Multi-position cylinder

Abstract

A multi-position cylinder comprises: a fluidic actuator (100) having a shift rod (115); a first bearing (210) for the shift rod (115); a second bearing (220) for the shift rod (115); a shift element (300) which is fastened to the shift rod (100) between the first bearing (210) and the second bearing (220). The fluidic actuator (100) is designed to axially move the shift rod (115), together with the shift element (300), between a plurality of positions (P1, P2, P3).

Description

[0001] DESCRIPTION

[0002] Multi-position cylinder

[0003] The present invention relates to a multi-position cylinder and in particular to a cylinder in a housing with a double bearing.

[0004] Conventional transmissions, especially gearshifts for trucks, often require a large number of gears to be shifted. Accordingly, the shift rods are arranged so they can be moved axially over long distances. Conventional transmissions repeatedly result in high levels of wear and leaks in fluid actuators (hydraulic or pneumatic), as the shifting events require high forces over long distances. Due to the long shift rods, high leverage forces can occur, which often lead to leaks in the actuators.

[0005] Therefore, there is a need for additional fluidic actuators or multi-position cylinders that allow safe switching of multiple positions while at the same time not endangering the tightness of the fluidic actuator - even during long operation.

[0006] At least some of the above-mentioned problems are solved by a multi-position cylinder according to claim 1. The dependent claims relate to further advantageous developments of the subject matter according to the main claim.

[0007] The present invention relates to a multi-position cylinder comprising: a fluidic actuator with a shift rod; a first bearing for the shift rod; a second bearing for the shift rod; and a shifting element fastened to the shift rod between the first bearing and the second bearing. The fluidic actuator is designed to axially move the shift rod, together with the shifting element, between a plurality of positions. Optionally, the fluidic actuator comprises at least one piston and a piston housing. The at least one piston can separate a first pressure chamber from a second pressure chamber in the piston housing, and the shift rod can be fastened to the at least one piston so as to be movable between the plurality of positions in a pressure-controlled manner. The fluidic actuator can thus switch at least two positions in a pressure-controlled manner.

[0008] Optionally, the first bearing is provided in the piston housing in a through opening of the piston housing.

[0009] Optionally, the fluidic actuator includes only one sealed opening through which the shift rod extends and through which no fluid flow occurs. However, additional openings can be provided to ensure fluid supply and removal.

[0010] Optionally, the multi-position cylinder includes a bracket that holds both the primary and secondary bearings together. Both the primary and secondary bearings provide secure axial guidance for the shift rod. This prevents the shift rod from tilting, as is the case with a cantilever.

[0011] Optionally, the holder comprises a position stop with an integrated position sensor (e.g. at a predetermined position). The position sensor can be used to record the current position of the piston or to detect the stop at the position stop. The piston can optionally have a piston stop at a predetermined axial position. A first sliding piston and a second sliding piston can be arranged axially displaceably between the piston housing and the piston such that the position stop and the piston stop are located between the first sliding piston and the second sliding piston. At a predetermined pressure ratio between the first pressure chamber and the second pressure chamber, the piston moves until the piston stop is located at the position stop, thereby reaching an intermediate position. This movement is caused by the sliding pistons, as they are subject to the pressure forces.Optionally, the multi-position cylinder can switch the switching element to three stable positions: a first position where only the first pressure chamber is depressurized, a second position where only the second pressure chamber is depressurized, and a third position where neither pressure chamber is depressurized, with the third position being the intermediate position. The first pressure chamber and the second pressure chamber can have different effective areas for the actuator fluid with respect to the piston and the sliding piston, so that the predetermined pressure ratio for the intermediate position can be adjusted via the different effective areas.

[0012] It goes without saying that the same technical effect can be achieved even if the pressure difference between the first pressure chamber and the second pressure chamber is chosen to be sufficiently large. It is not absolutely necessary for a chamber to be pressure-free to achieve the displacement of the piston to one of its end positions. Nevertheless, it remains true that the displacement can be achieved even when pressure is free.

[0013] Optionally, the piston together with the sliding pistons defines a symmetrical piston arrangement (e.g. mirror-symmetrical for a mirror plane perpendicular to the axial direction).

[0014] Embodiments also relate to a gear actuator with a multi-position cylinder as previously described.

[0015] Further embodiments relate to a commercial vehicle, in particular a truck, with a transmission actuator as described above.

[0016] Embodiments solve the problems mentioned above by coupling a multi-position cylinder for a fluidic actuator to a switching rod that is displaceably mounted at two bearing points, and at least one switching element is arranged between the bearing points and is only moved in the intermediate space. Both bearing points are accommodated, in particular, by one component. The component can be, for example, a holder or part of a housing (e.g., a cover), as long as it can ensure sufficient mechanical stability. In particular, embodiments utilize different active surfaces when actuating the fluidic actuator in one or the other direction.

[0017] The multi-position cylinder can comprise a housing in which both the first bearing and the second bearing are located or held thereby. The aforementioned support can be part of the housing. This offers the advantage of achieving maximum concentricity of both bearings and high strength.

[0018] Advantageously, the multi-position cylinder has only one opening to be sealed, between the fluid chambers of the multi-position cylinder and to the outside. The shift rod can be guided through the one opening to be sealed. The multi-position cylinder is, in particular, a three-position cylinder that has two axial end positions and, between them, an intermediate or central position, which is assumed at a predetermined pressure ratio between the two chambers of the fluidic actuator. In particular, embodiments are characterized in that the piston arrangement has a symmetrical shape along the axial direction.

[0019] The embodiments of the present invention will be better understood from the following detailed description and the accompanying drawings of the various embodiments, which, however, should not be construed as limiting the disclosure to the specific embodiments, but are for explanation and understanding only.

[0020] Fig. 1 shows a multi-position cylinder according to an embodiment of the present invention.

[0021] Fig. 1 shows a multi-position cylinder according to an embodiment of the present invention. The multi-position cylinder comprises a fluidic actuator 100 (i.e., not an electric motor actuator) having a piston 150 to which a shift rod 115 is attached. A shift element 300, such as a shift fork, which carries out the shifting operations, is attached to the shift rod 115. In addition, the multi-position cylinder comprises a first bearing 210 for the shift rod 115 and a second bearing 220 for the shift rod 115, wherein both bearings 210, 220 allow an axial displacement of the shift rod 115, but fix the shift rod 115 radially. According to embodiments, the shift element 300 is attached to the shift rod 115 between the first bearing 210 and the second bearing 220, such that axial displacements of the shift rod 115 lead to an axial displacement of the shift element 300.

[0022] The multi-position cylinder further includes a mount 400 for the fluidic actuator 100, with both the first bearing 210 and the second bearing 220 being jointly held by the mount. In this way, the first bearing 210 and the second bearing 220 provide secure axial guidance for the shift rod 115. The mount 400 can be any unitary component (e.g., a housing part or a cover) as long as it can provide the desired stability. It should not be an assembly of multiple components.

[0023] The fluidic actuator 100 comprises at least one piston 150 (it may also be a plurality of coupled pistons) and a piston housing 160. The piston 150 separates a first pressure chamber 110 from a second pressure chamber 120 in the piston housing 160 and is linearly movable between a first stop 161 and a second stop 162. The distance between the stops 161, 162 defines the maximum achievable displacement. If the first pressure chamber 110 is pressure-free or has little pressure and the second pressure chamber 120 has a minimum pressure (is filled), the piston 150 moves to the first stop 161. On the other hand, if the second pressure chamber 120 is pressure-free (or has only a low pressure) and the first pressure chamber 110 has a further minimum pressure, the piston 150 moves to the second stop 162. Accordingly, the switching element 300 is in the first position P1 or in the second position P2.The minimum pressure can be selected to ensure movement of the piston 150 in either direction in any case. It is understood that for the movement of the piston 150, it is not absolutely necessary for one of the two pressure chambers 110, 120 to be depressurized. In this case, however, the pressure difference between the pressure chambers 110, 120 must be sufficiently large.

[0024] The center position P3 can be assumed at a predetermined pressure ratio between the first pressure chamber 110 and the second pressure chamber 120. To switch to this position, the holder 400 comprises a position stop 405 with an integrated position sensor 406, and the piston 150 comprises a piston stop 152 at a predetermined axial position. Furthermore, a first sliding piston 130 and a second sliding piston 140 are arranged axially displaceably between the piston housing 160 and the piston 150 such that the position stop 405 with the integrated position sensor 406 and the piston stop 152 are both located between the first sliding piston 130 and the second sliding piston 140 and each provide a stop for the sliding pistons 130, 140. The sliding pistons 130, 140 can extend around the piston 150 and be arranged to slide on its cylindrical surface.Therefore, they also increase the effective area for the pressure in the first and second pressure chambers 110, 120 through the sliding pistons 130, 140. At a predetermined pressure ratio between the first pressure chamber 110 and the second pressure chamber 120, the piston 150 is guided to the position stop 405 with integrated position sensor 406 via the sliding pistons 130, 140, which strike the piston stop 152 and carry it along, whereby the intermediate position P3 is reached.

[0025] Thus, the housing stop with integrated position sensor 405, 406 (or the piston stop 152) defines the intermediate or center position P3, which is reached when the piston stop 152 is at the same axial position as the housing stop with integrated position sensor 405, 406. The intermediate position P3 can therefore also be freely selected between the end positions P1 and P2 (e.g., by appropriately displacing the housing stop 405 with integrated position sensor 406). In particular, the intermediate position P3 can be fixed centrally between the two end positions P1 and P2. Furthermore, the active surfaces in the first pressure chamber 110 and the second pressure chamber 120 can be selected such that the intermediate position P3 is assumed when the pressure in the first pressure chamber 110 and the second pressure chamber 120 is the same (e.g., by fluidly connecting both chambers).However, the predetermined pressure ratio for assuming the intermediate position P3 can be adjusted by changing the effective areas in the first pressure chamber 110 and / or in the second pressure chamber 120.

[0026] The switching element 300 can thus be switched between three switching positions: a first switching position P1, a second switching position P2 and a third switching position P3, wherein the third switching position P3 is the predetermined intermediate position.

[0027] The fluid actuator 100 is therefore controlled by a pressurized fluid (e.g., air or hydraulic oil), for which purpose additional fluid openings are provided to effect the inflow and outflow of the pressurized fluid. However, these openings are to be distinguished from opening 105, through which the switching rod 115 is guided. The fluid naturally flows through the fluid openings, whereas it is not intended to flow through opening 105.

[0028] One advantage of embodiments is that no additional sealed openings are required in the fluidic actuator 100. Furthermore, the two bearings 210, 220 provide high stability for the switching rod 115, which cannot tilt during axial displacements and thus protects the existing opening 105. This significantly increases the service life of the multi-position cylinder, since the one seal in the opening 105 is subjected to little or no load in one direction (e.g., perpendicular to the axial displacement).

[0029] The features of the invention disclosed in the description, the claims and the figure may be essential for the realization of the invention both individually and in any combination.

[0030] LIST OF REFERENCE SYMBOLS

[0031] 100 fluidic actuator (e.g. pneumatic)

[0032] 105 passage opening

[0033] 110 first pressure chamber

[0034] 115 shift rod

[0035] 120 second pressure chamber

[0036] 130 first sliding piston

[0037] 140 second sliding piston

[0038] 150 pistons

[0039] 152 piston stop

[0040] 160 piston housing

[0041] 210 first storage

[0042] 220 second storage

[0043] 300 switching element (e.g. shift fork)

[0044] 400 bracket

[0045] 405 Position stop

[0046] 406 integrated position sensor

[0047] P1, P2, P3 switching positions

Claims

PATENT CLAIMS 1 . Multi-position cylinder, characterized by - a fluidic actuator (100) with a switching rod (115); - a first bearing (210) for the shift rod (115); - a second bearing (220) for the shift rod (115); - a switching element (300) which is fastened to the switching rod (100) between the first bearing (210) and the second bearing (220), wherein the fluidic actuator (100) is designed to move the switching rod (115) together with the switching element (300) axially between a plurality of positions (P1, P2, P3).

2. Multi-position cylinder according to claim 1, characterized in that the fluidic actuator (100) has at least one piston (150) and a piston housing (160), wherein the at least one piston (150) in the piston housing (160) separates a first pressure chamber (110) from a second pressure chamber (120) and the switching rod (115) is fastened to the at least one piston (150) in order to be movable between the plurality of positions (P1, P2, P3) in a pressure-controlled manner.

3. Multi-position cylinder according to claim 2, characterized in that the piston housing (160) provides the first bearing (210) in a through opening (105).

4. Multi-position cylinder according to claim 3, characterized in that the fluidic actuator (100) has only one sealed opening (105) through which the switching rod (115) extends and through which no fluid flow occurs.

5. Multi-position cylinder according to one of the preceding claims, characterized by a housing (400) in which both the first bearing (210) and the second bearing (220) are located.

6. Multi-position cylinder according to one of the preceding claims, characterized by a holder (400) which holds both the first bearing (210) and the second bearing (220) together and the first bearing (210) and the second bearing (220) provide an axial guide for the switching rod (115).

7. Multi-position cylinder according to claim 6, characterized in that - the holder (400) has a position stop (405) with an integrated position sensor (406), - the piston (150) has a piston stop (152) at a predetermined axial position, and - a first sliding piston (130) and a second sliding piston (140) are arranged between the piston housing (160) and the piston (150) in an axially displaceable manner such that the position stop (405) and the piston stop (152) are located between the first sliding piston (130) and the second sliding piston (140), so that at a predetermined pressure ratio between the first pressure chamber (110) and the second pressure chamber (120), the piston stop (152) is located at the position stop (405), thereby defining an intermediate position (P3).

8. Multi-position cylinder according to claim 7, which allows three stable positions for the switching element (300): a first position (P1) where only the first pressure chamber (110) is pressure-free, a second position (P2) where only the second pressure chamber (120) is pressure-free, a third position (P3) where none of the pressure chambers (110, 120) is pressure-free, wherein the third position (P3) is the intermediate position, characterized in that the first chamber (110) and the second chamber (120) for the actuator fluid have the same or different effective areas on the piston (150) and the sliding piston (130, 140), so that a predetermined pressure ratio for the intermediate position (P3) is set over different different effective areas.

9. Multi-position cylinder according to claim 7 or claim 8, characterized in that the piston (150) together with the sliding pistons (130, 140) define a symmetrical piston arrangement.

10. A transmission actuator characterized by a multi-position cylinder according to one of claims 1 to 9.

11. A commercial vehicle, in particular a truck, characterized by a transmission actuator according to claim 10.

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