Non-contact switch devices for use on material handling equipment

The disclosure provides a non-contact switch device for use on material handling equipment, including a reed switch and a magnet, wherein the non-contact switch device has on and off positions achieved by the presence or absence of magnetic induction between the magnet and the reed switch. The non-contact switch devices are disclosed in the form of a main power switch, an interlock switch, a limit switch.

TECHNICAL FIELD

The invention relates to non-contact switch devices for use on material handling equipment, such as pallet trucks, pallet stackers and the like, wherein the non-contact switch devices realize switch on and off positions by the presence or absence of magnetic induction between a magnet and a reed switch. Depending on the structure of the non-contact switch device, switch actuation to move from the off to the on position may occur based on the presence or absence of a magnet and/or shielding or non-shielding of a magnet relative to a reed switch.

BACKGROUND

Material handling equipment is widely used in warehouses, stores and other facilities, and electric powered vehicles are continuing to become more popular for at least environmental and noise related advantages over gas powered vehicles. Electric powered vehicles also have advantages over manual powered vehicles relating to at least capacity, operator safety and efficiency. Electrical switches are commonly used on material handling equipment to realize different functions, such as a main key switch device having power on and off positions relating to providing power to the material handling equipment, an interlock switch device having on and off positions relating to being able to drive the material handling equipment, and a limit switch device having on and off positions relating to controlling movement of a load lift portion of material handling equipment.

Traditional contact switches used in material handling equipment generally are of a type of electro-mechanical switch or mechanical micro switch. Such switches provide a particular function by having the operator directly move an electrical contact to touch or engage another electrical contact in a specific position, such as when turning a key in a switch lock cylinder. The switches may require a fairly large volume, and tend to make switch design and layout somewhat difficult. The common switches used also have a relatively short service life because the contacts may be exposed to the atmosphere and their ability to function is subject to wear, corrosion and dirty working conditions. These issues can lead to increased costs due to downtime of the equipment and the need for maintenance or replacement.

SUMMARY

The subject matter of this disclosure provides advantages over the typical electrical switches normally used on prior art electrical material handling equipment, such as pallet trucks, pallet stackers and the like. The non-contact switch devices of the present disclosure include reed switch configurations that include switch elements in the form of a pair of contacts on ferrous metal reeds that are encapsulated within inert gas or a vacuum as they are hermetically sealed in a glass tube or chamber. As such, the reeds and contacts are not subject to the atmosphere, or the heavy wear, corrosion or dirty working conditions of the traditional switches. The sealed structure provides greater safety because they permit use of the non-contact switch devices in a corrosive atmosphere or in the presence of flammable or explosive gas.

The non-contact switch devices also are relatively compact, reliable and provide for easy design and layout, with simple actuation. The switches also can be designed with the reed contacts normally in an open position, so as to close when subjected to a magnetic field, or normally closed, so as to open when subjected to a magnetic field, with the reed contacts returning to their normal position when the magnet is removed or shielded from the reed switch.

This non-contact actuation based on the presence or absence of a magnetic field is in contrast to prior art electric switches used on material handling equipment that have switch contacts that require touching or engagement between contacts that also may be exposed to the atmosphere and suffer due to wear, corrosion and dirty conditions, leading to a short service life.

In a first aspect, the disclosure provides a non-contact switch device for use on material handling equipment, including a reed switch and a magnet, wherein the non-contact switch device has on and off positions achieved by the presence or absence of magnetic induction between the magnet and the reed switch.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and provided for purposes of explanation only, and are not restrictive with respect to the claimed subject matter. Further features and advantages will become more fully apparent in the following description of the example preferred embodiment and from the appended claims.

It should be understood that the drawings are not necessarily to scale. While some details of the material handling equipment, and other plan and section views of the particular components have been omitted, such details are considered to be within the comprehension of those skilled in the art in light of the present disclosure. It also should be understood that the present disclosure is not limited to the examples illustrated and described.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

This disclosure provides solutions to the technical problems presented by electrical switches commonly used for various functions when operating material handling equipment, such as are used in pallet trucks, pallet stackers and the like. Examples of non-contact switch devices that realize switch on and off positions by the presence or absence of magnetic induction between a magnet and a reed switch are shown in various forms inFIGS. 1A-5Cfor use on material handling equipment, such as a pallet truck. The non-contact switch devices are shown for example in the form of a main power switch1for a pallet truck inFIGS. 1A-1C, with a schematic view of the reed switch elements of that non-contact switch device inFIGS. 2A-2B, in the form of an interlock switch20on a handle of a pallet truck inFIGS. 3 and 3A-3C, with a schematic view of the reed switch elements of that non-contact switch device inFIGS. 4A-4B, and in the form of a limit switch40associated with movement of the load lift portion of the pallet truck inFIGS. 5 and 5A-5B, which also is represented by the schematic view of the reed switch elements of that non-contact switch device inFIGS. 4A-4B.

The non-contact switch devices1,20and40of the present disclosure are embodied in reed switch configurations that include reed switch elements in the form of a pair of contacts on the ends of reeds that are within a hermetically sealed glass envelope or chamber. At least one of the reeds is constructed using ferromagnetic material, such as a ferrous metal, for example iron, cobalt and nickel, while depending on the design, the other reed may be constructed using non-magnetic material. The reed switch elements may be predisposed to normally be open or spaced apart when not in the presence of a magnet, so as to close or touch together in the presence of a magnet, such as in the non-contact switch device1represented inFIGS. 1A-1C and 2A-2B. Alternatively, the reed switch elements may be predisposed to normally be closed or touching together when not in the presence of a magnet, so as to open or move to be spaced apart in the presence of a magnet, such as in the non-contact switch devices20and40represented inFIGS. 3 and 3A-3C, 4A-4B, 5 and 5A-5C. It will be appreciated that the reed switch may be designed to have one or both reeds move when subjected to a magnetic force.

As shown inFIGS. 1A-1C, the disclosure provides a first example non-contact switch1that is a main power switch, which includes a magnet2and a reed switch3. The reed switch3is held within and connected to a switch body4that includes a switch socket5and may be mounted on a surface of material handling equipment for convenient access by an operator, such as on a top surface of a pallet truck or the like. The magnet2may be a permanent magnet and is held or embedded within a magnet cap6, which simply otherwise may be constructed of plastic and which is removably receivable in the switch socket5.

As seen in the schematic view inFIGS. 2A and 2B, the reed switch3includes reed elements7and8that are encapsulated within inert gas or a vacuum as they are hermetically sealed in a glass tube or chamber9. In this example, as seen inFIG. 2A, the non-contact switch device1is normally in an open position because the reed elements7and8are normally in a spaced apart position when not in the presence of the magnet2. When the magnet cap6is placed in the switch socket5, the magnet2is brought into close proximity of the reed switch3. The magnetic field caused by the presence of the magnet2causes the reed element7to be attracted to and move toward the magnet2, which results in the reed element7moving into contact with the reed element8, closing the reed switch3and thereby moving the non-contact switch device1to an on position.

The non-contact switch device1including the magnet2and magnetic reed switch3preferably provides an easier structure to employ, requires a smaller volume, is actuated at a faster speed, and yields a longer service life than traditional mechanical switches used on material handling equipment. The non-contact switch device1also has stronger resistance and is more reliable than electric switches. Its switching reed elements7and8are sealed in an inert gas or vacuum, and are not in contact with the external environment. This greatly reduces the co-oxidation and carbonization by contacts during the opening and closing process. It also prevents external vapor, dust and other impurities from eroding the contacts.

Thus, a first example non-contact switch device1is represented inFIGS. 1A-1C and 2A-2B. The non-contact switch device1for use on material handling equipment includes a magnet2and a reed switch3, wherein the non-contact switch device1has on and off positions achieved by the presence or absence of magnetic induction between the magnet2and the reed switch3. The non-contact switch device1is in the on position when the magnet2is placed in close proximity to the reed switch3, and is in the off position when the magnet2is not in close proximity to the reed switch3.

The example non-contact switch device1has the magnet cap6that includes the magnet2and the switch socket5that includes the reed switch3. When the magnet cap6is placed in the switch socket5, the magnet2is in close proximity to the reed switch3and the non-contact switch device1is in the on position. When the magnet cap6is removed from the switch socket5, the magnet2is not in close proximity to the reed switch3and the non-contact switch device1is in the off position. In light of this disclosure, it will be appreciated that with the non-contact switch device1of the first example, the magnet cap6and switch socket5are part of a main power switch device for material handling equipment, such as a pallet truck, with the main power switch having a power on and off function corresponding to the on and off positions, wherein the magnet cap6may simply be removed and placed in a pocket when the equipment is not in use.

As shown inFIGS. 3 and 3A-3C, the disclosure provides a second example non-contact switch20wherein a magnet22and a reed switch23are in a spaced apart position and the non-contact switch device20is in the off position when a shielding member21is located between the magnet22and the reed switch23, and is in the on position when the shielding member21is not located between the magnet22and the reed switch23. The second example non-contact switch device20is in the form of an interlock switch. The magnet22and reed switch23may be connected to the same component, such as a bracket, and are connected to a base portion24of a pallet truck P and are spaced apart by a gap25. The magnet22may be a permanent magnet. The shielding member21is connected to an operator handle26that pivots relative to the base portion24, and the shielding member21may have more than one extensions that act as a shield.

With the second example non-contact switch device20, the magnet22and the reed switch23are spaced apart by the gap25and the non-contact switch device20is in the off position when the shielding member21is located between the magnet22and the reed switch23, and is in the on position when the shielding member21is not located between the magnet22and the reed switch23.

As seen in the schematic view inFIGS. 4A and 4B, the reed switch23includes reed elements27and28that are encapsulated within inert gas or a vacuum as they are hermetically sealed in a glass tube or chamber29. In this example, as seen inFIG. 4B, the non-contact switch device20, which has the magnet22and reed switch23in fixed positions with the gap25therebetween, normally is in a closed position because the magnet22attracts the reed element27toward and into contact with the reed elements28. When the shielding element21is moved to be located in the gap25between the magnet22and the reed switch23, as seen inFIG. 4A, the reed element27returns to a pre-deflected position spaced apart from reed element28, opening the reed switch23, so as to be moved to the off position.

While this second example non-contact switch device20includes a shielding member21, it will be appreciated that the non-contact switch device20also operates in response to the presence or absence of a magnetic field between the magnet22and the reed switch23.FIG. 3is a side view of the pallet truck P showing the operator handle26in three example positions A, B and C, which provide different operational states of the non-contact switch device20in the form of an interlock switch.

The example pallet truck P is shown with the operator handle in a generally vertical parked position A, an angled operating position B, and a generally horizontal inactive position C. A close up view of the non-contact switch device20inFIG. 3Acorresponds to the generally parked position A of the operator handle26. With the operator handle26essentially fully upright in a parked position, the shielding member21is located between the magnet22and the reed switch23, placing the non-contact switch device20in an open position, as shown inFIG. 4A. With the reed elements27and28no longer in contact, the power cannot flow through the reed switch23and a controller prevents the pallet truck P from being driven.

When an operator wishes to drive the pallet truck P, the operator may grasp the operator handle26and tilt it to an inclined operating position, such as position B. The operating position generally may be at an angular position anywhere between the generally vertical or fully upright position A and the generally horizontal or fully lowered position C. In an operating position B, the shielding member21that is connected to the operator handle26is moved so as to no longer be located in the gap25between the magnet22and the reed switch23, as represented inFIGS. 3B and 4B. This permits the reed switch23to close, which corresponds to being in the on position shown inFIG. 4B, wherein power is able to flow through the reed switch23and a controller makes the pallet truck P drivable. Thus, the operator is able to utilize the controls on the operator handle26to operate and drive the pallet truck P.

If the operator were to inadvertently drop the operator handle26, it would move to the generally horizontal, fully lowered position C, shown inFIG. 3. This would result in the non-contact switch device20being in the position shown inFIG. 3C, wherein another shielding member21on the operator handle26is moved to be located in the gap25between the magnet22and the reed switch23. Thus, as a safety precaution, the non-contact switch device20would be opened and moved to the off position, rendering the drive system inactive when the operator handle is moved to a generally horizontal position C.

As shown inFIGS. 5 and 5A-5C, the disclosure provides a third example non-contact switch40wherein a magnet42and a reed switch43are in a spaced apart position and the non-contact switch device40is in the off position when a shielding member41is located between the magnet42and the reed switch43, and is in the on position when the shielding member41is not located between the magnet42and the reed switch43. The third example non-contact switch device40is in the form of a limit switch. The magnet42and reed switch43may be connected to the same component, such as a bracket, and are connected to a load lift portion44of a pallet truck P and are spaced apart by a gap45. The magnet42may be a permanent magnet. The shielding member41is connected to a rotating link46that pivots relative to the load lift portion44as the load lift portion44is raised or lowered.

With the third example non-contact switch device40, the magnet42and the reed switch43are spaced apart by the gap45and the non-contact switch device40is in the on position when the shielding member41is not located between the magnet42and the reed switch43, and is in the off position when the shielding member41is located between the magnet42and the reed switch43.

As seen in the schematic view inFIGS. 4A and 4B, and similar to the second example, the reed switch43of the third example includes reed elements27and28that are encapsulated within inert gas or a vacuum as they are hermetically sealed in a glass tube or chamber29. In this third example,FIG. 5shows a lowered position A of the load lift portion44, which corresponds to the position shown inFIG. 5A. This further corresponds to the schematic view seen inFIG. 4Bwhere the non-contact switch device40is in the on position, which permits an operator to raise the load lift portion44. The load lift portion44may be raised to a preselected position, such as the position B shown inFIG. 5. The raised position B inFIG. 5corresponds to the position of the non-contact switch device40shown inFIGS. 5B and 5C, where the link46has rotated sufficiently to cause the shielding member41to move to a location in the gap45between the magnet42and the reed switch43. This further corresponds to the schematic view seen inFIG. 4Awhere the non-contact switch device40is in the off position, which stops the rising load lift portion44at a preselected uppermost raised position, which represents a limit of travel.

The magnet42and reed switch43are in fixed positions with the gap45therebetween, and when the load lift portion44is in the lowered position, the non-contact switch device40normally is in a closed position because the magnet42attracts the reed element27toward and into contact with the reed elements28, as shown inFIG. 4B. When the link46rotates as the load lift portion44is raised, the shielding element41is moved to be located in the gap45between the magnet42and the reed switch43, as seen inFIG. 4A, where the reed element27returns to a pre-deflected position spaced apart from reed element28, opening the reed switch43, so as to be moved to the off position.

While this third example non-contact switch device40includes a shielding member41, it will be appreciated that the non-contact switch device40also operates in response to the presence or absence of a magnetic field between the magnet42and the reed switch43.

The above description is provided with respect to preferred examples of the non-contact switch devices for use on material handling equipment, such as pallet trucks, pallet stackers and the like. It will be appreciated, however, that the invention may be constructed and configured in various ways and is not limited to the specific examples shown and described herein, and its use is not limited to pallet trucks.

Thus, the present disclosure presents alternatives to traditional switches used on prior art material handling equipment. The non-contact switch devices provide advantageous features by permitting more compact, reliable switches that are less susceptible to wear, corrosion and issues that shorten switch service life. This results in lower costs and less downtime for maintenance or switch replacement.

It will be appreciated that the present disclosure shows and demonstrates preferred examples of non-contact switch devices for use on material handling equipment, which is discussed in the context of an example pallet truck, a pallet stacker or other material handling equipment. Indeed, these examples are merely illustrative and are not to be considered limiting. It will be apparent to those of ordinary skill in the art that the devices may be constructed and configured for use in various material handling equipment, without departing from the scope or spirit of the present disclosure. Thus, although examples non-contact switch devices have been described herein for use in a pallet truck, the scope of coverage of this patent is not limited thereto. On the contrary, this patent covers all methods, apparatus and articles of manufacture fairly falling within the scope of the appended claims either literally or under the doctrine of equivalents.