MECHANICAL ACTUATOR

A mechanical actuator for vehicles includes a ball nut having a hardened inner part defining a ball track, a malleable outer part comprising a riveting area with a riveting edge, and a bearing riveted with the riveting edge to the riveting area of the outer part of the ball nut.

FIELD OF THE INVENTION

The present invention refers to mechanical actuators comprising ball nuts and bearings and a process of manufacturing of mechanical actuators.

BACKGROUND OF THE INVENTION

Conventional ball nuts100as shown inFIG. 1comprise fixing means in the outer part of the ball nut100to permit the fixation of a bearing (not shown) adapted to be fixed to an outer surface120of the ball nut. The fixing means normally comprise a nut for a threaded surface110formed on the outer part of the ball nut100.

The use of a nut as fixing means in ball nuts is a space consuming technique that increases the manufacturing cost, time and complexity.

The present invention aims to solve at least the aforementioned limitations given by the use of nuts as fixing means in ball nuts.

SUMMARY OF THE INVENTION

The present invention relates to a mechanical actuator for the automotive industry. The mechanical actuator comprises a ball nut that does not require the use of a nut as fixing means for fixing a bearing. Consequently, a threaded surface suitable for receiving a nut and located on the outer part of the ball nut is not required anymore and hence, the manufacturing process of the ball nut is eased and accelerated, and the material cost is reduced.

In a first aspect, the present invention relates to a mechanical actuator for vehicles. The mechanical actuator comprises a ball nut. The ball nut comprises a hardened inner part that defines a ball track for allocating a rack and recirculating balls acting as a bearing. Furthermore, the ball nut comprises a malleable outer part comprising a riveting area with a riveting edge. The mechanical actuator further comprises a bearing riveted with the riveting edge to the riveting area of the outer part of the ball nut.

In some examples, the mechanical actuator further comprises a rack and a plurality of balls for the ball track allocated in the inner part of the ball nut.

In a second aspect, the present invention relates to a manufacturing process of a mechanical actuator for vehicles, the process comprises obtaining a ball nut comprising an inner part defining a ball track and a malleable outer part comprising a riveting area with a riveting edge. The process comprises performing induction hardening of the inner part of the ball nut to obtain a hardened inner part. The process further comprises riveting a bearing with the riveting edge to the riveting area of the outer part of the ball nut to obtain the mechanical actuator.

These and other objects, advantages and features of the invention will become apparent upon review of the following specification in conjunction with the drawings.

DESCRIPTION OF A PREFERRED EMBODIMENT

FIG. 2shows an example of a mechanical actuator200for vehicles according to the present invention.

The mechanical actuator comprises a ball nut210which comprises a hardened inner part220that defines a ball track. In this example, the material of the ball nut210is carbon steel. Other materials can be used in further examples. The inner part220is hardened by performing induction hardening. Hardening is needed for the structure requirements of the inner part200, where circulating balls are acting as a bearing for a rack adapted to be allocated in the inner part200of the ball nut210. Induction hardening permits a hardening of selected parts of the ball nut210while keeping other parts unhardened and hence, more malleable and ductile.

Furthermore, the ball nut210comprises a malleable outer part230. The malleable outer part230comprises a riveting area230awith a riveting edge230b.As mentioned, the induction hardening is only performed to the inner part220of the ball nut210so the outer part230having the riveting area230aand the riveting edge230bremains ductile, and hence; as shown in the zoom ofFIG. 2, a riveting of the bearing240with the riveting edge230bcan be easily carried out without resulting in cracks.

As shown inFIG. 2, the bearing240(having bearing balls shown inFIG. 4) is riveted with the riveting edge230bto the riveting area230aof the outer part230of the ball nut210. As previously mentioned, for this riveting to be possible, the ball nut outer part230material needs not to be hardened and remain ductile. The riveting of the bearing240as a fixation procedure permits avoiding the use of conventional fixation means as nuts. As mentioned, the threaded surface for a nut on the outer part of the ball nut is not required anymore. Consequently, the manufacturing process is eased and accelerated and the outer part230surface of the ball nut210is decreased permitting a material cost reduction.

FIG. 3shows another section of the mechanical actuator200comprising the ball nut210and the bearing240fixed to the ball nut210by riveting said bearing240with the riveting edge230bto the riveting area230aof the outer part of the ball nut210. As shown inFIG. 3, the bearing240comprises a circular track for bearing balls that are shown inFIG. 4.

FIG. 4shows a first view of the mechanical actuator200showing the bearing240comprising a circular track with bearing balls.FIG. 5shows another view of the mechanical actuator200with the bearing240riveted to the ball nut210.

Furthermore, in further examples not shown, the mechanical actuator200comprises, in the inner part220, a rack and a plurality of balls for the ball track of the hardened inner part wherein induction hardening is performed.

It will be appreciated that the invention is not limited to the embodiment(s) described herein, but can be amended or modified without departing from the scope of the present invention, which his intended to be limited only by the scope of the appended claims as interpreted according to the principles of patent law including the doctrine of equivalents.