GB2256748A

GB2256748A - Solenoid switch for a starter for internal combustion engines

Info

Publication number: GB2256748A
Application number: GB9210452A
Authority: GB
Inventors: Walter Ruehle; Ngoc-Thach Nguyen
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1991-05-18
Filing date: 1992-05-15
Publication date: 1992-12-16
Anticipated expiration: 2012-05-15
Also published as: DE4116416A1; GB9210452D0; GB2256748B; FR2676508B1; FR2676508A1

Description

1 -1 2 1 0 ? 4' c

-1DESCRIPTION SOLENOID SWITCH FOR A STARTER IN INTERNAL COMBUSTION ENGINES

This invention relates to a solenoid switch for a starting device, and in particular, but not exclusively, to a pre-engaged-drive starting motor in an internal combustion engine having a magnetic core which is fitted with an armature guide sleeve providing a cylindrical section to accommodate an axially operating armature. the armature guide sleeve being surrounded by a relay coil and having a resilient device axially supporting the relay coil.

A solenoid switch of this type enables a high current to be switched on with a relatively low control current. The starter current of a starting device for an internal combustion engine can be. for example for a passenger vehicle, up to approximately 1000 A. and for a commercial vehicle up to approximately 2500 A. A mechanical switch (ignition and starting switch) is sufficient to switch on the low control current. The solenoid switch installed in the starter forms a combination of a starting motor solenoid with a relay. It therefore fulfils a dual function, namely it displaces a starter pinion to engage in a ring gear in the internal combustion engine and closes a contact bridge to switch to the main starter current.

C1 A solenoid switch is known (DE-OS 28 22 164) whose magnetic core is fitted with an annular step, on to which an armature guide sleeve is pushed. A part of the surface area of the armature guide sleeve is surrounded by a relay coil which is arranged on a winding support. An axially movable armature is arranged within the armature guide sleeve, with the armature lying laterally offset to this when the relay coil is not energized. If the relay coil is energized, then the armature is pulled into the winding. This armature movement is used on the one hand to axially displace the pinion and on the other hand to press on the contact bridge for the main current contacts. The relay coil is surrounded by a sleeve type housing, an end region of which is pushed onto a part of the armature guide sleeve lying away from the magnetic core. A spring is supported on the end region inside the housing, with the spring surrounding the armature guide sleeve and axially affecting a correspondingly allocated end surface of the winding support of the relay coil. In this way the winding support and thereby the relay coil are held in position.

In accordance with the present invention a solenoid switch for a starter of internal combustion engines is provided having a magnetic core which is OW -3fitted with a cylindrical section to accommodate an armature guide sleeve containing an axially operating armature, the armature guide sleeve being surrounded by a relay coil and having a resilient member axially supporting the relay coil, wherein the armature guide sleeve and the resilient member are formed as a single component in such a way that a radially extending region containing the resilient member is connected to the cylindrical section of the armature guide housing, the radially extending region being arranged between the magnetic core and a front surface of a winding support of the relay coil.

This has the advantage that the assembly is simplified, the type of construction is shorter and the relay coil is more guarded against vibrations and jarring.

In addition the armature guide sleeve and the resilient member are designed as a single component in such a way that a radially extending region, arranged between the magnetic core and an end face of the relay coil, containing the resilient member is connected to the cylindrical section of the armature guide sleeve. The armature guide sleeve is pushed with the cylindrical section onto an annular step in the magnetic core, and the radially extending region at its end lies between an end wall of the magnetic core and a front surface of the relay coil or rather a to, front surface of the winding support of the magnetic coil. As the armature guide sleeve and the resilient member are a single component, the latter is installed at the same time as the armature guide sleeve so that there is no additional operation necessary to install the resilient member. By forming the armature guide sleeve and the resilient device together, the relay is of a simpler and shorter construction which reduces the installation space and the weight.

According to a further development it is intended that the resilient member is formed by the radially extending region or a part thereof. Provided that the entire radially extending region is, for example, convexly curved in the direction of the relay coil, it forms as a whole the resilient member. It is, however, also feasible that the region extending in this way has spring free-standing blades and these form the resilient member.

In accordance with a preferred example the resilient member is formed by curved or corrugated sections of spring plate of the radially running region.

Furthermore, a housing which covers the relay coil and which is in particular designed like a sleeve is advantageously fitted. The housing is pushed with its end region onto a part of the armature guide c -5sleeve lying away from the magnetic core in such a way that the end region rests against the associated other front surface of the relay coil. This front surface can, when using a winding support, be the other front surface of the winding support mentioned. In this way the relay coil or rather its winding support is pushed against the resilient member so that the relay coil is secured so as to be vibration proof.

According to a further example it is intended that the end region of the armature guide sleeve opposite the radial region extends outwardly to form a support for the end region of the housing. In this way the housing is additionally fixed in its position relative to the magnetic core so that the free space within the housing accommodating the ring coil and the resilient member has a defined size which ensures that the relay coil is firmly pushed against the resilient force of the resilient member and is thus secured both safely and vibration proof. The end region facing outwards of the armature guide sleeve moreover, has the advantage that opposite the armature there is no sharp edged aperture in the armature guide sleeve which can damage the surface of the armature, which would cause a pull-in resistance which in turn would increase the force required to operate the armature and thus reduce the serviceable life of the solenoid switch. Furthermore the radially extending end region V1 forms a quasi labyrinth-type annular gap between the armature guide sleeve and the armature, which prevents undesirable fluids from penetrating the inside of the housing and the coil. This reduces the risks of corrosion and short circuits. In the prior art where the armature guide sleeve is not provided with an outwardly extending end region, the capillary action of the axial annular gap on the coil body encourages the penetration of fluids, which can jeopardise the safe functioning of the solenoid switch. Also, the sharp edge of the armature guide sleeve of the known relay has the effect that vibrations cause damage to the surface of the armature.

Preferably it is intended that the end region is flanged towards the outside from the cylindrical section of the guide sleeve.

Similarly it is also expedient to curve the radially running region towards the outside from the cylindrical section of the anchor guide sleeve. Preferably the radially extending region can be produced as a resilient member by a drawing, stamping and compression moulding process, preferably in a single operation.

By way of example only, the present invention will now be described, with reference to the accompanying drawings, in which:

Fig.1 is a longitudinal sectional view through one embodiment of a solenoid switch constructed in accordance with the present invention; Fig.2 is a plan view of an armature guide sleeve of the solenoid switch of Fig.1; Fig.3 is a longitudinal sectional view through a part of the armature guide sleeve of Fig.2; and Fig.4 is a plan view of the armature guide sleeve of Fig.2, however representing a front surface of a winding support of a relay coil on the solenoid switch.

Referring to Fig.1, the solenoid switch 1 has a magnetic core 2, an armature 3. a relay coil 4, an armature guide sleeve 5 and a housing 6.

The magnetic core 2 has an annular step 7 comprising an axial wall 8 and an end wall 9. A part 10 of a cylindrical section 11 of the armature guide sleeve 5 is pushed onto the axial wall 8 of the annular step 7. Adjacent to the magnetic core 2 located on the outer surface area of the armature guide sleeve 5, there is a winding support 12 on which is arranged the relay coil 4.

The housing 6 in the form of a sleeve covers the relay coil 4 and has a smaller diameter end region 13, which is pushed onto a part 14, lying away from the magnetic core of the armature guide sleeve 5 in such a way that it rests against a front surface 15 of the cl winding support 12, and in so doing pushes the winding support 12 together with the relay coil 4 in the direction of the end wall 9 of the annular step 7. The other region 16 of the housing 6 is supported on a housing cover 17 of a contact chamber 18. The housing cover 17 is penetrated by two main current contacts 19, whose electrodes 20 can interact with a contact bridge 21.

The armature 3 has an extension 22 for operating the pinion of a starter motor, not illustrated, of a starting device of an internal combustion engine. A return spring 23 is supported at one end on the magnetic core 2 and at the other end on the armature 3 and holds the latter, when the relay coil 4 is not energized, in the position illustrated in Fig.l.

The magnetic core is penetrated by an opening 24 in which a bearing bush 25 is arranged. The bearing bush 25 is penetrated by a part of a divided switching pin 26 with the other part being located on the armature 3. The contact bridge 21 is attached to the part first mentioned of the switching pin 26, inside the contact chamber 18. A spring 27 is supported at one end on the housing cover 17 and at the other end on the front side 28 of a support 29 of the switching pin 26 and thereby holds the contact bridge 21, when the relay coil 4 is not energized. in the position illustrated-in Fig.l.

c It is essential that a radially extending region 30 is connected to the cylindrical section 11 of the armature guide sleeve, forming a resilient member 31. The region 30 lies between the end wall 9 of the annular step 7 and a front surface 32 of the relay coil 4 or rather of the winding support 12 of the relay coil 4.

The resilient effect of the resilient device 31 is achieved in that the region 30 of the armature guide sleeve 5 is preferably curvy or corrugated. The material of the armature guide sleeve 5 therefore preferably has elastic characteristics.

At the other end of the armature guide sleeve 5 there is an end region 33 which, as viewed from the cylindrical section, extends outwardly in such a way that it forms a support 34 for the end region 13 of the housing 6.

Fig.2 shows that the radially extending region 30 of the armature guide sleeve 5 is fitted with spring blades 35, which form the resilient member 31. In order to simplify the illustration the end region 33 of the armature guide sleeve 5 is not illustrated in Fig.2. The individual spring blades 35 have convex curves, in the direction of the end wall 9 (see Fig.3). The end region 36 of each spring blade 35 has a concave curvature 37.

c Fig.4 shows an illustration corresponding to Fig.2, however, the front surface 32 of the winding support 12 is also illustrated.

When assembling the solenoid switch, the armature guide sleeve 5 fitted with winding support 12 and relay coil 4. is first pushed onto the annular step 7 of the magnetic core 2. Subsequently the housing 6 is then installed and secured by forming the end region 33. By resting the end region 13 on the associated front surface 15 of the winding support 12, the winding support 12 is pushed against the resilient device 31 with the corresponding front surface 32 and the resilient device 31 is supported on the end wall 9 of the annular step 7. In this way the relay coil 4 is secured against vibration.

The resilient device 31 can be produced in one operation by drawing, stamping and compression moulding. The number and arrangement of the spring blades 35 is dependent on the construction of the winding support 12. The end region 33 is preferably produced by a flanged process. The use of a flange prevents the fluid media from entering the inside of the housing 6 so that the relay coil 4 is protected from corrosion and the like.

The construction in accordance with the invention enables the weight to be decreased since the length of the solenoid relay is relatively small. Furthermore, -lithe cost of the components is reduced by the armature guide housing 5 and resilient device 31 being one component. Furthermore, the cost of assembling the solenoid switch is also reduced.

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Claims

-12CLAIMS

1. Solenoid switch for a starter of internal combustion engines, having a magnetic core which is fitted with a cylindrical section to accommodate an armature guide sleeve containing an axially operating armature, the armature guide sleeve being surrounded by a relay coil and having a resilient member axially supporting the relay coil, wherein the armature guide sleeve and the resilient member are formed as a single component in such a way that a radially extending region containing the resilient member is connected to the cylindrical section of the armature guide housing, the radially extending region being arranged between the magnetic core and a front surface of a winding support of the relay coil.

2. Solenoid switch as claimed in claim 1, wherein the magnetic core has an annular step which is formed by an axial wall and an end wall, and the armature guide sleeve is pushed on the axial wall and the resilient member rests on the end wall.

3. Solenoid switch as claimed in one of the aforementioned claims, wherein the radially extending region has free-standing spring blades.

4. Solenoid switch as claimed in one of the aforementioned claims, wherein the resilient member is formed by curved or corrugated sections of spring plate or blades of the radially extending region.

c

5. Solenoid switch as claimed in one of the aforementioned claims, wherein the resilient member is supported on the front surface of a winding support of the relay coil.

6. Solenoid switch as claimed in one of the aforementioned claims, wherein the end region of a housing covering the relay coil is pushed onto a part laying away from the magnetic core of the armature guide sleeve.

7. Solenoid switch as claimed in claim 6, wherein the end region of the housing rests against the other front surface of the winding support.

8. Solenoid switch as claimed in one of the claims 6 or 7, wherein the end region, opposite the radially extending region of the armature guide sleeve extends outwardly to form a support for the end region of the housing.

9. Solenoid switch as claimed in claim 8, wherein the end region of the armature guide sleeve curves towards the outside from the cylindrical section of the armature guide sleeve and is in particular flanged.

10. Solenoid switch as claimed in one of the aforementioned claims, wherein the radially extending region curves away from the cylindrical section of the armature guide sleeve.

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11. Solenoid switch as claimed in one of the aforementioned claims, wherein the radially extending region and/or the resilient member are produced by a drawing, stamping and compression moulding process in a single operation.

12. A solenoid switch, constructed and adapted to operate substantially as herein described, with reference to and as illustrated in the accompanying drawings.