CONNECTING JOINT

Technical field

This invention relates to a connecting joint and in particular a joint for connecting a shaft of a motor with a transmission device, for example a speed reducer, to which explicit reference will be made without thereby limiting the scope of the invention.

Background art

Joints are known comprising a first coupling element, designed to connected as one with the drive shaft, a second coupling element, designed to be connected as one with the speed reducer, and a third element made of elastic material, inserted between the first and the second element for transmitting the motion between them.

Examples of these prior art solutions are described, for example, in patent document EP1213501 in the name of the same Applicant or in patent document US509261. In these documents, the elastic element has a plurality of teeth which extend from a common elastic connecting ring.

Each tooth is positioned, in use, in the coupling joint between a corresponding tooth of the first coupling member and a tooth of the second coupling member.

There are also prior art embodiments wherein the second coupling element is made directly, for example, in the head of a worm screw or in a cylindrical sleeve forming part of the speed reducer.

The elastic component, interposed between the coupling elements, makes the connection between the drive shaft and the speed reducer at least partly elastic.

This type of connection allows, amongst other things, slight offsets between motor and transmission device, reduces the level of vibrations present, improves the motion transmission limiting the consumption of the components involved and reduces the overall noise. A drawback of the prior art solutions derives from the fact that the couplings are made of three separate components, one attached to the motor, one attached to the transmission device or integrated in it and the elastic component interposed between the two and this architecture may be relatively complex to assemble.

Moreover, as mentioned, the couplings are carried out using teeth suitably provided in the three components of the joint and these teeth are stressed, in use, with bending which is a particularly stressful.

The presence of three components also determines a significant increase in the mass and the moment of inertia of the system with correlated problems linked, for example, to the balancing of the joint.

The need therefore remains unsatisfied for connecting joints with simpler architectures, with a smaller number of components to be dealt with and reduced masses and wherein the forces to which the components are subjected are optimised.

Disclosure of the invention

In this context, the aim of the invention is to provide a connecting joint which is able to satisfy the above-mentioned requirements.

In particular, the aim of the invention is to provide a compact connecting joint, with a reduced number of components and easy to assemble.

This aim is achieved by a connecting joint comprising the technical features described in one or more of the accompanying claims. The dependent claims correspond to possible different embodiments of the invention.

According to a first aspect, the invention relates to a connecting joint for connecting a first rotary element to a second rotary element, for example the shaft of a motor to a speed reducer or to another transmission device.

According to one aspect, the first and the second rotary elements rotate, in use, about an axis of rotation and the joint rotates about the axis of rotation. According to one aspect, the joint comprises a coupling unit connectable as one with one of the rotary elements, for example the shaft of a motor.

According to one aspect, the coupling unit comprises a main body, for example with a substantially annular shape, in which seats or cavities are made each configured to receive a respective engagement element, for example a tooth or the like, associated with the second rotary element.

According to one aspect, the engagement elements which are inserted in the seats of the coupling element do not form part of the joint and are, for example, formed directly in the second rotary element, for example a worm screw of a reduction gear unit if the coupling element is attached to the shaft of a motor.

According to an embodiment, the engagement elements which are inserted in the seats of the coupling element are part of a second coupling element provided for being connected to the second rotary element.

In this case, the connecting joint may comprise both the coupling elements.

According to one aspect, the seats in the coupling element are preferably each delimited by a bottom wall, preferably substantially transversal to the axis of rotation.

According to one aspect, the seats in the coupling element are preferably delimited, each by a lateral wall extending from a bottom wall substantially in the direction of the axis of rotation.

The bottom wall and/or the lateral wall of each seat define or delimit a corresponding recess for a transmission tooth associated with the second rotary element.

According to one aspect, the connecting joint comprises a plurality of elastic covering elements each positioned in a respective seat and fixed and/or made integral with the main body of the first connecting element.

In that way, each seat or recess is provided, at least partly, with an elastic covering. According to one aspect, the elastic covering of each seat, determined by the presence of the corresponding elastic covering element inserted in the recess, is positioned, in use, between a tooth associated with the second rotary element and the main body of the coupling element connectable to the first rotary element.

According to one aspect, the elastic covering element has an outer lateral surface shaped to match a lateral wall of the seat in which it is inserted.

According to one aspect, the elastic covering element has a bottom surface shaped to match a bottom wall of the seat in which it is inserted.

According to one aspect, the elastic covering element has an inner lateral surface shaped to match an outer lateral surface of the corresponding engagement element associated with the second rotary element.

According to one aspect, the inner lateral surface and the outer lateral surface of the elastic covering element extend from a base of the elastic covering element and define a lateral wall.

The lateral wall of the elastic covering element laterally delimits, inside the respective recess, the space for the corresponding engagement element associated with the second rotary element.

According to one aspect, each elastic element delimits, in the respective seat of the main body, a compartment for receiving the engagement element of the second coupling element.

According to one aspect, the connecting joint comprises a system for fixing the elastic covering element in the seat in the main body of the coupling element.

According to an embodiment, the elastic covering element is overmoulded on the main body of the coupling element.

The fixing system comprises, in practice, overmoulding, that is to say, the elastic covering element is fixed to the main body thanks to the fact that it is overmoulded on it.

According to one aspect, the covering elements of the seats are, in practice, in a single body with the main body of the coupling element. According to a preferred embodiment, the elastic covering element, that is, each elastic covering element co-moulded on the main body, has a shank inserted in the main body which has, for example, a hole in which the shank engages.

According to one aspect, according to an embodiment, the elastic covering elements can be mechanically coupled to the main body inside the respective seat.

The system for fixing the elastic covering element in the seat may comprise a fitting of the elastic covering element in the seat.

According to an embodiment, the fixing system may comprise at least one clip, extending for example from the elastic covering element, and a contact and engagement housing for the clip formed in said main body.

According to one aspect, the clip may comprise at least one flexible arm extending from the elastic covering element mainly according to a direction parallel to the axis of rotation and which is inserted in the contact and engagement housing.

The arm and the housing are configured or shaped in such a way that the elastic covering element is held in the respective seat.

According to one aspect, the elastic covering elements present in the joint can be connected to each other in such a way that they can be handled more simply.

According to a further aspect, the invention relates to a process for assembling a connecting joint comprising the steps of preparing a main body of a connecting joint, for example a joint according to one or more of the above-mentioned aspects, equipped with at least one seat or cavity configured to receive an engagement element, for example a tooth or the like, associated with the second rotary element and the step of fixing the elastic covering element in the seat.

According to one aspect, the step of fixing the elastic covering element in the seat may comprise a step of moulding the elastic covering element and a step of coupling said elastic element to the main body, inserting it in the seat.

According to one aspect, the step of coupling the elastic element to the main body may comprise a step of inserting a clip extending from the elastic covering element, in a contact and engagement housing for said clip made for example in the main body.

According to another aspect, a process for assembling a connecting joint comprises a step of overmoulding an elastic covering element on the main body of the first coupling element at a respective seat.

Further features and advantages and other aspects are more apparent in the non-limiting description which follows, with reference to preferred, nonlimiting embodiments of a connecting joint designed to couple two rotary elements.

Brief description of drawings

The description is set out below with reference to the accompanying drawings which are provided solely for purposes of illustration without restricting the scope of the invention and in which:

Figure 1 illustrates a schematic perspective view, partly exploded, of a schematic example of application of a connecting joint according to the invention;

Figure 2 illustrates a schematic cross section of a detail of an embodiment of a connecting joint according to the invention;

Figure 3 illustrates a schematic perspective view of a detail of an embodiment of a connecting joint according to the invention;

Figure 4 illustrates a schematic perspective cross section of a detail of an embodiment of a connecting joint according to the invention;

Figure 5 illustrates a schematic front view of a detail of an embodiment of a connecting joint according to the invention.

Detailed description of preferred embodiments of the invention

With reference to the accompanying drawings, the numeral 1 denotes a connecting joint according to this disclosure. The numeral 100 in Figure 1 denotes a preferred example of application of the joint 1.

In the example illustrated, the joint 1 is used for connecting a first rotary element 101 , for example the shaft of a motor, to which reference is hereinafter made without limiting the scope of the invention, with a second rotary element 102, for example a worm screw of a reduction gear unit, to which explicit reference is hereinafter made without thereby limiting the scope of the invention.

The application 100 rotates about an axis of rotation R which is adopted for simplicity as the axis of rotation of the joint 1 .

For the purposes of transmitting the motion, the connecting joint 1 comprises, in the example illustrated, a first coupling element 2 which is connectable, and connected, as described below, as one with the shaft 101.

The joint 1 also comprises a second coupling element 3 equipped with respective engagement elements 4, for example teeth, for engaging with the first element 2 and transmitting the motion.

In the example illustrated, the engagement elements 4 are formed directly on a head of the screw 102 of the reduction gear unit which defines, itself, the second coupling element.

According to alternative embodiments not illustrated, the second coupling element 3 is defined by a separate element which is connected to the second rotary element 102. In that case, the element connectable or connected to the second rotary element 102 may be considered as part of the joint 1.

Generally speaking, the engagement elements 4 are associated with the second rotary element 102.

In the context of the invention, the joint 1 is in any case considered also defined only by the first coupling element 2, regardless of how the second coupling element 3 is made. As illustrated, the first coupling element 3 comprises a main body 5, preferably metallic, for example made of aluminium alloy.

The body 5 is substantially annular in shape and has a central hole 6 so that it can be fitted on the shaft 101.

According to the embodiments illustrated for example in Figures 1 and 5, the body 5 is configured to be clamped on the shaft 101 in such a way as to transmit torque substantially by friction.

The body 5 has a notch 7, thus being in the form of an open ring.

The element 2 comprises, in the example illustrated, a lead nut and screw system 8, with an axis R8 skew relative to the axis R, for clamping the body 5 on the shaft 101 ; the system 8 defines a system for clamping the first element 2 for coupling to the shaft 101 .

According to an embodiment, the body 5 has a seat 9 for a tab, not illustrated, provided for also engaging with the shaft 101 .

The tab may also be the tab of the shaft 101.

Preferably, the tab is used as position reference of the joint 1 on the shaft 101.

As illustrated, the coupling element 2 comprises at least one seat 10, formed in the main body 5, configured to receive a corresponding tooth 4 of the second coupling element 3.

According to a preferred embodiment illustrated by way of example, the body 5 has three seats 10 for receiving as many elements 4 for engaging the second coupling element 3; according to other embodiments not illustrated, the body 5 has a different number of seats 10. The seats 10 are substantially similar to each other and, for simplicity of description, reference is also made to a single seat 10.

The seat 10 is in the form of a notch for receiving the corresponding tooth 4, that is to say, the seat 10 is formed in the main body 5.

The seat 10 is, for example, delimited by a bottom wall 11 transversal to the axis R of rotation, that is to say, it is at least partly closed by the wall 11. The seat 10 is, for example, delimited laterally by a lateral wall 12 which extends away from the bottom wall 11 preferably parallel to the axis R.

In the example illustrated, the lateral wall 12 comprises an outer annular wall 12a which surrounds all the seats 10 and a plurality of sides 12b which extend from the wall 12a towards the axis of rotation. The wall 12a together with the sides 12b delimits the seats 10.

According to alternative embodiments, each seat 10 is delimited laterally by a corresponding lateral wall.

The wall which laterally delimits the seat has an edge 12c on the side opposite the wall 11 which at least partly delimits an opening 13 giving access to the seat 10 through which, in use, the corresponding engagement element 4 is inserted into the seat 10.

According to the embodiment illustrated, the seat 10 is delimited, at least partly, in use, by the shaft 101 .

The first connecting element 2 comprises an elastic covering element or plug, labelled 14, positioned in the seat 10.

According to the embodiment illustrated, the connecting element 2 comprises an elastic covering element 14 for each seat 10.

As illustrated, inserted in each seat 10 is the elastic element 14 which forms an elastic covering of the seat 10.

The covering is interposed, in use, between the respective tooth 4 of the second coupling element 3 and the main body 5 of the first element 2.

The covering of elastic material, obtained using the plug 14, interposed between the teeth of the second coupling element, for example the screw of the reduction gear unit, and the respective seats in the first coupling element makes the connection between the drive shaft and the speed reducer in the example illustrated at least partly elastic.

The elements 14, at least their lateral walls, are also stressed by pure compression.

This type of connection allows, amongst other things, slight offsets between motor and reduction gear unit, reduces the level of vibrations present, improves the motion transmission limiting the consumption of the components involved and reduces the overall noise.

Preferably, the elastic elements 14 are all equal to each other, for simplicity of description, reference is made below also to a single element 14 inserted in the respective seat 10.

According to the invention, the elastic covering element 14 of the seat 10 is fixed to the body 5, that is, it is made integral with it.

Preferably, each elastic covering element 14 of the seat 10 is fixed to the main body 5 of the coupling element 2 independently of the others.

The joint 1 preferably comprises a system for fixing the elastic covering element 14 in the respective seat 10, as described in more detail below.

With reference in particular to Figure 3, it may be noted that the element 14 has a portion 14a preferably substantially shaped like the seat 10 designed to house it.

As illustrated by way of example, the elastic covering element 14, and in particular its portion 14a, has a bottom wall 15 and a lateral wall 16 extending from the bottom wall 15.

The elastic covering element 14, in particular its bottom wall 15, has an bottom surface 17 preferably shaped to match the bottom wall 11 of the seat 10.

The elastic covering element 14, in particular its lateral wall 16, has an outer lateral surface 18 preferably shaped to match an inner lateral surface of the lateral wall 12 of the seat 10.

The elastic covering element 14, in particular its lateral wall 16, has an inner lateral surface 19 preferably shaped to match an outer lateral surface of the corresponding engagement element 4.

According to a preferred embodiment, shown for example in Figure 2, the element 14 is inserted in the seat 10 in such a way that the surface 17 abuts against the bottom wall 11 of the seat 10 and the outer lateral surface 18 abuts against the lateral wall 12 of the seat 10. The elastic element 14 delimits, in the seat 10, a compartment 20 for receiving the engagement element 4 so that the elements 14 are interposed between the first coupling element 101 and the second coupling element 102. According to the examples illustrated, the compartment 20 is delimited, at least partly, by the wall 15 and by the wall 16.

As mentioned, the joint 1 comprises a system for fixing each elastic covering element 14 to the body 5 in the respective seat 10.

According to an embodiment, the fixing system comprises a clip 21 extending from the elastic element 14, in particular from the portion 14a. Preferably, the covering element 14 comprises the clip 21 , preferably made in a single body with it.

The fixing system comprises a housing 22 for contact and engagement with the clip 21 formed in the main body 5.

As illustrated, the housing 22 extends from the seat 10, in particular from the relative bottom wall 11 , preferably along a direction parallel to the axis of rotation R.

In the example illustrated, the clip 21 comprises a pair of flexible arms 23 which are relatively movable between a close position for inserting in the housing 22 and a far position locked in the housing 22 at which the element 14 is locked in the seat 10.

The housing 22 has, for example, a contact element for the ends of the arms 23 at least when they are in the far position in such a way that the element 14 cannot be pulled out of the seat 10.

According to an embodiment, the seat 10 and the elastic element 14, in particular its portion 14a, are sized in such a way as to form a snap fitting once the element 14 is inserted in the seat 10.

According to an embodiment, the elastic covering elements 14 are overmoulded on the main body 5 of the coupling element 2. In practice, the system for fixing the elastic element 14 to the body 5 comprises the elastic covering element 14 overmoulded on said main body.

In order to fix the elastic element 14 to the body 5, the element 14 is overmoulded on the body 5.

With reference, for example, to Figure 4, it may be noted that preferably the overmoulded elastic covering element 14 comprises a shank 24 inserted in the main body 5.

The body 5 has a hole 25 extending from the bottom wall of the seat 10 where plastic material is injected during the moulding of the plug 14 in such a way as to make the shank 24 which contributes to the fixing of the element 14 to the body 5.

According to an embodiment not illustrated, separate plugs 14 may be interconnected or connected to each other by connecting arms.

A method for assembling the connecting joint 1 comprises the steps of preparing or making the main body 5 equipped with the seats 10 and fixing the elastic covering elements 14, each in the respective seat 10.

According to an embodiment, the plugs 14, for example moulded from plastic material, are positioned in the seats 10 and the respective clips 21 blocked in their housings 22 made in the body 5.

Preferably, the element 14 is shaped in such a way that the portion 14a is secured in the seat 10

According to an embodiment the step of fixing the elastic covering element 14 in the seat 10 comprises a step of overmoulding the elastic covering element 10 to the main body 5 of the first coupling element.

In practice, with the overmoulding the plugs 14 are made directly in the seats 10 on the body 5.

The coupling element 2 integrates, using the plugs 14, the elastic functions of the joint 1 .

Even during manipulation of the joint prior to a final assembly the elastic covering elements remain in the seats. The coupling is performed between elements engaged with each other wherein the elastic zones work by compression as the seats for the teeth have been made directly in the body of the joint.

In practice, the elastic elements and the seats in the main body fit around the engagement elements of the second coupling element.

The total mass of the coupling is reduced and the clearances are reduced between the body of the coupling element and the elastic elements which are, in effect, integrated in a single component.

The main clamp body is elastically clamped on the shaft of the motor; the joint also clamps on the teeth of the screw by a slight deformation, eliminating any gaps or assembly tolerances.

The presence of the tab, guaranteeing a position reference between the joint and the shaft, may allow an encoder normally provided not to be installed. In the case of plugs hooked in the seats, they are interchangeable.