DE102009050848A1 - Device for releasing hydraulic oil of switching cylinder for releasing start-stop function of automatic transmission of internal combustion engine of passenger car, has fluid whose flow resistance is changed till gap or opening is blocked - Google Patents

Abstract

The device has a locking device (7) formed by a piston-cylinder arrangement (8) with a cylinder housing (9), and a working piston (10) for dividing the housing into two working chambers (11, 12). An electro-rheological or magneto-rheological valve (14) is arranged at a circumference (13) of the piston or in the piston as a gap (15) or an opening between the chambers. Variable magnetic or electric field is applied at the valve for changing flow resistance of electro-rheological or magneto-rheological fluid (16) in the chambers till the gap or the opening is blocked.

Description

The invention relates to a device for pulse-like releasing a vorratbaren in a storage enclosure fluid quantity, in particular for realizing a start-stop function in automatic transmissions, with a support against a first energy storage piston which is movable within the storage housing, with the storage housing limits the recordable amount of fluid , and actuated by means of an actuating device and released by a locking device, the fluid quantity impulsively ausschiebt from the storage housing, wherein the locking device holds the piston in its biased position and actuated by the actuating device, releasing the piston in a release position.

In modern motor vehicles, the internal combustion engine is switched off for reasons of saving fuel and minimizing pollutant emissions in suitable operating states. In order to enable the driving operation despite such a so-called. Engine start-stop function, a short starting operation of the internal combustion engine and an immediate adhesion in a driving gear of the vehicle is required.

In known automatic transmissions of motor vehicles or, for example, in automated manual transmissions, which are designed with wet-running multi-plate clutches, the clutches are supplied via a fluid supply device only when the internal combustion engine sufficient with hydraulic fluid. When Kraftschlussaufbau in such a transmission, a clutch play is first overcome and close the clutch or clutches by raising the fluid pressure completely. The clearance compensation of a clutch and their connections in the power flow is achieved by passing a quantity of fluid into a piston chamber of the hydraulically controllable and zuzuschaltenden clutches, wherein the amount of fluid is provided by the fluid supply device. In a restart of the motor vehicle after switching off the internal combustion engine may then be a plurality of switching elements in a transmission to open and close, whereby an unacceptably long time interval elapses until a complete adhesion in the transmission is made.

This disadvantage is counteracted in known transmissions with an electric motor driven hydraulic pump, whose delivery volume is independent of the speed of the internal combustion engine and which generates at least a pressure in the absence of pressure supply via the transmission main pump in the hydraulic system, by means of which the clutch play can be compensated. However, the electric motor drivable hydraulic pump leads to a deterioration of the transmission efficiency and the cost of the gearbox. In addition, it requires a considerable additional space requirement in the motor vehicle and a design effort for connection to the hydraulic system of the transmission and to an electrical control and regulation system.

The DE 10 2006 014 756 A1 shows and describes a device for storing and pulse-releasing a fluid amount of hydraulic fluid for a transmission device of a vehicle, with one of a storage housing and a movable, limited piston formed as a reservoir storage space, which is engageable with the transmission means for exchanging the fluid amount in operative connection. The piston is arranged movable within the storage space and controlled by an actuating device. The piston is also held by a locking device in its biased position. For this purpose, the locking means on locking means which hold the piston in its against a pressure spring formed as a first energy storage in a biased position. The locking device can be brought by the actuating device in a release position for the piston, wherein the amount of fluid in this case pulse-like manner in the transmission device, which is designed in particular as an automatic transmission is introduced.

With such devices can be basically defined to the needs of a particular consumer adapted fluid quantities to represent a practical engine start-stop function for automatic transmission provide. The known devices build at least consuming or require not inconsiderable space requirements.

In addition, the locking devices and the actuators of such devices are often unnecessarily complex because their number of parts is not minimized with respect to the representation of the necessary functions.

Based on this prior art, the present invention seeks to provide an apparatus for pulse-like releasing a vorratbaren in a storage enclosure fluid quantity, in particular for realizing a start-stop function in automatic transmissions, which is not only reliable and has a low space requirement, but the easy to manufacture and is particularly robust and low-wear.

This object is achieved with a device having the features of claim 1 in its entirety.

In particular, the device according to the invention has a locking device and an actuating device which does not require any mechanical parts to be engaged in the sense of locking or unlocking, namely in that the locking device for the piston is formed by a piston-cylinder arrangement with a cylinder housing , which is divided by a working piston in a first working chamber and in a second working chamber, wherein at the periphery of the working piston or in the working piston itself an electrorheological or magnetorheological valve is provided in the form of a passage gap or an opening between the working chambers. An actuating device is designed such that the gap or the opening between the working chambers is acted upon by an electric or magnetic field variable in its field strength, whereby the flow resistance of the electrorheological or magnetorheological fluid in the working chambers can be changed until the gap or opening becomes blocked is.

The fluid flow is thereby controlled by the magnetic field in the gap or in the opening on the working piston. Thus, a device is provided which is controlled solely by a change in the magnetic field and comprises only a few parts in total.

The device is thus easy to set up and is maintenance-free and insensitive in operation. With the device according to the invention also continuously variable volume of hydraulic fluid can be fed into a hydraulic system in the context of the total storable amount of fluid, in which the flow resistance in the gap or the opening is interactively changed.

In a particularly preferred embodiment of the device, the working piston of the locking device is fixedly connected to the storage housing, wherein the cylinder housing for the working piston is formed by a rear, projecting from the piston crown shaft. The shaft protrudes centrally axially from the piston. In one embodiment of the invention, the two working chambers are arranged radially between the shaft of the piston and the storage housing.

In another embodiment, the first and the second working chamber may also be arranged radially between the shaft and the working piston, wherein the working piston is formed in the manner of a cylinder with a radially circumferentially arranged bead or with a ring.

An electromagnetic coil for generating an electromagnetic field may be arranged in the working piston or fixed to a housing-fixed carrier, which projects into the shaft of the piston. In this way, the space requirement of the device can be minimized in an advantageous manner. However, if the space requirement of the device is not an essential determining variable, it may be expedient to arrange the coil on the outside of the storage housing or at a radial distance on the outside of the shaft of the piston.

In an easy-to-manufacture variant of the device, the shaft of the piston is formed as a hollow cylinder and the storage housing at least in the travel range of the piston designed as a cylinder by the piston with the shaft between a first end position and a second end position is arranged to be longitudinally displaceable. The shaft is preferably integrally formed with the piston and chosen in its position such that it is in an axial position, with an end cap of the storage housing in a, a maximum of the volume of the recordable amount of fluid defining position. It is expedient to effect the ejection of the stored amount of fluid in the storage housing by a spring means. The spring device can in principle be a tension or compression spring or working gas in a storage space. Other types of spring devices as energy storage, such as disc springs od. Like., Are also used.

The recordable amount of fluid in the storage housing corresponds to at least one filling volume of a hydraulic consumer, such as a shift cylinder on an automatic transmission of a passenger car. The device can be arranged as a separate unit to a drive gear or in a hydraulic control unit of the drive gear. The actuating device with the electro-or magnetorheological valve is deactivated, for example after an engine stop during a request to start the internal combustion engine of the motor vehicle, d. H. the electrotheological fluid or the magnetorheological fluid in the two working chambers is not exposed to a magnetic field, whereby the fluid of the working piston, for example, under the action of the pressure force of the first energy storage on the piston, the gap or the opening between the working chambers and the cylinder can overcome quickly. The pulse-like release of the amount of fluid from the storage space of the storage housing can also be made instead of a request for starting the internal combustion engine by releasing the service brake of the motor vehicle.

The invention is explained in more detail with reference to the embodiments illustrated in the drawings. Show it:

1 a longitudinal section through a device according to the invention in the filled state;

2 a longitudinal section through the device according to the 1 in the deflated state;

3 a schematic longitudinal section through a device with an electrorheological locking device with permanent magnet;

4 a schematic longitudinal section through a device and arranged in a piston shaft electromagnetic coil;

5 a schematic longitudinal section through a further device of a further magnetorheological locking device and an electromagnetic coil disposed on the outside of the housing of the device; and

6 to 8th in each case a schematic longitudinal section through further embodiments of the device solution according to the invention.

In the 1 is a device in a longitudinal section 1 to pulse-like release one in a storage enclosure 2 storable amount of fluid 3 shown. The device 1 is used to store a working fluid for a consumer of a hydraulic system (not shown), such as for storing and pulse-like delivery of hydraulic oil for a shift cylinder of an automatic transmission of a passenger car. The cylindrical storage enclosure 2 has a first energy storage 4 on, which is designed as a cylindrical compression spring. The energy storage 4 serves to pressurize a piston 5 with a compressive force sufficient to the piston 5 from his biased position, as in the 1 shown in a position where the amount of fluid 3 from the storage enclosure 2 has been expelled to proceed (cf. 2 ). The amount of fluid 3 is in the in 1 shown position of the piston 5 by a per se known fluid delivery device, such as a rotary pump, in the storage housing 2 introduced under pressure. The piston 5 is after the filling by a locking device 7 held in the shown, preloaded position.

The locking device 7 is from a piston-cylinder arrangement 8th educated. To the piston-cylinder arrangement 8th belongs in the in 1 embodiment shown a fixed to the storage enclosure 2 connected working piston 10 , The working piston 10 is as a substantially cylindrical sleeve with a at its periphery 13 annular elevation 26 arranged, approximately in half, axial length, formed. Above the working piston 10 is a cylinder housing 9 arranged by a shaft 17 on the piston 5 is formed. The working piston 10 has an outer diameter D _a , that of the inner diameter D _{i of} the shaft 17 in a stuffing box area S, plus a tolerance measure. The annular extension 26 is, a split 15 forming, to the cylinder housing 9 spaced and forms a certain separation between a first working chamber 11 and a kind of second working chamber 12 between the working piston 10 and the cylinder housing 9 out. The gap 15 is designed as an annular gap. The extension 26 forms with the gap 15 a valve 14 for one in the two working chambers 11 . 12 filled electro-rheological fluid 16 , Inside the working piston 10 is from one, the piston 5 opposite end one to beyond the extension 26 protruding electromagnetic coil 18 arranged, the voltage supply through an axial opening 27 in one, the storage enclosure 2 end closing lid 28 he follows.

Depending on the energization of the coil 18 and the electromagnetic field, the viscosity of the electrorheological fluid changes, so that, as in 1 shown the gap 15 from the fluid 16 filled, first working chamber 11 not in the direction of the second working chamber 12 can be overflowed. The first working chamber 11 extending axially from a gland forming the gland area S. 29 until the enlargement 26 on the working piston 10 extends completely with the electrorheological fluid 16 filled, with tensile forces from the sealing device 29 over the shaft 17 to the piston 5 be transferred to the piston 5 to hold in his position.

The locking device is formed in this way by the piston-cylinder assembly and the electrorheological fluid. The sink 18 forms together with a controlling this and supplying electrical voltage control unit, the actuator 6 out.

In 2 is the device 1 in an energized state of the coil 18 shown, wherein the electrorheological fluid 16 from the first working chamber 11 to the second working chamber 12 has flowed and thereby the electrorheological valve 14 overflowed. The piston 5 is characterized by the first energy storage 4 acted upon in a position that a minimum of the fluid quantity 3 in the storage enclosure 2 corresponds and the amount of fluid 3 is delivered to a consumer of an automatic transmission.

The amount of fluid 3 is thereby by a cover 30 completed on the outside, the pot-shaped in its basic configuration is formed, and with the storage housing formed as a steel cylinder 2 via an end to the storage enclosure 2 provided fine thread 31 screwed as well as an interposed sealing element 32 sealed accordingly. As another element of the storage enclosure 2 is a disc-like lid 33 with an end wall portion of the storage enclosure 2 crimped. On the flanged lid 33 , which has a slightly larger passage opening for the amount of fluid 3 has as the lid 30 , lies the lid 30 on. A flange plate 34 for attaching the device 1 on an automatic transmission extends over an axial partial length of the storage housing 2 from the lid 30 leading away.

The lid 30 opposite lid 28 on the storage enclosure 2 is the same as the disc-like lid 30 with an end wall portion of the storage enclosure 2 crimps, wherein a sealing element 35 interposed. The lid 28 has a recording 36 on in the nature of a stepped bore with increasing diameter towards the housing interior, wherein the working piston 10 is centered. The working piston 10 protrudes from the inside to the outside through the recording 36 through and is with a threaded portion and a nut thereon 37 on the lid 28 screwed. The working piston 10 forms with his, the piston 5 facing end of an axial stop for the piston 5 (see. 1 ) out.

The shaft 17 of the piston 5 points from the piston 5 starting about in its half length on a jump in its wall thickness, which from about half its length to less than half compared to the wall thickness of his from the piston 5 outgoing section is. By this constructive measure is the piston 5 , the shaft 17 and the cylinder housing 9 the piston-cylinder arrangement 8th integrally formed and mounted with the other components of the device 1 , Thereby - in particular the electrorheological valve 14 finished with tight tolerances. The piston 5 is sealed in a conventional manner with inserted in circumferential grooves sealing or piston rings.

As far as for the embodiments described below, the same reference numerals as for the embodiment described above according to the 1 and 2 are used, the previous versions also apply to the extent explained below components of other embodiments.

In 3 is a schematic representation of another embodiment of the device 1 for the pulse-like release of a fluid amount 3 shown, the storage enclosure 2 as a cylinder 22 is shown. The locking device 7 is from a housing-fixed working piston 10 forming, annular extension 26 the wall of the cylinder 22 formed, wherein seen in cross-section rectangular extension 26 at about half the length of the storage enclosure 2 is arranged.

The piston 5 is in its, a minimum of the volume of fluid 3 in the storage enclosure 2 engaging position shown. The piston 5 is integral with the cylinder housing 9 the locking device 7 partially representing shaft 17 educated. On the piston 5 then the shaft 17 reduced in diameter relative to the diameter of the piston 5 educated. The shaft 17 points to his, the piston 5 opposite free end an annular extension 38 with approximately the same diameter as the diameter of the piston 5 , Axial between this extension 38 and the piston 5 spans from the extension 26 of the cylinder 22 largely separated the first and the second working chamber 11 . 12 on.

The extension 26 forms to the shaft 17 of the piston 5 an annular gap 15 out, in turn, the electrorheological valve 14 for electrorheological fluid 16 in the two working chambers 11 . 12 forms. The piston 5 and the extension 38 on the shaft 17 are with inserted in grooves sealing elements against the inner wall of the cylinder 22 sealed.

On a plunger-like, in the shaft 17 axially displaceable carrier 19 are permanent magnets 39 set in the area of the electrorheological valve 14 are arranged axially displaceable. For this purpose, the carrier 19 with an anchor of a magnet system 40 operatively connected. Under the effect of the magnetic field of the permanent magnets 39 is the valve 14 locking and the piston 5 remains in its respective assumed position. The in 3 shown piston 5 is through a working gas 25 in a shank-side workspace 24 pressed in the position shown and can when moving the permanent magnet 39 be biased in the solid line position by hydraulic fluid through the opening 27 is pressed. Subsequently, the permanent magnets 39 back into the area of the valve 14 be driven. The piston 5 can hold its occupied, pre-stressed position. The electrorheological fluid 16 can no longer flow from one working chamber to the other working chamber.

In the 4 is a schematic longitudinal section of another embodiment of a device 1 to pulse-like release one in the storage enclosure 2 stocked amount of fluid 3 shown, the storage enclosure 2 , The piston 5 with shank 17 , as well as the working piston 10 and this one associated first and second working chambers 11 . 12 identical, as in the 3 shown, are constructed. The carrier 19 is unlike the one in the 3 shown embodiment fixed to the housing and serves for the fixed positioning of an electromagnetic coil 18 and temporarily providing a magnetic field to the valve 14 , The carrier 19 also has a possibility for cable bushing for the electromagnetic coil 18 on and for introducing working gas 25 in the, the storable amount of fluid 3 rearward space from the piston 5 is limited.

The device 1 , which in a schematic longitudinal section in 5 is shown differs by the electromagnetic coil 18 on the outside 20 of the cylinder 22 that the storage case 2 essentially forms, is arranged. This results in a simplified installation and maintenance.

The 6 shows in a further schematic longitudinal section through a device 1 the working piston 10 the locking device 7 in a tight with the piston 5 connected way. The working piston 10 is formed in the manner of a cylindrical plunger with an extension 26 at its periphery, radially to form the gap 15 to the inner circumference of the cylinder housing 9 the piston-cylinder arrangement 8th protrudes. The cylinder housing 9 is on the lid 28 , the piston 5 turned away in the position shown, and fixed by a cylinder cover 41 at its free, in the storage enclosure 2 limited end. The cylinder cover 41 is from the working piston 10 penetrates sealingly. Around the entire circumference of the cylinder housing 9 around is an electromagnetic coil 18 arranged with a radial gap whose magnetic field is the electrorheological valve 14 closes or opens.

The piston 5 is on his piston back with a working gas 25 biased. In the 6 revealed device 1 has few moving parts and can therefore build up very compact.

In the 7 is a further embodiment of the device 1 shown in a schematic longitudinal section. The working piston 10 is as an extension 26 one the storage enclosure 2 towering, cylindrical traverse 42 arranged and so far as possible. The traverse 42 also penetrates the piston 5 and is in the lid 28 . 30 of the storage enclosure axially centered. The shaft 17 of the piston 5 forms the cylinder housing 9 for the piston-cylinder arrangement 8th from and has about half the outer diameter as that of the piston 5 , At his, the piston 5 remote from the free end, the cylinder housing 9 a sealing device 29 on. With the sealing device 29 designed in the manner of a stuffing box or labyrinth seal slides the cylinder housing 9 at the crossbar 42 along. Inside the cylinder housing 9 shares the extension 26 the two workrooms 11 . 12 for the electrorheological fluid 16 on. An electromagnetic coil 18 is on vehicle-mounted girders 19 parallel to the wall of the cylinder 22 of the storage enclosure 2 into the interior of the storage enclosure 2 protrude, held. The sink 18 is in the axial region of the electrorheological valve 14 on the outside 21 held the shaft at a radial distance a.

In the in 7 shown position of the piston 5 is the coil 18 in de-energized state and the piston 5 is under the action of as a helical compression spring 23 formed first energy storage 4 in his, a minimum of the stored amount of fluid 3 proceed to the appropriate position. Unless the coil 18 is formed so that it over the entire length of the shaft 17 enough, this can also be on the outside 20 of the shaft 17 set and together with the piston 5 method (cf. 8th ). At the same time, the arrangement of carriers is unnecessary 19 for the coil, as is the embodiment in 7 shows. The sink 18 is to be supplied with a flexible supply cable in the storage enclosure with power.

QUOTES INCLUDE IN THE DESCRIPTION

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Cited patent literature

• DE 102006014756 A1 [0005]

Claims (12)

Device for the pulse-like release of a in a storage housing ( 2 ) storable amount of fluid ( 3 ), in particular for realizing a start-stop function in automatic transmissions, with a counter to a first energy store ( 9 ) supporting piston ( 5 ) located inside the storage enclosure ( 2 ) movable with this the recordable amount of fluid ( 3 ) and by means of an actuator ( 6 ) and by a locking device ( 7 ), the amount of fluid ( 3 ) impulsively from the storage enclosure ( 2 ), wherein the locking device ( 7 ) the piston ( 5 ) in its pre-stressed position and that of the actuating device ( 6 ) actuates in a release position the piston ( 5 ), characterized in that the locking device ( 7 ) by a piston-cylinder arrangement ( 8th ) with a cylinder housing ( 9 ) formed by a working piston ( 10 ) into a first working chamber ( 11 ) and into a second working chamber ( 12 ), that at the periphery ( 13 ) of the working piston ( 10 ) or in the working piston ( 10 ) itself an electrorheological or magnetorheological valve ( 14 ) as a gap ( 15 ) or opening between the working chambers ( 11 . 12 ), the one with the, the actuating device ( 6 ) is applied variable magnetic or electric field, and that the flow resistance of the in the working chambers ( 11 . 12 ) located electrorheological or magnetorheological fluid ( 16 ) up to a blockage of the gap ( 15 ) or the opening is changeable. Apparatus according to claim 1, characterized in that the working piston ( 10 ) fixed to the storage enclosure ( 2 ) and that as a cylinder housing ( 9 ) a shaft ( 17 ) of the piston ( 5 ) centrally disposed axially of the piston ( 5 ). Apparatus according to claim 1 or 2, characterized in that the first and the second working chamber ( 11 . 12 ) between the shaft ( 17 ) and the storage enclosure ( 2 ) are arranged. Apparatus according to claim 1 or 2, characterized in that the first and the second working chamber ( 11 . 12 ) between the shaft ( 17 ) and the working piston ( 10 ) are arranged. Device according to one of claims 1 to 4, characterized in that an electromagnetic coil ( 18 ) for generating an electromagnetic field in the working piston ( 10 ) is arranged. Device according to one of claims 1 to 4, characterized in that the electromagnetic coil ( 18 ) at one in the shaft ( 17 ) of the piston ( 5 ) projecting or movable support ( 19 ) is arranged. Device according to one of claims 1 to 4, characterized in that the electromagnetic coil ( 18 ) on the outside ( 20 ) of the storage enclosure ( 2 ) is arranged. Device according to one of claims 1 to 4, characterized in that the electromagnetic coil ( 18 ) at a radial distance (a) on the outside ( 21 ) of the shaft ( 17 ) is arranged. Device according to one of claims 1 to 8, characterized in that the shaft ( 17 ) is formed as a hollow cylinder and that the storage housing ( 2 ) at least partially as a cylinder ( 22 ) is formed, in which the piston ( 5 ) with the shaft ( 17 ) is arranged longitudinally displaceable between a first end position and a second end position. Device according to one of claims 1 to 9, characterized in that the shaft ( 17 ) in one piece with the piston ( 5 ) is trained. Device according to one of claims 2 to 10, characterized in that the shaft ( 17 ) in a maximum of the amount of fluid ( 3 ) of the storage enclosure ( 2 ) defining position in axial abutment with the storage housing ( 2 ). Device according to one of claims 1 to 11, characterized in that the first energy store ( 24 ) as a compression spring ( 23 ) or workspace ( 24 ) with a working gas ( 25 ) is trained.

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