CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a U.S. National Phase of International Patent Application Serial No. PCT/EP2018/052439 entitled “BISTABLE HOISTING SOLENOID,” filed on Jan. 31, 2018. International Patent Application Serial No. PCT/EP2018/052439 claims priority to German Patent Application No. 10 2017 000 901.5 filed on Feb. 1, 2017. The entire contents of each of the above-referenced applications are hereby incorporated by reference for all purposes.

TECHNICAL FIELD

The present invention relates to a bistable lifting solenoid that has a first and a second end of stroke position.

BACKGROUND AND SUMMARY

A bistable lifting solenoid is known from WO 2015/058742 A2 that a stator, one or more armatures, at least one coil, at least one permanent magnet, and a spring system having a first spring that exerts a force on the armature or armatures in the direction toward an end of stroke position in the first end of stroke position and having a second spring that externs a force on the armature or armatures in the direction toward the center of stroke position in the second end of stroke position, wherein the armature or armatures are held in a permanent magnetic manner against the spring force in both end positions in the currentless case. The spring system permits a particularly efficient operation of the lifting solenoid.

Further bistable lifting solenoids having spring systems are known from the documents US 2006/231050 A1 and U.S. Pat. No. 4,829,947 A.

It is the object of the present invention to provide an improved bistable lifting solenoid.

This object is inter alia achieved in a first aspect by a bistable lifting solenoid in accordance with the disclosure.

The present invention comprises lifting solenoids that are respectively bistable independently of one another in accordance with a plurality of aspects described in more detail in the following.

The lifting solenoids each have a first end of stroke position and a second end of stroke position. The lifting solenoids comprise a stator, one or more armatures, at least one coil, and at least one permanent magnet, wherein the armature or armatures are held in a permanent magnetic manner in both end of stroke positions in the currentless case. The lifting solenoids preferably each have a spring system having a first spring that exerts a force on the armature or armatures in the direction toward a center of stroke position in the first end of stroke position and having a second spring that externs a force on the armature or armatures in the direction toward a center of stroke position in the second end of stroke position, wherein the armature or armatures are held in a permanent magnetic manner against the spring force in both end of stroke positions in the currentless case. The lifting solenoids preferably have two coils.

The individual aspects of the present invention will now be shown in more detail. If not otherwise stated, preferred embodiments and possible embodiments each relate to all the independent aspects.

In a first aspect, the present invention comprises a bistable lifting solenoid that has a first end of stroke position and a second end of stroke position. The bistable lifting solenoid comprises a stator, one or more armatures, at least one coil, at least one permanent magnet, and a spring system having a first spring that exerts a force on the armature or armatures in the direction toward a center of stroke position in the first end of stroke position and having a second spring that externs a force on the armature or armatures in the direction toward a center of stroke position in the second end of stroke position, wherein the armature or armatures are held in a permanent magnetic manner against the spring force in both end of stroke positions in the currentless case. Provision is made in accordance with the invention in accordance with the first aspect that the first and second springs have spring travels of different lengths and/or exert forces of different strengths on the armature or armatures and/or have spring rates of different amounts in the respective end of stroke position. A variety of design advantages result from the different springs.

For example, the lifting solenoid can be configured such that it is moved with a greater force and/or at a greater acceleration from one of the two end of stroke positions in the direction toward the center of stroke position than from the other end of stroke position. This is of advantage in a number of applications.

The spring travel of the first spring is preferably greater than the spring travel of the second spring and the second spring exerts a greater force on the armature or armatures in the second end of stroke position than the first spring exerts on the armature or armatures in the first end of stroke position.

Alternatively or additionally, the spring travel of the first spring can be greater than the spring travel of the second spring and the spring rate of the second spring in the second end of stroke position can be greater than the spring rate of the first spring in the first end of stroke position.

In a possible embodiment of the present invention, the spring travel of the first spring amounts to between twice and 100 times the spring travel of the second spring, preferably between 4 times and 20 times.

In a further possible embodiment of the present invention, the force the second spring exerts on the armature or armatures in the second end of stroke position amounts to between 1.5 times and 100 times the force the first spring exerts on the armature or armatures in the first end of stroke position, preferably between 3 times and 15 times.

In a further possible embodiment of the present invention, the spring rate of the second spring in the second end of stroke position amounts to between twice and 1000 times the spring rate of the first spring in the first end of stroke position, preferably between 10 times and 500 times, further preferably between 20 times and 100 times.

The two springs can have a spring rate constant over the spring travel or can have a spring rate asymmetrical over the spring travel.

In accordance with a further aspect of the present invention that is preferably combined with the first aspect, at least one of the springs, and preferably the second spring, does not generate any force between the armature and the stator over a part of the stroke distance and/or is not in contact with the armature and/or with the stator over a part of the stroke distance.

A retention security is preferably provided in this case that secures the spring in a predetermined position over this part of the stroke distance and in so doing preferably holds it in a preloaded state.

In a preferred embodiment, the bistable lifting solenoid has an asymmetrical characteristic. The movement from the first end of stroke position into the second end of stroke position in particular differs with the same supply of current to the coil, in particular with respect to the progression of the force and/or speed of the lifting solenoid.

Provision is made in a possible embodiment that the magnetic holding force of the lifting solenoid is smaller in one of the two end of stroke positions than in the other end of stroke position. The magnetic holding force of the lifting solenoid can in particular be at least 20% smaller in one of the two end of stroke positions, further preferably at least 30% smaller than in the other end of stroke position.

The magnetic holding force in the first end of stroke position is preferably smaller than in the second end of stroke position.

Alternatively or additionally, the magnetic holding force in one of the end of stroke positions can amount to at least 20% of the magnetic holding force in the other end of stroke position, preferably at least 30%.

Provision is made in a possible embodiment that the stator and the armature or armatures have a geometrical characteristic influence in one of the end of stroke positions, and preferably in the first end of stroke position, in particular a working air gap, in particular a conically extending working air gap, not extending in a plane perpendicular to the axle of the lifting solenoid.

The stator and the armature or armatures preferably have a weaker or no geometrical characteristic influence in the other end of stroke position, and preferably in the second end of stroke position.

Provision is made in a possible embodiment that the difference between the amount of the magnetic holding force and the amount of the force that the respective spring applies differs by a maximum of 50% of the larger value in both end of stroke positions.

In accordance with a further aspect of the present invention, the lifting solenoid has a resting point in a position between the two end of stroke positions in the currentless case. It is here a third stroke position of the lifting solenoid that is stable in the currentless case. This aspect is preferably combined with the first aspect.

Provision is made in a possible embodiment that the resting point is offset with respect to the center of the travel distance, with the resting point preferably being arranged between one of the end of stroke positions, in particular the second end of stroke position, and the center of the stroke distance.

The distance between the resting point and the center of the stroke distance preferably amounts to more than 5% of the stroke distance, further preferably more than 10%, further preferably more than 20%.

Alternatively or additionally, the distance between the resting point and the one end of stroke position from which it has the smaller distance, in particular from the second end of stroke position, amounts to more than 2% of the stroke distance, further preferably more than 5%, further preferably more than 10%.

In accordance with a further aspect of the present invention, the potential energy, excluding the electrical energy and in the currentless case, stored in the two end of stroke positions of the lifting solenoid, does not differ by more than 50% of the greater value, preferably by no more than 25%. A particularly energy saving operation of the lifting solenoid hereby becomes possible.

Some design features of the lifting solenoid will be described in the following that can be implemented both individually and in combination, and indeed in all of the above-described aspects and in the still following aspects.

Provision is made in a possible embodiment that the at least one coil and the at least one permanent magnet are arranged at the stator.

Provision is made in a possible embodiment that the stator forms a housing that surrounds the armature or armatures, with an armature preferably being provided that is arranged in the interior of the stator on a guide rod, with the guide rod preferably being movably supported at the stator.

Provision is made in a possible embodiment that the spring system is arranged within the stator, with the first spring preferably being arranged between the first front section and a first side of the armature and the second spring being arranged between a second front section and a second side of the armature, and/or with the first and second springs being configured as coil springs that encompass the guide rod of the armature.

Provision is made in a possible embodiment that the stator has a soft magnetic sleeve and first and second soft magnetic front sections that form a housing in which the armature is displaceably arranged.

In a possible embodiment, at least one first working air gap can be provided between the armature and the first front section and at least one second working air gap can be provided between the armature and the second front section.

At least one permanent magnet and at least one first coil and one second coil are preferably arranged at the stator, with the armature forming a first magnetic part circuit with the sleeve and the first front section in the first end of stroke position, said first magnetic part circuit surrounding at least the first coil, while the working air gap or gaps are opened to a maximum with the second front section, and with the armature forming a second magnetic part circuit with the sleeve and the second front section in the second end of stroke position, said second magnetic part circuit surrounding at least the second coil, while the working air gap or gaps are opened to the maximum with the first front section.

Provision is made in a possible embodiment that the at least one permanent magnet is arranged between the first and second coils in an axial direction and forms a respective part of the first and second magnetic part circuits, with the permanent magnet being arranged such that it overlaps the armature both in the first end of stroke position and in the second end of stroke position in the axial direction and preferably surrounds it, with the permanent magnet preferably being directly magnetically coupled to the armature. Different arrangements of the permanent magnet or permanent magnets are, however, also possible.

In a second aspect, the present invention comprises a bistable lifting solenoid that has a first end of stroke position and a second end of stroke position. The lifting solenoid comprises a stator, one or more armatures, at least one coil, and at least one permanent magnet, wherein the armature or armatures are held in a permanent magnetic manner in both end of stroke positions in the currentless case. The stator has a soft magnetic sleeve and a first soft magnetic end section and a second soft magnetic end section that form a housing in which the armature is displaceably arranged, with at least one first working air gap being provided between the armature and the first front section and with at least one second working air gap being provided between the armature and the second front section. At least one permanent magnet and at least one first coil and one second coil are arranged at the stator, with the armature forming a first magnetic part circuit with the sleeve and the first front section in the first end of stroke position, said first magnetic part circuit surrounding at least the first coil, while the working air gap or gaps are opened to a maximum with the second front section, and with the armature forming a second magnetic part circuit with the sleeve and the second front section in the second end of stroke position, said second magnetic part circuit surrounding at least the second coil, while the working air gap or gaps are opened to the maximum with the first front section. The lifting solenoid in accordance with the first aspect is characterized in that at least one first permanent magnet and one second permanent magnet are provided, wherein the first and second coils are arranged between the first and second permanent magnets in the axial direction, with the first permanent magnet putting the sleeve and the first front section under a magnetic voltage and the second permanent magnet putting the sleeve and the second front section under a magnetic voltage.

The construction length can hereby be reduced with respect to other design embodiments.

Provision is made in a possible embodiment that the first magnetic part circuit encompasses the first permanent magnet and the second magnetic part circuit encompasses the second permanent magnet.

Provision is made in a possible embodiment that the armature magnetically short circuits the sleeve and the first front section in the first end of stroke position and that the armature magnetically short circuits the sleeve and the second front section in the second end of stroke position.

Provision is made in a possible embodiment that the sleeve has a magnetic circuit section between the two coils that overlaps the armature in both the first end of stroke position and in the second end of stroke position in the axial direction and that preferably surrounds it, with the magnetic circuit section preferably magnetically directly coupling at the armature.

Provision is made in a possible embodiment that the first and second coils are arranged at least partly between the sleeve and the movement range of the armature and/or in an inner groove and/or cutout of the sleeve.

The lifting solenoid preferably further has a spring system having a first spring that exerts a force on the armature or armatures in the direction toward a center of stroke position in the first end of stroke position and having a second spring that externs a force on the armature or armatures in the direction toward a center of stroke position in the second end of stroke position, wherein the armature or armatures are held in a permanent magnetic manner against the spring force in the first and second end of stroke positions in the currentless case.

Provision is made in accordance with a further aspect of the present invention that is preferably combined with the second aspect that the first and/or second front section(s) has/have a fastening region that extends beyond the first and/or second permanent magnet(s) in the radial direction and is/are fastened to the sleeve. The assembly is hereby substantially simplified.

The fastening region is preferably magnetically saturated by the first or second permanent magnet.

In a possible embodiment, the fastening region is of board-shape, in particular of an annular board shape, and/or has cutouts.

In a possible embodiment, the fastening region has less material toward the outside and in particular becomes thinner.

The above-described aspects of the present invention can be implemented independently of one another. Two or more of the above-described aspects of the present invention are, however, preferably implemented in combination, in particular the first and second aspects in combination.

In a third independent aspect, the present invention comprises a control for a lifting solenoid in accordance with the invention having one or more electrical energy stores, in particular capacitors, and having a control that discharges the energy store or stores via the at least one coil of the lifting solenoid with the aid of switches, in particular semiconductor switches, such that the lifting solenoid is moved from one end of stroke position into the other end of stroke position. High adjustment forces and/or accelerations can hereby nevertheless be achieved with a relatively low current consumption.

Provision is made in a possible embodiment that the control recognizes an interruption and/or a switching off of a voltage supply and moves the lifting solenoid in response thereto, in particular from the first end of stroke position into the second end of stroke position, with the dropping of the supply voltage preferably being recognized by means of a flank recognition. A lifting solenoid equipped with this control can hereby be used instead of a monostable lifting solenoid or of a monostable pneumatic drive.

In a possible embodiment, the control is configured such that in response to a switching on of the supply voltage, the electrical energy store or stores, preferably capacitor(s), is/are charged and such that the reaching of a specific threshold voltage at the electrical store is recognized by the control, whereupon the latter discharges the energy store or stores via the bistable lifting solenoid so that it moves in the opposite direction, in particular into the first end of stroke position.

Provision is made in a possible embodiment that the bistable lifting solenoid is controlled by a full bridge, in particular by a MOSFET full bridge.

In a preferred embodiment, the circuit has two further semiconductor switches via which a first energy store and a second energy store can be connected in parallel in a first switching state and can be separately discharged in a second switching state.

The control can furthermore comprise means for position detection of the stopper, with the control preferably having a microcontroller that is connected to the means for position detection and that takes account of the location information acquired by means of the means for position detection on the control of the bistable lifting solenoid.

In accordance with a further preferred aspect, the control has at least one first energy store and one second energy store, with the first energy store being able to be discharged in series b< two coils of the lifting solenoid, and with the second energy store being able to be discharged by only one of the two coils of the lifting solenoid.

In a possible embodiment, the second energy store is selectively able to be discharged by one of the two coils. The discharge can here in particular take place by the first coil or by the second coil in dependence on the direction of movement.

Alternatively or additionally, the second energy store can selectively also be able to be discharged in series by the two coils of the lifting solenoid. The discharge can here in particular take place by one of the two coils or in series by the two coils in dependence on the direction of movement.

The control is in particular designed such that, for a control of a first direction of movement of the lifting solenoid, in particular of from the first end of stroke position into the second end of stroke position, both energy stores are discharged in series by two coils of the lifting solenoid and, for a control of a second direction of movement of the lifting solenoid, in particular from the second end of stroke position into the first end of stroke position, the first energy store is discharged in series by the two coils and the second energy store is discharged by only one of the two coils, in particular by the first coil.

The discharge of the second energy store particularly preferably takes place with a time lag to the discharge of the first energy store, with the discharge of the second energy store preferably starting even before the occurrence of the adjustment process.

The control described in more detail above in accordance with the third aspect of the present invention is also a subject of the present invention independently of the specific embodiment of the lifting solenoid.

The control is preferably used with a lifting solenoid that has two coils that are connected in series and that preferably have a central tapping.

The control in particular takes place such that both energy stores are discharged by the coils connected in series along a first direction of movement, in particular along a direction of movement from the first end of stroke position into the second end of stroke position, while on the opposite direction of movement, in particular a movement from the second end of stroke position into the first end of stroke position, the first energy store is first discharged by the coils connected in series and the second energy store is discharged with a time delay by the central tapping of both coils, with the discharge of the second energy store preferably starting even before the occurrence of the adjustment process.

The control in accordance with the invention is particularly preferably used in accordance with the third aspect with a lifting solenoid such as was described in more detail above, in particular with a lifting solenoid in accordance with one of the aspects described in more detail above and/or with the preferred design embodiment described in more detail above.

The present invention will now be described in more detail with reference to embodiments and drawings.

