WO2010134878A1

WO2010134878A1 - Electric switching device and method of manufacture

Info

Publication number: WO2010134878A1
Application number: PCT/SE2010/050537
Authority: WO
Inventors: Gunnar Janson
Original assignee: Nordhydraulic Ab; Hakaryd Ab
Priority date: 2009-05-18
Filing date: 2010-05-18
Publication date: 2010-11-25
Also published as: EP2433291A1; CN102484007A; EP2433291A4; SE0950346A1; SE537288C2; CN102484007B

Abstract

The present invention related to an electric switching device comprising a cover shaped casing (1), one or more in the casing (1) included actuation parts (34) belonging to the respective electric switching circuit (32) and a membrane (35) creating a part of the casing (1) and is arranged as a protecting cover placed at a location directly above every actuation part (34). During push-down, the membrane (35) is arranged to cooperate with the actuation part (34) so that electric connection is established or broken. The switching devices (32) can be arranged on a carrier (31), for example an electric circuit, which carrier (31) is detainingly carried by holding means (30) in the cover shaped casing (1) or in a frame (4) included in the casing (1). A method of manufacturing such an electric switching device is also provided.

Description

ELECTRIC SWITCHING DEVICE AND ITS METHOD OF MANUFACTURE

Technical field

[0001] The present invention relates generally to a switching device such as a push button with an integrated cover and a method of manufacturing such a switching device.

Background art

[0002] Switching devices such as push buttons or toggle switches of the kind to be integrated in cover shaped apparatus casings are well known and are used in a large number of applications, for instance control units for work vehicles, such as forest vehicles, tractors or the same. In order to let the driver or operator of such a vehicle work safely and efficiently, it is desirable that the electric switching devices, despite a low building height, can be operated and switched by the operator without having to take his eyes from an ongoing operation. With other words it is desirable that localization of the buttons can be done only by sensation of touch or tactility. Since the switching devices not infrequently are used in demanding and hostile work environments, the switches are required to be moisture proof so that water is prevented from entering into the sensitive electronics that is included in the housing or casing of the control unit. The demand on reliability has increased concurrently with the inclusion of more and more advanced electronics in the apparatus casings. A number of earlier proposed measures to create switching devices that both are moisture proof and durable and manages a great number of button pushes without failure have indeed proved to be working well, however there is always an aim to further improve them. With the expression "moisture proof" is meant that the switching devices at least can be operated with wet hands, that they are able to manage rain and that they can be washed with water.

RECORD COPY-TRANSLATION (Rule 12,4) Summary of invention

[0003] An object of the present invention is to create an electric switching device adapted to be integrated in a cover shaped apparatus casing which by push-down establishes or breaks electric contact with electronics arranged in the casing, whereby the switching device is created to manage the moisture proof demands so that water is prevented from entering into the electronics in the casing.

[0004] The mentioned objects of the invention are created with an electric switching device and a method for arranging such a switching device in a casing according to the independent patent claims.

[0005] The electric switching device comprises a cover shaped casing, one or more in the casing arranged actuation parts belonging to a respective switching device circuit and one membrane creating a part of the casing and which is arranged as a protecting cover placed at a location directly above every actuation part. During push-down, the membrane is arranged to cooperate with the actuation part so that electric connection in the switching device circuit is established or broken.

[0006] The electric switching device can be arranged on a carrier, for example an electric circuit, which is detainingly carried by holding means in the cover shaped casing or in a frame included in the casing. Further, the frame or the casing may comprise a guiding for every actuation part so that one actuation part belonging to each switching device circuit is located in a hole in a corresponding guiding in the frame.

[0007] By arranging interfaces on the outwards facing side of the membrane, which are sensible by a user's finger tip and which are separating the actuation part belong to each switching device circuit from each other, a person can with his finger tips distinguish each actuation part from the other. The guiding belonging to the respective actuation part has an enclosing upper edge which at least during push-down is supported by and cooperates with the underside of the membrane.

[0008] In one embodiment of the invention, the cover shaped casing comprises a combination of an elastic plastic material and a rigid plastic material and the membrane forms a part of the elastic plastic material.

[0009] The carrier is preferably fully or partly constituted of an electric circuit on which the electric circuit switching devices are arranged and electronically connected so that electrical contact is broken or established during a push-down of the actuation part belonging to each switching device circuit.

[0010] The holding means comprises, in one embodiment of the invention, grooves arranged in the cover or in the frame into which the carrier is insertable. Alternately, snap means is used into which the carrier can be snapped.

[001 1 ] The method is referring to manufacturing of an electric switching device with an integrated cover. The electric switching device comprises one or more in the casing included actuation parts belonging to a respective switching device circuit and a membrane arranged as a protecting cover over every actuation part. The method comprises the steps:

manufacturing of a casing whereby the membrane is created as a part of said casing and is provided with interfaces which are sensible by a user's finger tip,

providing a carrier onto which the electric switching circuit is directly arranged, arranging the carrier in a detaining way in the casing so that an actuation part belonging to each electric switching circuit is located at a location directly below the membrane.

[0012] During manufacturing, a polymer material is used and some plastic forming method, for example thermoplastic elastomeric material and some of the methods extrusion, blow moulding, injection moulding or a combination of these.

[0013] The idea behind the invention is the possibility to, for one specific area, form a part of a protective cover shaped casing, such as a protective membrane for the electric switch, in such a way that it is sensible by the driver's finger tips and manages repeated push-downs. A further idea behind the invention is also a chance to accomplish a moisture proof protection over the electrical parts of the control unit and to accomplish softness in the manipulation of the electric switches. The softness in manipulation makes it possible to create a direct action effect when it comes to contact establishment, this is certainly important in order to create a satisfactory tactile communication with the electric switch.

[0014] Embodiments of the present invention are described in the independent patent claims. Other purposes, advantages and novel features of the invention will be described in the detailed description of the invention, with reference to the accompanying drawings.

Brief description of drawings

[0015] The invention is now described, by way of example, with reference to the accompanying drawings, in which:

Fig. 1 discloses a perspective view of an electric switching device according to the invention integrated in a cover shaped casing according to the invention, Fig. 2 discloses α side view of the apparatus casing according to Fig. 1 , in a view directly from behind,

Fig. 3 discloses a perspective view of parts included in the inventive electric switching device enclosed in the apparatus casing in Fig. 3,

Fig. 4 discloses a schematic section view through a part of an electric switching device with a part of an electric circuit according to Fig. A₁

Fig. 5 discloses a schematic section view through a piece of a tactile membrane comprised in the electric switching device according to the invention,

Fig. 6-8 discloses perspective views of three different embodiments of the present arrangement integrated in an apparatus casing manufactured by extrusion, blow moulding and injection moulding.

Detailed description of preferred embodiments

[0016] The invention is described in an introductory part with reference to Fig. 1- Fig. 3, which schematically discloses embodiments of an electric switching device integrated in an apparatus casing for a control unit. After this introductory part other embodiments of the invention is disclosed where the electric switching device is integrated in a casing, but not necessarily for the same application.

[0017] In Fig. 1- Fig. 3 an apparatus casing 1 is disclosed which is outwardly limited by an opposing upper 2 and a lower cover shaped part 3 and a between said parts arranged frame 4. Said frame 4 is adapted to function both as a support between the two cover shaped parts 2, 3 and as a holder and carrier of electrical components. As best described in Fig. 2, push-button sets 10, 14 are grouped together as three and four electric switches or push-buttons at the upper cover shaped part 2. The cover shaped parts and the frame can be made of any plastic material, for example thermoplastic elastic material (TPE), but the invention is not limited to this. Also metals, composites and ceramic material can be used in one or more parts.

[0018] In Fig. 3, both the frame 4 and the upper and lower cover shaped parts 2, 3 are disclosed in more detail. As apparent from this, the frame comprises a framework that both detainingly carry electrical components and acts as a support against the upper cover shaped part 2. Thus, the frame 4 has been given a shape that in all essential details corresponds to the inside of both cover shaped parts 2, 3 and is therefore acting both carrying and supporting between these parts. In more detail the frame 4 comprises a cover shaped dome like basket part and a, in relation to this, horizontally sidewards directed mounting part.

[0019] In one embodiment according to the invention, the upper cover shaped part 2 is made of a material, preferably a plastic material, which is less resistant against bending than the material in the lower cover shaped part 3 as well as said frame 4. The upper cover shaped part 2 is made of any plastic material, such as a thermoplastic elastic material (TPE) for example polyeten or similar while the lower cover shaped part 3 is made of a stiffer material, such as for example a urethane plastic, which can be polyurethane. Also the frame 4 is preferably made of the said stiffer material. Each and one of the said cover shaped parts 2, 3 according to this embodiment can be manufactured by injection moulding.

[0020] Fig. 3 illustrates schematically an electric switching device adapted to create an integrated part of a cover shaped apparatus casing 1 according to the invention. The electric switching device comprises a frame 4 with one or more guiding 33, one in a hole in each guiding arranged actuation part 34 of an electric switching device circuit 32, one membrane 35 arranged as a protective cover over each actuation part 34, one carrier 31 arranged in the cover shaped apparatus casing 1 , on which carrier 31 the electric switching circuit 32 is arranged. The membrane 35 constitutes a part of the apparatus casing 1 and the carrier 31 is so detainingly carried in the apparatus casing that an actuation part 24 belonging to each electric switching circuit 32 is arranged in a corresponding guiding 33 by the frame 4 at a location direct below the membrane. Furthermore, on the outwards facing side of the membrane interfaces are arranged, which are sensible by a user's finger tip and which are separating the actuation part belonging to each switching device circuit from each other, in such a way that a person can with his finger tips distinguish each actuation part from the other. The guiding belonging to the respective actuation part has an enclosing upper edge which at least during pushdown is supported by and cooperates with the underside of the membrane.

[0021] In one embodiment, the actuation parts 34 are moveably controlled and arranged in each guidance 33. The device comprises holding means 30 by which the carrier 31 is so detainingly carried in the apparatus casing that one actuation part 34 belonging to each electric switching circuit is found under cooperation with the corresponding guidance 33 in the frame 4.

[0022] In one implementation of an electric switching device according to the invention, both the mounting part 24 and the basket part 20 can be provided with holding means 30 of a snap means type used for detainingly carry the electric circuit or any type of carrier for the push-button set 10, 14. On the electric circuit 31 manually operatable push-buttons can be arranged directly on the electric circuit by soldering, whereby an actuation of any of said push-buttons 32 establishes an electrical contact with a respective contact point on the electric circuit.

[0023] In one embodiment of the present invention the actuation parts 34 are moveably controlled and arranged in each guidance 33. The device comprises holding means 30 by which the carrier 31 is so detainingly carried in the apparatus casing that one actuation part 34 belonging to each electric switching circuit in the frame 4 is located at a location directly below the membrane 35.

[0024] The upper cover shaped part 2 of the control unit 1 can serve both as a casing and as a membrane, through which the by the frame 4 carried electric switching circuits 32 are actuated. In this embodiment, each membrane 35 has been formed as a continuous part of the upper cover shaped part 2 and the outwards directed surface of the membrane has been formed to be tactile for each separate electric switching circuit. More particularly, the membrane has been divided into a number of sensible or tactile membranes that each one is formed so that it can be separated from the adjacent membrane and every such membrane can be brought to cooperate with the actuation part 34 at each electric switching circuit 32.

[0025] After this description of embodiments related to the control unit as disclosed in Fig. 1 - Fig. 3 now follows a description of other embodiments of the present invention.

[0026] The electric switching device comprises a cover shaped casing 1 , one or more in the casing included actuation parts 34 belonging to the respective electric switching circuit 32. The membrane creates a part of the casing 1 and is arranged as a protecting cover placed at a location adjacent above every actuation part 34, whereby the membrane during push-down is arranged to cooperate with the actuation part 34 so that electric connection in the switching device circuit is established or broken.

[0027] The switching devices 32 can be arranged on a carrier 31 , which carrier 31 is detainingly carried by holding means 30 in the cover shaped casing 1. As above mentioned, the electric switching circuit can also comprise a frame 4 included in the casing 1 . Alternatively, then the frame 4 may comprise holding means 30 by which the carrier 31 is detainingly carried in the frame 4. The frame 4 and the casing 1 are then configured so that when the casing is arranged on the frame 4, the actuation parts are in a location directly below the membrane 35.

[0028] In one embodiment of the invention, the frame 4 or the casing 1 comprise a guiding 33 for every actuation part so that one actuation part 34 belonging to each electric switch 32 is located in a hole in a corresponding guiding 33 in the frame 4 at a location directly below the membrane.

[0029] By arranging interfaces on the outwards facing side of the membrane, which are sensible by a user's finger tip and which are separating the actuation part belong to each switching device circuit from each other, a person can with his finger tips distinguish each actuation part from the other. The guiding 33 belonging to the respective actuation part has an enclosing upper edge 37 which is supported by and cooperates with the underside of the membrane 35.

[0030] As mentioned above, the cover shaped casing 1 comprises a combination of an elastic plastic material and a rigid plastic material. In one embodiment of the invention the membrane 35 forms a part of the elastic plastic material.

[0031] As best disclosed in Fig. 4, each membrane 35 is located concentric with the actuation part 34 by a respective electric switching circuit 32, whereby the membrane during push-down can be brought into collapse and thereby to cooperation with said moveable actuation part so that electric contact is established or broken. In order to establish this, there are interfaces on the outwards facing side of the membrane. The interfaces are sensible by a user's finger tip and are separating the actuation part belong to each switching device circuit from each other in such a way that a person can with his finger tips distinguish each actuation part below the membrane from the other. For example, by choosing plastic material with a suitably low stiffness it can be attended to that each membrane 35 resists repeated collapse, i.e. repeated inwards bending or push-down. In order to further improve the membrane's 35 ability to collapse and to cooperate with the actuation part 34 of the electric switching circuit 32 and not at least to facilitate for the operator to tactile locate each electric switch 32, the membrane is given a preferable bellow like ring shaped appearance with in alternating directions arranged beaded edges 36. That is, beaded edges 36 of alternating convex and concave shape or essentially in the form of a sinus curve with its curve shaped parts located one outside the other. By the bellow shaped appearance the membrane 35 has been given a certain amount of surplus material for increased elasticity, whereby the sinus curve shape can be varied depending on desired stroke length and other characteristics of the tactile membrane.

[0032] In one embodiment of the present invention, which best is disclosed in Fig. 4 and 5, the tactile membrane 35 has a thickness of material below the thickness of material of other parts of the upper cover shapes part 2. The relatively thinner material thickness of the membrane 35 is preferably within the interval 0,4-1 ,2 mm, while the other parts of the upper cover shaped part 2 has a material thickness within the interval 1 ,5-2,5 mm. In one embodiment of the invention, the outer beaded edge 36 of the membrane 35 is supported by the upper enclosing upper edge 37 of the guidance 33, whereby a series or a group of membranes 35 in an effective way can be separated from each other, so that a push-down of an adjacent membrane 35 in a push-button set 10, 14 does not affect the other during push-down.

[0033] With reference to Fig. 4 - Fig. 5 it is clear that the interface of each membrane 35 may comprise a middle part with a raised frame part 38 with an optional indentation 39, this in order to give a more exclusive impression and to increase the sensibility. In one embodiment, the raised frame part is enclosed by a hood 40 or a button made of, for example, a metallic material such as aluminum. Said hood 40 has a head like thickened upper part with a diameter essentially corresponding to the diameter of the raised frame part 38 and is attached in the indentation 39 by for example gluing.

In the schematic illustrations and in the description the electric switching circuits 32 or the electric switches are preferably described as push buttons, but it shall be obvious that also other type of electric switches, for example toggle switches, can be used. In one embodiment of an electric switching device according to the invention the electric switching circuit 32 and the actuation part 34 is constituted of two or more electrodes on the carrier 31 and an electric conducting area on the underside of the membrane 35. During push-down of the membrane 35 the conducting area is brought into contact with said electrodes and electric contact between the electrodes are established. When the membrane is released the electric contact is again broken. In alternate embodiments, a more sophisticated circuit is used where push-down leads to a retained electric contact even if the membrane is released. The electric contact is not broken again until a renewed push-down is performed. The conducting area on the membrane 35 can for example be formed by multi-material techniques.

[0034] With reference to Fig. ό and 7, the inventive electric switching device is disclosed integrated in a cover shaped apparatus casing manufactured by extrusion (Fig. 6) and by blow moulding (Fig. 7). Both methods are well known within the technical field and have, together with injection moulding, in common that manufacturing is performed with a granulate shaped base material of plastic which is fed into a screw/cylinder device. The base material is pressed through a tool (nozzle) arranged at the front of the device into a profile 50 with the desired cross section shape. In order to create an outwards closed and moisture proof apparatus casing 1 , the profile 50 is cut into the appropriate length and is provided with end gables 51 , manufactured by injection moulding of plastic and assembled with a respective end of the profile by welding. At certain areas of the mantel surface of the profile 50 where there are bores 52 or openings, membranes 35 are fitted which are provided with tactile interfaces and optional cover glass. The interfaces are creating a moisture proof and outwards closed casing, when connected with the edge of the bore by welding. Said bores 52 are preferably created by using chip removing manufacturing methods such as milling. With the aid of channel shaped grooves arranged at the inside of the profile or bore wall (not shown) carrier means 30 are created in which the electronic equipment, such as electric circuits or similar, inside the apparatus casing can be carried in a detaining way.

[0035] Relating to the by blow moulding manufactured apparatus casing 1 in Fig. 7, this is created in a known way by extrusion of a plastic mass through a tool (nozzle) into a tube or hose 54. The extruded hose 54 is inserted and enclosed in a mould room, created by moveable mould parts, whereupon the by the mould parts enclosed hose end is cut and blow up towards the inside wall of the mould room. The blow up is performed by a, in the hose inserted, blow pipe which is via a valve connected to a high pressure air source. The high pressure air source connection it cut and the mould parts are separated from each other for removal of the extruded and blow moulded container, who's geometric outer shape exactly corresponds to inner wall defined by the configuration, in order for it to cool down. In similarity to what is described above, there are, at certain areas of the mantel surface of the blow moulded body, bores 52 or openings in which there are fitted membranes 35 provided with tactile interfaces which are creating a moisture proof and outwards closed casing when connected with the edge of the bore by welding. The by blow moulding manufactured apparatus casing lack holding means 30 at the inside. In similarity to the above description of what is disclosed in Fig. 1-5, instead a prefabricated frame 4 is used as a holder and carrier of the necessary electronic components. That is, the frame is provided with as well holding means 30 for receiving electric circuits 31 as guidings 33 for cooperation with an actuation part 34 of a respective push-button 32 in contact with an electric circuit. The membrane 35, the frame 4 and the included electronics is together forming a pre-assembled continuous unit which is fitted into the bore and is, when connected with the edge of the bore by welding, creating a moisture proof and outwards closed apparatus casing 1.

[0036] The blow moulding process also makes it possible to integrate the membrane with the casing made of the same material. Double moulding techniques also make it possible to create different material mixes in different parts, for example with one material in the membrane and another material in an adjacent casing part. This technique is not limited to only two material mixes; it is also possible to use triple moulding to create combinations of three materials. This can be used to create a first material in the casing, a second material in the membrane and a third material in a coating on the membrane.

[0037] In Fig. 8 the inventive electric switching device is disclosed integrated in a cover shaped apparatus casing 1 manufactured during injection moulding of a head piece 56 and associated end gables 57, whereby closure of the manufactured unit is performed by welding. At certain areas of the mantel surface of the profile, where there are bores 52 or openings, membranes 35 are fitted which are provided with tactile interfaces and optional cover glass 58. In order to create a moisture proof and outwards closed casing, the membranes 35 are connected with the edge of the bore by welding. Electrical components can detainingly be carried by holding means 30 which optionally can be created on the inside of the injection moulded casing. Optionally, the electrical components can be carried directly by the frame 4, whereby, as described above, said frame with electronics and membrane together form a continuous and in the apparatus casing mountable unit. The membrane and the cover glass can also be integrated in the casing by a multi- material technique, such as double and triple moulding. Thereby it is possible to produce a complete casing with integrated membrane and cover glass directly in the moulding tool.

[0038] It shall be implied that the arrangement of the membranes 35 in a moisture proof way by wishing to combine the unique characteristics of two materials in the above described apparatus casings, can be done in several different and well known ways. Examples of such well known and established multi- material techniques are the mentioned double and triple moulding.

[0039] The electric switching device may comprise thermoplastic elastic material (TPE). This type of material is suitable for this manufacturing process due to good workability and a possibility to integrate one or more material mixes, which leads to cost efficiency and improved constructions. TPE also has good usability characteristics, such as elasticity in a large temperature area, chemical resistance and wear resistance. TPE comprises under classes such as thermoplastic urethane (TPU) and thermoplastic olefin (TPO).

[0040] The present invention is not limited to that described above and that disclosed in the figures and may be changed or modified in a number of different ways within scope of the following claims.

Claims

1 . An electric switching device comprising α cover shaped casing (1 ), one or more in the casing (1 ) arranged actuation parts (34) belonging to a respective switching device circuit (32), characterized in that a membrane (35) creates a part of the casing (1 ) and is arranged as a protecting cover placed at a location adjacent above every actuation part (34) whereby, during push-down, the membrane is arranged to cooperate with the actuation part (34) so that electric connection is established or broken.

2. The electric switching device according to claim 1 , further comprising a carrier (31 ) which is detainingly carried by holding means (30) in the cover shaped casing (1 ), on which carrier (31 ) said switching device circuits (32) are arranged.

3. The electric switching device according to claim 1 , further comprising a frame included in the casing (1), a carrier (31 ) , on which carrier (31 ) said switching device circuits (32) are arranged and holding means (30), by which the carrier (31 ) is detainingly carried in the frame (4).

4. The electric switching device according to claim 3, whereby the frame (4) or the casing (1 ) comprises a guiding (33) for every actuation part so that one actuation part (34) belonging to each switching device circuit (32) is located in a hole in a corresponding guiding (33) in the frame or at a location directly below the membrane.

5. The electric switching device according to claim A₁ whereby interfaces are arranged on the outwards facing side of the membrane, which are sensible by a user's finger tip and which are separating the actuation part belong to each switching device circuit from each other in such a way that a person can with his finger tips distinguish each actuation part from the other, whereby the guiding (33) belonging to the respective actuation part has an enclosing upper edge (37) which is supported by and cooperates with the underside of the membrane (35).

6. The electric switching device according to any of the above claims, whereby the cover shaped casing (1 ) comprises a combination of an elastic plastic material and a rigid plastic material and the membrane (35) forms a part of the elastic plastic material.

7. The electric switching device according to any of the claims 2-6, whereby the carrier (31 ) comprises an electric circuit.

8. The electric switching device according to any of the claims 2-7, whereby the holding means (30) comprises grooves arranged in the cover (1 ) or in the frame (4) into which grooves the carrier (31 ) is insertable, alternatively snap means into which the carrier (31 ) can be snapped

9. The electric switching device according to any of the above claims, whereby the membrane (35) has for every interface been given a certain amount of surplus material whereby the membrane during push-down can be brought into collapse and thereby to cooperation with said actuation part (34)

10. The electric switching device according to claim 9, whereby the membrane (35) is given a bellow like ring shaped appearance with in alternating directions arranged beaded edges (36), preferably of alternating convex and concave shape.

1 1 . The electric switching device according to claim 10, whereby the beaded edges (36) of the membrane (35) have essentially the form of a sinus curve with its curve shaped parts located radially outside each other.

12. The electric switching device according to any of the above claims, whereby the membrane (35) in the area of each interface has a thickness of material below the thickness of material of other parts of membrane.

13. The electric switching device according to any of the claims 10-1 1 , whereby the outer beaded edge (36) of the respective membrane (35) is supported by an upper edge (37) of the guidance (33).

14. The electric switching device according to any of the claims 10-13, whereby the interface of each membrane (35) comprises a middle part with a raised frame part (38).

15. A method for manufacturing of an electric switching device comprising cover shaped casing (1 ), whereby the device comprises a cover shaped casing (1 ), one or more in the casing (1 ) arranged actuation parts (34) belonging to a respective switching device circuit (32) and one membrane (35) arranged as a protecting cover over every actuation part, whereby the method is characterised by the following steps:

manufacturing of a casing (1 ) whereby the membrane (35) is created as a part of said casing (1 ) and is provided with interfaces which are sensible by a user's finger tip,

providing a carrier (31) onto which the electric switching circuit (32) is directly arranged,

arranging the carrier (31 ) in a detaining way in the casing so that an actuation part (34) belonging to each electric switching circuit (32) is located at a location directly below the membrane (35).

16. The method according to claim 15, whereby the casing (1 ) is manufactured by any of the following plastic forming methods: extrusion, blow moulding, injection moulding or a combination of these, whereby a bore (52) is created in the, in this manner, manufactured casing and that a membrane (35) provided with tactile interfaces is fitted and joined with an edge of said bore (52).