Patent Description:
This type of electrical contact block is known. An example is disclosed in <FIG> and <FIG> of <CIT>.

Such a contact block has the advantage of a low profile. However, it is not fully stackable, which limits its use as a module, for example as part of a push button assembly. In particular, this prior art contact block cannot be used as an upper or intermediate member of a contact block stack.

Another known type of electrical contact block is disclosed by <CIT>. However, this type of contact block has a comparatively high profile.

In view of the above, it is an object of the present disclosure to provide a low-profile electrical contact block, which is fully stackable.

According to the present disclosure, this object is achieved with an electrical contact block according to independent claim <NUM>.

By making the housing's bottom side into a connection interface, the contact block of the present disclosure can be easily stacked onto another component, and in particular onto another contact block. During stacking, thanks to the bottom side entrance, the actuation head of the lower contact block can be inserted into the clearance of the upper contact block. As a result, the actuation head of the lower contact block is arranged below the pusher of the upper contact block so that it can cooperate therewith. By locating the bottom end of the return spring in the centre of the clearance, a peripheral part of the clearance remains unobstructed, which allows the insertion of the actuation head of the lower contact block into the upper contact block.

The following features can be optionally implemented, separately or in combination one with the others:.

These and other features and advantages are detailed in the following description of preferred embodiments and in the accompanying figures, of which:.

Reference is first made to <FIG>. These figures show an embodiment <NUM> of a stackable electrical contact block according to the present disclosure.

The electrical contact block <NUM> is designed to be integrated into a control unit, such as an industrial pushbutton assembly (cf. By actuating the electrical contact block <NUM>, one can break an electrical contact between two electrical terminals arranged within the contact block. In industrial applications, this allows to stop the supply of electrical current to an electrically driven installation. For example, the electrical contact block <NUM> may be used as part of an emergency stop pushbutton, e.g. to stop a production line in case of a hazard.

Generally, there are two types of electrical contact blocks, namely electrical contact blocks that are normally open and electrical contact blocks that are normally closed (the respective shorthand is NO for "normally open", and NC for "normally closed").

The electrical contact block <NUM> shown in <FIG> is of the NC-type. It is to be understood that the present disclosure not only covers NC-type contact blocks, but also NO-type contact blocks.

With reference to <FIG>, the electrical contact block <NUM> comprises a housing <NUM> that delimits its overall volume. The housing <NUM> consists of a housing cover 102a and a housing main body 102b. The cover 102a is fitted onto a lateral side of the main body 102b. In <FIG>, the cover 102a is removed in order to show the internal structure of the electrical contact block <NUM>. The housing <NUM> has a top side <NUM> and an opposite bottom side <NUM>.

The electrical contact block <NUM> includes the following components, which are all present within the housing <NUM>:.

The two wire inlet pairs <NUM> and <NUM> are located on opposite sides of the housing <NUM>. In other words, a first side of the housing <NUM> has two wire inlets, and a second opposite side of the housing <NUM> equally has two wire inlets. In the figures, only one wire inlet of each pair <NUM>, <NUM> is visible on each side of the housing <NUM>. <FIG> and <FIG> illustrate the electrical contact block <NUM> with inserted electrical wires W. When inserted, the wires W are in electrical contact with one of the two terminals <NUM>, <NUM>.

The bottom side <NUM> and the top side <NUM> of the housing <NUM> are each configured as a connection interface for connecting the contact block <NUM> to another component. In this way, the contact block <NUM> can be stacked on to, for example, other contact blocks. Likewise, another contact block can be stacked on top of the illustrated contact block <NUM>. This is shown in <FIG>. Accordingly, the electrical contact block <NUM> can be assembled with other components in order to build a control device such as an emergency stop pushbutton assembly.

When another contact block is mounted onto the top side <NUM> of the contact block <NUM>, it is fastened thereto with the help of a double hook <NUM> and an opposite fastening shoe <NUM>.

The bottom connection interface, i.e. the housing's bottom side <NUM> has an entrance <NUM>, see <FIG>. Preferably, the entrance consists of two parallel slits 128a and 128b.

The actuation pusher <NUM> can move between a resting position Pr and an actuated position Pa in order to establish a break an electrical contact between the first and second terminals <NUM> and <NUM>. Since the contact block illustrated in <FIG> is of the NC-type, the resting position Pr is a closed position where the contact bridge <NUM> bridges the gap between the two electrical terminals <NUM> and <NUM>. In this closed position, an electrical current can flow from one terminal to the other. All figures except <FIG> show the actuation pusher <NUM> in its closed or resting position Pr. In <FIG>, the actuation pusher <NUM> is depressed and positioned in its actuated position Pa.

The actuation pusher <NUM> is represented on its own in <FIG>. It has an actuation head <NUM>, a cross-link <NUM>, a spring end receiving zone <NUM> located on the cross-link <NUM>, and a two-pronged (left & right) bridge guiding base <NUM>. The actuation head <NUM> and the base <NUM> are connected via the cross-link <NUM>. The actuation pusher <NUM> has an elongated shape, which defines a central longitudinal pusher axis X - X. As can be seen for example in <FIG>, the actuation pusher <NUM>, when viewed from the side, essentially has the shape of the letter H. One will also note that the actuation head <NUM> of the actuation pusher <NUM> is fork shaped. The fork <NUM> has two prongs 130a and 130b.

The bridge guiding base <NUM> also has a fork shape with a first prong 134a and a second prong 134b. As apparent from <FIG> and <FIG>, the mobile contact bridge <NUM> is accommodated in-between the two base prongs 134a and 134b. Each prong 134a, 134b acts as an outer guiding wall for one side of the mobile bridge <NUM> so that the mobile bridge <NUM> can slide up and down within the actuation pusher <NUM>.

The outer lateral walls of the first prong 134a act as guiding surfaces for guiding the sliding motion of the mobile bridge <NUM>. A guiding slot <NUM> is arranged in the second prong 134b. The inner walls of the guiding slot <NUM> also act as guiding surfaces for guiding the sliding motion of the mobile bridge <NUM>.

Turning now to <FIG>, the mobile electrical contact bridge <NUM> is a metallic element with two lateral electrical contact points 116a and 116b, a central through hole 116c, a guiding notch 116d, and a guiding protrusion 116e. The guiding notch 116d cooperates with the outer lateral walls of the slot-less guiding prong 134a. The guiding notch 116d and the outer lateral walls thus together form an outer guiding assembly. The guiding protrusion 116e fits into the guiding slot <NUM> of the second guiding prong 134b. Hence, the guiding protrusion 116e and the guiding slot <NUM> together form an inner guiding assembly. Overall, the sliding motion of the mobile bridge <NUM> is guided by two lateral guiding assemblies, namely the outer guiding assembly and the opposite inner guiding assembly.

Alternatively, the mobile bridge <NUM> may be guided by two outer guiding assemblies or two inner guiding assemblies. In the first case, both guiding prongs 134a, 134b will be slot-less and the mobile bridge <NUM> will have two opposite guiding notches 116d. In the second case, both guiding prongs 134a, 134b will have a guiding slot <NUM> and the mobile bridge <NUM> will have two opposite guiding protrusions 116e.

Each contact point 116a, 116b cooperates with one of the electrical terminals <NUM> and <NUM>.

In the illustrated embodiments, the return spring <NUM> is a helicoidal compression spring. As apparent from <FIG>, it has a bottom end 114a close to the housing's bottom side <NUM> and a top end 114b close to the housing's top side <NUM>. The return spring <NUM> has a cylindrical shape, which defines a central longitudinal spring axis Y - Y. The longitudinal spring axis Y - Y coincides with the longitudinal pusher axis X - X. The return spring <NUM> extends through the contact bridge <NUM>. More specifically, the return spring <NUM> traverses the central through-hole 116c. The function of the return spring <NUM> is to bias the actuation pusher <NUM> into its resting position Pr. To do so, its top end 114b pushes against the pusher <NUM>, and its bottom end 114a pushes against the housing <NUM>.

The top end 114b of the return spring <NUM> is received in the spring end receiving zone <NUM> of the actuation pusher <NUM>. A spring supporting section <NUM> is formed in the housing's bottom side <NUM>. The spring supporting section <NUM> supports the bottom end 114a of the return spring <NUM>. As illustrated in <FIG>, the spring supporting section <NUM> is located in-between the two parallel slits 128a and 128b.

As best seen in <FIG>, a clearance <NUM> is located below the actuation pusher <NUM>, when the actuation pusher <NUM> is in its resting position Pr. The bottom end 114a of the return spring <NUM> extends into the clearance <NUM>. The entrance <NUM>, i.e. the two slits 128a and 128b, provide access to the clearance <NUM>. A central part 142a of the clearance <NUM> is taken up by the bottom end 114a of the return spring <NUM>. A peripheral part 142b of the clearance <NUM>, which surrounds the central part 142a, is an actuation head receiving space. As can be seen in <FIG>, the actuation head receiving space 142b is adapted for receiving the actuation head <NUM> of a component connected to the contact block via its bottom side <NUM>. The actuation head receiving space 142b is subdivided into two separate receiving zones. Each zone can receive one of the two prongs 130a, 130b of a fork shaped actuation head <NUM>.

With reference to <FIG>, the contact spring <NUM> biases the contact bridge <NUM> towards the first and second terminals <NUM> and <NUM>. As seen in <FIG>, the contact spring <NUM> is fitted into the base part <NUM> of the actuation pusher <NUM>. The top portion of the contact spring <NUM> pushes against the bottom side of the contact bridge <NUM>. The bottom portion of the contact spring <NUM> rests on a ledge <NUM> of the base part <NUM>. In the illustrated embodiments, the contact spring <NUM> is a helicoidal compression spring. Accordingly, it has a cylindrical shape. As shown in <FIG>, the return spring <NUM> extends through the contact spring <NUM>. Preferably, the contact spring and the return spring are arranged coaxially. In this case, they share a common longitudinal axis Y - Y. Preferably, the diameter of the return spring <NUM> is smaller than the diameter of the contact spring <NUM>.

We will now explain the operation of the electrical contact block <NUM>. In the resting position Pr, the actuation head <NUM> protrudes from the housing's top side <NUM>, cf. The electrical contact block <NUM> is then actuated by pushing the actuation pusher <NUM> into the housing <NUM>. This is done by depressing the actuation head <NUM>. The pressure exerted on the actuation head <NUM> has to be sufficient to overcome the opposing force exerted by the return spring <NUM>. The actuation pusher <NUM> then moves towards the housing's bottom side <NUM> until it reaches its actuated position Pa shown in <FIG>. In this position, the actuation head <NUM> is completely retracted into the housing <NUM>. The mobile contact bridge <NUM>, which moves in unison with the actuation pusher <NUM>, is separated from the electrical terminals <NUM> and <NUM>. Accordingly, the electrical contact between the first and second terminals <NUM>, <NUM> is broken.

In order to attach a contact block to the bottom side <NUM> of the contact block <NUM>, one has to insert the prongs 130a, 130b of the actuation head <NUM> of the contact block into the parallel slits 128a, 128b of the contact block <NUM>. In this way, the prongs 130a, 130b are brought into the actuation head receiving space <NUM> of the contact block <NUM>. As can be seen in <FIG>, where two contact blocks are assembled to form a stack, the two prongs 130a, 130b of the actuation head <NUM> of the lower contact block are arranged directly below the actuation pusher of the upper contact block. Accordingly, when the upper actuation pusher is depressed, the downward force is directly transmitted to the lower actuation pusher so that both contact blocks are actuated simultaneously.

<FIG> show a stack where the upper contact block is a normally-open block <NUM> and the lower contact block is a normally-closed block. The scope of the present disclosure also extends to these NO-type contact blocks, which have the same inventive design as to the bottom side entrance, the clearance below the actuation pusher, and the arrangement of the return spring, the contact spring and the contact bridge.

<FIG> is a perspective view of a pushbutton assembly <NUM>, including two stacks <NUM> and <NUM> of two contact blocks according to the present disclosure. The left stack <NUM> is made of an upper contact block <NUM> of the NC - type and a lower contact block <NUM> of the NO - type. The right stack <NUM> is made of an upper contact block <NUM> of the NO - type and a lower contact block <NUM> of the NC - type. Hence, the assembly <NUM> has a total of four contact blocks. With the help of a collar <NUM>, the four contact blocks amounted to a pushbutton <NUM>.

A particularity of the contact blocks <NUM>, <NUM> of the present disclosure is their low profile. Indeed, typically, the ratio between the height h and the length I of the housing <NUM> of the contact block is less than <NUM> (cf. Thanks to the small height h, more contact blocks <NUM>, <NUM> can be assembled behind a collar <NUM> and still fit into a slim control panel.

The new contact block architecture described in the present disclosure is particularly suited to meet all current customer needs:.

The contact blocks <NUM>, <NUM> of the present disclosure are also fully compliant with the industry safety standards regarding clearance and creepage distance.

Claim 1:
A stackable electrical contact block (<NUM>) comprising a housing (<NUM>) that delimits its volume, wherein the housing (<NUM>) has a top side (<NUM>) and an opposite bottom side (<NUM>), wherein the following elements are present within the housing (<NUM>):
- a first (<NUM>) and second (<NUM>) electrical terminal;
- an actuation pusher (<NUM>) adapted to move between a resting position (Pr) and an actuated position (Pa) in order to establish or break an electrical contact between the first and second terminals (<NUM>, <NUM>), the actuation pusher (<NUM>) having an actuation head (<NUM>), which, in the resting position (Pr), protrudes from the housing's top side (<NUM>);
- a clearance (<NUM>) below the actuation pusher, when the actuation pusher is in its resting position (Pr);
- a return spring (<NUM>) biasing the actuation pusher (<NUM>) towards its resting position, a bottom end (114a) of the return spring extending into the clearance (<NUM>); and
- a mobile electrical contact bridge (<NUM>) for establishing and breaking the electrical contact between the first and second terminals (<NUM>, <NUM>), wherein the contact bridge (<NUM>) is accommodated in the actuation pusher (<NUM>),
wherein:
- the housing's bottom side (<NUM>) is configured as a connection interface with an entrance (<NUM>) providing access to the clearance (<NUM>), for connecting the contact block (<NUM>) to another component,
- a central part (142a) of the clearance is taken up by the bottom end (114a) of the return spring (<NUM>), and a peripheral part (142b) of the clearance, which surrounds the central part (142a), is an actuation head receiving space adapted for receiving the actuation head (<NUM>) of a component connected to the contact block (<NUM>) via the connection interface,
characterised in that the return spring (<NUM>) extends through the contact bridge (<NUM>).