to arrange the master cylinder below the slave cylinder and long lines and slave cylinder located above the master cylinder to permanently free from gas inclusions during operation.

The master cylinder is advantageously arranged in an oil sump in a transmission housing, whereby the sniffing channel ends directly in the surrounding operating medium / hydraulic medium and the otherwise necessary reservoir can be omitted. The arrangement within a gear housing also allows the waiver of corrosion protection measures.

Advantageously, the return line and the supply line extend in at least a portion of the bottom of the master cylinder up to the slave cylinder and preferably parallel to each other. It is advantageous if the flow line and the return line of the hydraulic route on the extending from bottom to top portion at least partially substantially perpendicular. While the connection of the cables thus takes place at the top of the slave and bottom of the master cylinder, their cable connection can now be laid over long distances with a freely selectable gradient.

The section with parallel separate flow and return can in principle overcome any height differences. The flow will automatically fill with each encoder operation with pressure fluid and displace air upwards.

Furthermore, in the flow line, a first check valve and in the return line, a second check valve arranged to set the flow direction of the hydraulic medium. The control of the flow direction in the supply and return line is expediently done with classic check valves. At their tightness in the reverse direction are no extreme requirements and their arrangement along the respective wiring harness is arbitrary.

So that the air can be reliably transported downwards in the falling return line and is not overtaken by oil sliding down the wall, the cross section thereof is to be chosen sufficiently small that the flow velocity entrains any gas bubbles in the case of a master piston return stroke or bubbles due to their surface tension Fill channel cross section.

Furthermore, the return line should be formed sufficiently small in the inner diameter such that gas bubbles are taken from the liquid flow in the direction of the master cylinder. For this purpose, diameters below 4mm and vertical pipe passages are particularly suitable.

Preferably, the inner diameter of the return line should therefore be ≤ 4 millimeters.

To the master cylinder, a first line region can connect as a common fluid line, which is divided in the direction of the slave cylinder in flow line and return line.

Alternatively, a second line region can be formed as a common fluid line on the slave cylinder, which is divided in the direction of the master cylinder in flow line and return line. Alternatively, both are possible.

The first check valve and / or the second check valve are advantageously provided with a closing body, which lies in a rest position against a sealing seat of the check valve. As a result, they do not first have to be closed by flowing pressure medium.

In the solution according to the invention, the lower-arranged master cylinder and the slave cylinder are thus connected to one another via two lines. These two lines (supply and return line) are provided either over the entire distance or only a critical section and the lines assigned by suitable check valves each have a flow direction. The fixed flow direction makes it possible to selectively supply pressure medium from the sensor and remove existing gas from the slave cylinder.

Thus, the system can be vented initially only by the movement of the master piston during commissioning and permanently excrete newly registered air or otherwise arising gas bubbles during operation.

According to the invention, the master cylinder is arranged at a lower level than the slave cylinder in an oil sump in the transmission housing. The connection to the slave cylinder via two parallel, in particular vertical lines, flow and return. Both lines are equipped with check valves. When the master cylinder is actuated, the supply line is filled with pressure medium and any air bubbles are displaced upwards. When the master piston return stroke, the air bubbles are transported down the return line. This is ensured by a diameter of less than 4mm designed cable and the vertical line arrangement.

The invention will be explained below using an exemplary embodiment. Showing:

1 a connection of master cylinder and slave cylinder with common supply and return line according to the prior art.

2 an arrangement of master cylinder and slave cylinder according to the prior art, in which the master cylinder is arranged higher than the slave cylinder.

3 an arrangement of master cylinder and slave cylinder, wherein the slave cylinder is located higher than the master cylinder.

1 shows a simplest embodiment of the prior art in a schematic diagram at which is a master cylinder 1 with a slave cylinder 2 through a fluid line 3 is connected, which represents a common supply and return line.

Here is the master cylinder 1 Component of a pedal device, not shown here 4 (or an electric motor operated actuator), while the slave cylinder 2 Part of a coupling, not shown here 5 is.

Is on the master cylinder 1 a force introduced, this generates by the in the fluid line 3 resulting hydrostatic pressure on the slave cylinder 2 an actuating force of the clutch 5 , With relief of the pedal device 4 the hydrostatic medium flows back.

2 shows a classic arrangement of master cylinder 1 and slave cylinder 2 , For the operation of clutches, brakes and similar devices, including positive clutches such as shift sleeves, such arrangements are often with a master cylinder 1 and a slave cylinder 2 used, with the help of a largely incompressible fluid column on the master cylinder 1 Initiated movement (eg by a pedal device, a shift lever, an electric actuator, ...) to the slave cylinder 2 even over longer or winding paths with low friction and reliable transfer. The prerequisite for perfect functioning is that gas bubbles present in the system can be quickly eliminated during commissioning and during operation as well as newly formed gas collections. This is the master cylinder 1 usually arranged higher than the slave cylinder 2 ,

Above the higher-located master cylinder 1 is a storage container 8th with a fluid reservoir 10 (usually a hydraulic medium) provided to the master cylinder 1 a sniff hole 9 leads and thus the Schnüffelbohrung 9 with that in the container 8th located fluid reservoir 10 connected is.

In this arrangement, in addition to the automatic completion of leakage losses of hydrostatic medium automatic ventilation is possible. Gas bubbles from the slave cylinder 2 and throughout the liquid system can enter the liquid reservoir 10 through the sniffer hole 9 rising up. Hydrostatic medium (fluid / hydraulic medium) can flow into the system.

Typically, the non-designated master piston in its rest position is a path between the master cylinder 1 and the reservoir above 8th free. So can gas from the master cylinder 1 in the reservoir 8th ascend and in turn fluid from the fluid reservoir 10 in the master cylinder 1 flow in.

So that gas trapped somewhere in the system to the master cylinder 1 boundary conditions in the arrangement and the routing must be observed, and the master cylinder 1 represent the highest point of the arrangement (eg brake system in the car: master cylinder at the height of the water tank, wheel brake cylinder hub height) and the lines must, except for short passages, total to the master cylinder 1 going uphill.

Since large bubbles in narrow cross sections (less than about 4 mm in diameter) do not necessarily rise by themselves, it must also be ensured that the fluid column in these regions is displaced so far during operation of the system that any bubbles contained can be pushed into regions which they can ascend to not always be pushed back and forth.

3 shows an inventive arrangement of master cylinder 1 and slave cylinder 2 in which the slave cylinder 2 higher than the master cylinder 1 , The master cylinder 1 is for example by a pedal device 4 (or a shift lever, an electric actuator, etc. ...) operated and the slave cylinder 2 operates a clutch 5 ,

The hydraulic route between master cylinder 1 and slave cylinder 2 is divided into a supply line 6 and a return line 7 which are substantially parallel to each other.

The master cylinder 1 is in an oil level, for example, the transmission oil sump of an engine in the motor vehicle, arranged and uses this as a liquid reservoir 10 , Here is the master cylinder 1 over the sniff hole 9 with the existing oil level as a liquid reservoir 10 connected, and the reservoir can be omitted .. The master cylinder 1 but also completely from the liquid reservoir 10 be enclosed. The arrangement within the oil sump, for example, a transmission housing also allows the waiver of corrosion protection measures.

From the master cylinder 1 leads the supply line 6 via a first check valve 11.1 to the slave cylinder 2 , wherein the first check valve 11.1 ensures that the hydraulic fluid through the flow line 6 only in the direction of the slave cylinder 2 flows.

Furthermore, the return line runs 7 via a second check valve 11.2 from the slave cylinder 2 to the master cylinder 1 , This secures the second check valve 11.2 in that the hydraulic medium passes through the return line 6 only in the direction of the master cylinder 2 flows.

The section with parallel separate feed line 6 and return line 7 can in principle overcome any height differences. The supply line 6 will automatically with each actuation of the master cylinder 1 successively fill with pressure fluid and displace air upwards.

So that the air reliably in the falling return line 7 can be transported down and is not overtaken by herabrinnendem oil on the wall, here is the cross-section sufficiently small to choose, so that in a return stroke of the non-designated piston of the master cylinder 1 the flow velocity entrains any gas bubbles or bubbles fill the entire channel cross-section by virtue of their surface tension.

The inner diameter of the return line 7 is therefore to be chosen so that it is dimensioned sufficiently small, so that the fluid flow of the hydrostatic medium substantially can not flow past gas bubbles, but this entrains.

An inner diameter of four millimeters is well suited, air bubbles in a hydrostatic actuator system against gravity to the liquid reservoir 10 to be carried along and thus removed from the hydrostatic system.

Controlling the flow direction in the flow line 6 and the return line 7 It is useful with classic check valves. At their tightness in the reverse direction are no extreme requirements and their arrangement along the respective wiring harness is arbitrary.

It seems expedient, the closing body of the check valves 11.1 . 11.2 In rest position already easy to put on the sealing seat, so they do not have to be closed by flowing pressure medium.

The first check valve 11.1 and / or the second check valve 11.2 can be biased to an advantageous manner by means of a spring (not shown) with a slight spring force. When the arrangement of the valves is stationary, the closing body (not shown) of the arranged in the flow line first check valve 11.1 be made of a material with a higher density than the fluid (eg metal), the closing body (not shown) in the return line 7 arranged second check valve 11.2 but with lower density than the fluid. The closing body can be made of a selected plastic of low density and / or as a hollow body and thus in the hydraulic fluid (the fluid or hydraulic medium) floating and thus closing the sealing seat in peace.

This is the closing body of the check valves 11.1 and 11.2 even at rest easily at the sealing seat and need not be closed by the hydrostatic medium by the flow alone.

A first line area 12.1 that is attached to the master cylinder 1 connects and a second line area 12.2 who is attached to the slave cylinder 1 are connected here are designed as a common line, so that the hydraulic distance between these two line areas 12.1 . 12.2 into the master cylinder 1 to the slave cylinder 2 leading supply line 6 and the slave cylinder 2 to the master cylinder 1 leading return line 7 divides.

The simply executed pipe sections 12.1 . 12.2 , attached to the master cylinder 1 and to the slave cylinder 2 be short enough so that the fluid exchange through the regular operational master piston stroke is certainly sufficient to flush gas pockets out of this critical passage. Appropriately, these line areas 12.1 . 12.2 arranged with slight incline.

With the solution according to the invention, it is possible to realize an automatic venting of a hydrostatic actuator system even when the slave cylinder 2 is arranged higher than the master cylinder 1 ,

LIST OF REFERENCE NUMBERS

1

 Master cylinder

2

 slave cylinder

3

 fluid line

4

 pedal device

5

 clutch

6

 supply line

7

 Return line

8th

 reservoir

9

 sniffing hole

10

 liquid reservoir

11.1

 first check valve

11.2

 second check valve

12.1

 first line area

12.2

 second line area

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102013203593 A1 [0005]

Claims (10)

Hydrostatic actuator system, in particular for actuating a clutch of a motor vehicle, with a master cylinder ( 1 ), as well as with a through the master cylinder ( 1 ) via a hydraulic line operable slave cylinder ( 2 ), characterized in that the master cylinder ( 1 ) at the same or a lower height level than the slave cylinder ( 2 ) and that the hydraulic distance between the master cylinder ( 1 ) and the slave cylinder ( 2 ) at least partially comprises two lines which serve as a flow line ( 6 ) and as a return line ( 7 ) are formed. Hydrostatic actuator system according to claim 1, characterized in that the master cylinder is arranged in an oil sump in a transmission housing. Hydrostatic actuator system according to claim 1 or 2, characterized in that the flow line ( 6 ) and the return line ( 7 ) of the hydraulic path parallel to each other and from the master cylinder ( 1 ) to the higher arranged slave cylinder ( 2 ) extend in at least a portion from bottom to top. Hydrostatic actuator system according to claim 2 or 3, characterized in that the flow line ( 6 ) and the return line ( 7 ) of the hydraulic section extend at least partially substantially vertically on the section extending from the bottom to the top. Hydrostatic actuator system according to one of claims 2 to 4, characterized in that in the flow line ( 6 ) a first check valve ( 11.1 ) and in the return line ( 7 ) a second check valve ( 11.2 ) is arranged. Hydrostatic actuator system according to one of claims 2 to 5, characterized in that the return line ( 7 ) is formed sufficiently small in the inner diameter such that gas bubbles are taken from the liquid flow. Hydrostatic actuator system according to one of claims 2 to 6, characterized in that the inner diameter of the return line ( 7 ) ≤ 4 millimeters. Hydrostatic actuator system according to one of claims 1 to 7, characterized in that on the master cylinder ( 1 ) a first line area ( 12.1 ) as a common fluid line ( 3 ) is formed, which towards the slave cylinder ( 2 ) in flow line ( 6 ) and return line ( 7 ). Hydrostatic actuator system according to one of claims 1 to 7, characterized in that the slave cylinder ( 2 ) a second line area ( 12.2 ) is designed as a common fluid line, which in the direction of the master cylinder in flow line ( 6 ) and return line ( 7 ). Hydrostatic actuator system according to one of claims 1 to 9, characterized in that the first check valve ( 11.1 ) and / or the second check valve ( 11.2 ) has / have a closing body, which in a rest position against a sealing seat of the check valve ( 11.1 / 11.2 ).

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