1. Technical Field of the Invention
The present invention relates to an electromagnetically operated device for displaceably actuating a member for locking a rotating body.
2. Description of the Prior Art
It is known, for example in the technical sector of vehicles, to use differentials associated with rotating shafts which are controlled and associated with means able to cause locking of the said differentials when predetermined relative rotation conditions of the connected shafts exist.
It is also known that locking of the differential is performed by means of engagement between front teeth, associated with the axially fixed rotating crown wheel, of the differential and the front teeth of a rotationally fixed, but axially movable, locking crown wheel, displacement of which is controlled by means of pneumatic pistons.
Although fulfilling its function, this solution results in the need for a complicated and costly arrangement of fluid conveying pipes and headers as well as means for keeping under pressure the piston actuating fluid, which are also subject to possible losses in head resulting in malfunctioning of the locking engagement system.
The technical problem which is posed, therefore, is to provide a device for displaceably actuating a rotating crown wheel, in particular, but not exclusively, of a system for locking a differential, which is able to overcome the drawbacks of the prior art, being reliable and secure.
In connection with this problem it is also required that this device should have small dimensions, be easy and inexpensive to produce and assemble and be able to be applied easily also in combination with pre-existing installations.
These results are obtained according to the present invention by a device for displaceably actuating, in both directions along a longitudinal axis, a locking crown wheel, which device comprises an electromagnet actuator for displacing the crown wheel along the longitudinal.
Further details may be obtained from the following description of a non-limiting example of embodiment of the subject of the present invention provided with reference to the accompanying drawings in which:
a-4d show schematic cross-sections illustrating the operating sequence of the device according to the invention;
As shown in
In greater detail, the embodiment shown in
The armature 1112 is mounted on a bearing 1113 mounted in the axial direction on a rear sleeve 20a rigidly connected to the locking crown wheel 20.
As shown, the bearing 1113 is mounted on said sleeve 20a so as to leave an annular gap 1113a between the inner race of the bearing and the sleeve itself; the latter also has, mounted thereon, a ring 30b able to form a rear end-of-travel stop for the bearing 1113.
The armature 1112 also has seats 1112a with a bottom hole 1112b able to allow the insertion, in the longitudinal direction, of the said guide pins 1111 which are prevented from coming out towards the front by the respective head 1111a having a diameter larger than that of the hole 1112b.
First springs 1115 are arranged between the bearing 1113 and the locking crown wheel 20, said springs being axially arranged and inserted inside a respective seat 20c of the locking crown wheel 20; in the configuration shown in
As shown in
According to a preferred embodiment, it is also envisaged that the electromagnet 1121 is formed by a plurality of packed laminar elements 1121a so as to increase the force of attraction with respect to the armature 1112.
With this configuration and with reference to
According to the invention, moreover, that activation of the electromagnet 1121 for recalling the armature 1112 is performed with a brief overcurrent transient so as to obtain a recall force sufficient to bring the armature 1112 into contact against the said electromagnet, this condition allowing the power supply current to the electromagnet to be reduced to normal values since the force required to keep the armature in contact is much less than that required for initial recall thereof.
As shown in
With this solution it is possible to obtain an improved performance of the clutch system since the reduction in the air gap also allows a reduction in the initial overcurrent for recalling the armature.
As shown in detail in
Preferably the axial extension 1121C and the corresponding seat 1112C of the armature have a frustoconical shape so as to favour insertion, but, as shown in
It can therefore be seen how, with the axial actuating device according to the present invention, it is possible to achieve secure and reliable engagement/disengagement of the two sets of front teeth, which in the example described form part of a locking differential, avoiding the need for fluid conveying pipes and the associated problems for example due to possible losses in head and the like and ensuring safe operation due to the fact that duplication of the thrusting springs ensures safe recall of the armature and preparation of the crown wheel for engagement which can occur at any useful moment without damaging the electromagnet which otherwise would have to be kept in a condition where it is supplied with an overcurrent for long periods of time.
Moreover, owing to the particular characteristics of the electromagnet, which can be excited with an overcurrent transient, it is possible to reduce the dimensions and house completely the locking device inside the box of the differential, avoiding the need for parts and associated volumes outside of it.
Also, owing to the particular form of the bearing 1113 supporting the armature, which moves coaxially on the locking crown wheel without contact, it is possible to avoid wear from frictional contact as well as wear of the armature which, rotating on the outer race of the said bearing, is not subject to frictional forces resulting from contact in the axial direction with the end-of-travel stops.
Number | Date | Country | Kind |
---|---|---|---|
MI2006A001785 | Sep 2006 | IT | national |
MI2006A001983 | Oct 2006 | IT | national |