For a Low Load Sliding Intermediate Shaft in a Steering Column for Industrial Vehicles

Abstract

The invention refers to improvements to the intermediate shaft in the claims of the main patent to adjust the depth of the steering wheel to match the driver's measurements, to absorb vibrations which may be generated by the wheels and suspension up to the steering wheel, as well as acting as a safety measure to collapse in the event of an accident which may also be by using the corresponding screw/nut mechanisms comprising a nut rigidly connected to the intermediate shaft on one of the flat surfaces of the female shaft and a screw which turns on it tightening the male shaft via the adjustment spring, so that it gently slides (with a predetermined load deemed to be suitable for facilitating sliding it by hand).

Description

More specifically, the invention refers to improvements to the intermediate shaft in the claims of the main patent to adjust the depth of the steering wheel to match the driver's measurements, to absorb vibrations which may be generated by the wheels and suspension up to the steering wheel, as well as acting as a safety measure to collapse in the event of an accident which may also be by using the corresponding screw/nut mechanisms comprising a nut rigidly connected to the intermediate shaft on one of the flat surfaces of the female shaft and a screw which turns on it tightening the male shaft via the adjustment spring, operating in the following manner:

• • When the screw is not tightened, the male shaft gently slides (with a predetermined load deemed to be suitable for facilitating sliding it by hand) so that the operator who is working on the line to raise the column, is able to extend it without great effort, thereby facilitating vehicle assembly work using its steering pinion and/or the steering column.
  • Once the steering column has been assembled, the screws are then tightened so that the above sliding joint becomes a strong joint giving the steering system great torsional and hysteresis rigidity, due to the action of the force that the screw applies in the direction of its axis and due to the reaction of the triangular faces on the female shaft onto which the force is exerted.

The mechanism which is built into the intermediate shaft shall include as a minimum, a nut which, due to its intrinsic function it plays on the intermediate steering shafts, has to be safe and be able to operate with different coverings guaranteeing its function and aspect against unwanted environmental effects so that corrosion and/or loss or mechanical or chemical properties in the materials are avoided and/or guaranteeing the appearance requirements which may be required by the customer.

As stated in the above paragraph, the nut has to be safe, ensuring its perfect operation without it affecting the complete full of the screw. In order to do this, the nut may be, although not limited to, oval, with a plastic retainer, or similar, so that any unexpected loosening of the screw inserted into it is avoided. This function is only taken into account when there is no locking feature on the screw.

Similarly, the mechanical features and dimensions of the nut have to ensure that the thread safety ensures the above mentioned safety function with the properties of the screw lodged into it, with, as a general rule, the improved quality of the same.

If the dimensional characteristics of the thread are significant, the external properties are not so significant, with the nut being in the most suitable external shape and size (hexagonal, cylindrical, square or similar), to minimize the turning diameter of around the intermediate shaft.

The form of fixing the nut onto the flat surface of the female shaft forming part of the intermediate shaft, the joint between the nut and shaft has to be rigid, without this being limited to the method used to achieve this. Therefore, for example, welding, pinning the nut or encapsulating it without denigrating any other method, may be acceptable for achieving the required aim, that is to say the rigidity and consistency of the nut/female shaft joint.

One of the surfaces of the female shaft has to be prepared so that, firstly, depending on the way the nut is held, it is able to house the nut. Therefore, for example, this shall not be the same in the event that the nut is welded, which requires no previous preparation to the shaft, rather than the pinned nut, which shall require a calibrated diameter, or the encapsulated nut which shall require holding by the cage itself. Secondly, the female shaft has to be perforated, by any method (drilling, punching or other) so that it allows the screw to pass through it to fulfil its tightening function on the male shaft against the two triangular faces of the female shaft.

It has to be highlighted that the function of the screw is safety, with it being equipped with the means required to prevent it from loosening during the vehicle's assembly. In order to do this, without detriment to the possible use of any other method, any method available on the market may be used, such as, the trilobular system, sealed with nut holders or similar.

Notwithstanding the above, the shape of the screw head, where the screwdriver is applied, may be different, such as, hexagonal, Allen, Phillips or other, wherever these ensure the tightening torque not only for the operator, but also for the integrity of the tool applying the torque and for the screw itself, both on the head and on the thread.

As stated previously for the nut, the dimensional and material properties of the screw have to be appropriate for the torque to be applied and for the application of the same, with the quality and properties of the thread being the most appropriate.

Similarly, to determine the length of the screw, the diameter of the turning circle for the intermediate shaft has to be taken into account once the screw has been inserted into the nut holding it. It has to be emphasized that, as the turning has to be very limited, normally less than one turn, and due to the fact that it only has to move axially along the distance required to adjust it, which usually is less than the passage of the screw, the length of the same may actually be very short.

The advantages of the improvements described with the low load intermediate shaft in the main patent no. 200400175, are being able to combine an easy movement of the said axis, in the first part of the column assembly, when the screw is loose, for the shaft assembly with torsional and hysteresis rigidity (due to the subsequent tightening of the screw holding the slide.

Alternatively, another of the aims of this improvement, there is the option of converting the intermediate shaft into a sliding shaft with the option to adjust the sliding load and the torsional and hysteresis rigidity achieved by the increased or decreased axial movement of the screw as a consequence of the greater or lesser turning angle applied during its tightening to torque. This shall be of great use in the event that the shafts requiring to slide although with a great load, as is common in 4×4 vehicles and height adjustable columns where the pivoting point does not coincide with the centre of the universal joint on the column connection or, if not, when this universal joint moves spatially due to the adjustment movements

Moreover, the application of a sliding, triangular, intermediate shaft allows, because of the force of the screw applied to the opposing triangular faces, perfect adjustment that, even though possible, is not easy to achieve with shafts with other cross sections, whether these are circular (grooved or otherwise), double D shaped, right angled and other shapes, so that it safely and reliably prevents the play which is characteristic of intermediate shafts.

It is also appropriate to state that another of the these improvements in this configuration is the absence of noise caused by the effects of resonance which, being caused by parts outside the steering system, usually appear in the intermediate shaft as this is the weakest part of the chassis and bodywork joint. This improvements change the rigidity of the intermediate shaft, modifying the resonance frequency of the same and making noise inaudible which, in another way, appear in the system.

Field trials performed to check the suitability of these improvements on the environmental properties, to indicate its suitability in every type of temperature and operating conditions, the improvement is not in the shaft situation but in the engine section or in the passenger compartment.

Finally, the excellent behaviour with regard to wear has to be highlighted making this configuration ideal for intermediate shafts subjected to significant and demanding operating life and fatigue requirements. The possibility of adjusting the screw with a simple servicing operation allows the worn intermediate shaft, and therefore with its rigidity and angular play properties, to become a shaft with similar properties, if not the same properties as a new intermediate shaft.

Other details and characteristics shall be shown throughout the description below referring to drawings attached to this report demonstrating the main properties of the invention without the same being solely restricted to it.

Below is a list of the main parts in the invention which are shown in diagrams attached to this report; (10) intermediate shaft, (11) female part, (12 and 13) universal joint, (14) male part, (15) metal strip, (16) holding cage, (17) holding cage compartments, (18) screws, (19) nuts, (20) drilled holes, (21) openings, (22) shaft face (4), (23) screw base (18), (24) beveling.

FIG. 1 is a front elevation view of the intermediate shaft (10), the subject of these improvements in which the male shaft (14) is partially placed into the female shaft (11), on one of the ends of (11-14) the universal joints (12-13).

FIG. 2 is a rotated view compared to FIG. 1 with regard to the longitudinal shaft crossing (10) longitudinally.

FIG. 3 is a detail “1” according to FIG. 2.

FIG. 4 is a partial elevation view of the described intermediate shaft (10).

In one of the preferred implementations of these improvements as shown in FIGS. 1 and 2, the recommended improvements concentrate on the inclusion on a female shaft (11) on the intermediate shaft (10) of some openings (21), on at least one of the faces allowing the assembly of a mechanism formed by a nut (19) and a screw (18), with the latter passing through a drilled hole (20) in the nut (19).

FIG. 3 shows detail “1” according to FIG. 2, demonstrating how the bases (23) of the screw (18) rest on the upper surface of the metal strip (15) inserted in the cage (16), the rear of which (15) is in contact with the male shaft (14).

The nut (19) has been designed with a small lower bevel (24) which is supported on the opening (21).

Increased pressure on the bases (23) of the screws (18) on the metal strip (15), causes more or less retaining strength of shaft (14) with regard to shaft (11), in the assembly position of the steering column with the bases (23) not being in contact with the male shaft (14) and more specifically with the surface of the strips (15), depending on the loads required in each case, allowing the calculation of different base values to join more than two screws (18), as well as changing the magnitude of the base surface (23), its roughness and the distance between the screws (18) within the female shaft (11), so that it will be possible to attain values consistent with the loads which each car manufacturer assigns to the manufacture of the steering column.

Therefore without any need for applying the mechanism to more than one face (22) of the male shaft (14), the force of the screws (18) is transferred to the other metal strips (15), an effect produced as a consequence of the initial design of the transverse section of the triangular intermediate shaft.

Having sufficiently described this invention using the figures attached, it is easy to understand that any changes judged to be suitable may be made, whenever these changes do not alter of the essence of the invention summarised in the following claims.

Claims

1. “IMPROVEMENTS TO PATENT No. 200400175 FOR A LOW LOAD SLIDING INTERMEDIATE SHAFT IN A STEERING COLUMN FOR INDUSTRIAL VEHICLES” including a female element designed to house a male part by sliding it into it and at least one strip mounted between the same which has an irregular contact surface and that these strips are assembled between the male part and the female part and inside some housings for a holding cage which in turn is firmly attached to the external surface of the aforementioned male part, with the cage being solidly attached to the outside of the male part using ridges in its external surface, with this cage being located on the male part characterized by the fact that the strips (15) located on the cage (16) are pressed on by safety screws (18) and its bases (23) which cross the female shaft (11) by openings (21) in at least one of the faces of the female faces (11) by the intrinsic function of the intermediate shafts in vehicle steering having to be safe and, the threading and unthreading of these screws on safety nuts (19) resting on a lower bevel (24) on these openings (21).

2. “IMPROVEMENTS TO PATENT No. 200400175 FOR A LOW LOAD SLIDING INTERMEDIATE SHAFT TN A STEERING COLUMN FOR INDUSTRIAL VEHICLES” according to claim 1, wherein the sliding load the male shaft (14) with regard to the female shaft (11) and the rigidity and hysteresis characteristics of the intermediate shaft (10) depend on the number of screws (18) and the tightening applied to the shaft (11).

3. “IMPROVEMENTS TO PATENT No. 200400175 FOR A LOW LOAD SLIDING INTERMEDIATE SHAFT IN A STEERING COLUMN FOR INDUSTRIAL VEHICLES” according to claim 1, wherein the sliding load the male shaft (14) with regard to the female shaft (11) and the rigidity and hysteresis characteristics of the intermediate shaft (10) depend on the distance between the screws (18) in the shaft (11).

4. “IMPROVEMENTS TO PATENT No. 200400175 FOR A LOW LOAD SLIDING INTERMEDIATE SHAFT IN A STEERING COLUMN FOR INDUSTRIAL VEHICLES” according to claim 1, wherein the sliding load the male shaft (14) with regard to the female shaft (11) and the rigidity and hysteresis characteristics of the intermediate shaft (10) depend on the surface of the base (23) of the screws (18).