Foot switch control

Abstract

A foot switch control comprising a housing, a pivoting member arranged on the housing such that the pivoting member can pivot relative to the housing about a pivot axis is provided, in which both a pair of electrical activation switches and pair of electrical safety switches are arranged inside the housing. Under normal operation only the electrical activation switches will be operated when the pivoting member is pivoted. Should however a squeezing occur, the pivoting member can be pivoted further such that a spring must be compressed before the electrical safety switches are activated. Hereby the squeezing of a person or an object can be stopped.

Description

[0001] Foot switch control

[0002] The present invention relates to a foot switch control comprising a housing, a pivoting member arranged on the housing such that the pivoting member can pivot relative to the housing about a pivot axis is provided, inside which a pair of electrical activation switches are arranged.

[0003] Electrically driven linear actuators are used in many different applications for adjusting the position of adjustable articles of furniture, including hospital beds, patient supports or the like. A common challenge when adjusting a piece of furniture either relative to the floor or relative to other parts of said piece of furniture is the risk of unintended squeezing of persons or objects.

[0004] Known methods for minimizing the risks of squeezing include safety guards or a protective construction of the adjustable piece of furniture for preventing persons or objects from entering into an unsafe area during the adjustment. A secure and protective appearance and construction of the adjustable piece of furniture is an important safety measure, it is, however, not possible to eliminate all risks of squeezing by such measures.

[0005] Further, in the event of a squeezing, it is known to provide a threshold for the maximum force applied by the motor of the actuator during adjustment of the piece of furniture. This could e.g. be done by means of a mechanical coupling disengaging when a maximum force is exceeded.

[0006] An example of an electrically driven linear actuator with a mechanical antipinch protection is known from EP2699815 to DewertOkin GmbH, which describes a coupling able to ensure that the driving connection between a spindle nut and a connecting part can be decoupled in one direction at a relatively low torque.

[0007] EP1389355 to LINAK A / S describes a method for limiting the overload of a motor by monitoring the electric current drawn by the electrical motor of the electrically driven actuator and stopping the motor of the actuator in the event of an unusually high power-consumption or an unexpected increase in the power consumption. Thus, also achieving an anti-squeeze protection, since such an increase in the power consumption could indicate the occurrence of a squeeze.

[0008] A limitation of the force is an important safety measure, which can assist in the prevention of a dangerous situation in terms of squeezing. However, although the force is limited, a person or an object can still get caught and continuously squeezed and possibly as a result be injured or damaged.

[0009] Further, it is known to equip adjustable articles of furniture, including hospital beds, patient supports or the like with squeeze protection sensors. Such sensors can e.g. be light curtains or pressure / load sensors, which detect the presence of foreign objects already present in an unsafe area or entering an unsafe area during the adjustment. The signals of the sensors are transmitted to a control unit for the actuator system, which can then activate means for stopping the operation and / or setting off an alarm. Such squeeze protection sensors are e.g. known from EP2012731 to LINAK A / S.

[0010] A common challenge with squeeze protection sensors is that they only cover a limited area and are placed where a known risk of squeezing during a certain operation is present. However, for most articles of furniture and equipment it would be expensive and often practically impossible to equip all possible unsafe areas with sensors for which reason only a few areas of potential squeezing risks are covered.

[0011] In a situation where a person is squeezed by adjustable article of furniture or a part thereof, known incidents indicate that it is quite often the same person who has unintentionally activated a foot switch of the furniture. In other incidents the initial intentional activation of the foot switch becomes unintentional once the person is squeezed. In both situations, it is difficult or even impossible for the person to deactivate the foot switch, which then only continues or increases the squeezing of the person.

[0012] The object of the invention is to provide a foot switch for overcoming the outlined problems and drawbacks.

[0013] This object is achieved by a foot switch control according to claim 1 , where it is ensured that an electrical safety switch can be activated by applying a force on the pivoting member of a magnitude which compresses the spring such it engages the free end of the tongue, which again engages and activates the electrical safety switch. The activation of the electrical safety switch can be used to interrupt the preceding activation of the activation switch. Hereby the squeezing of a person or an object can be stopped. A parallel or additional event(s) could be reversing at least a part of the activation period of the electrical activation switches or providing an alarm.

[0014] In an embodiment the spring is a flat spring, which makes it possible to design the foot switch control very compact.

[0015] In an embodiment the flat spring is fixed to the housing and a free end of the flat spring rests on the upper surface of the housing. Hereby the flat spring can displace along upper surface of the housing when the spring is compressed.

[0016] In an embodiment the displaceable free end of the tongue and the free end of the flat spring are further away from the pivot axis than their respective fixed ends. When the pivoting member is pivoted, this ensures that the electrical activation switches are activated first when the pivoting member is pivoted. This allows for a normal operation of the foot switch control, without unintentionally activating the electrical safety switches.

[0017] In an embodiment the flat spring has a raised section relative to the upper surface of the housing over the free end of the tongue. Hereby the force required compress the flat spring and thereby to bring into engagement with the tongue is increased. In addition, it also allows for a better displacement of the flat spring along the upper surface of the housing.

[0018] In an embodiment the housing comprises a cavity with an opening aligned with the activation switches and a pin arranged displaceable in the cavity, where the pivoting member, when pivoted, can activate one of the activation switches via the pin.

[0019] In an embodiment the open space in the housing created by the tongue and the opening in the cavity are closed with a resilient sealing. Hereby a closed and sealing compartment inside the housing is obtained.

[0020] In an embodiment, the upper surface of the housing comprises an arched section, where the underside of the pivoting member comprises a corresponding arched protrusion engaging the arched section, such that the pivoting member can pivot when the arched protrusion slides along the arched section. The pins are connected to each other with a flat straight spring which engages and rests on the arched section, such that the flat straight spring keeps the pivoting member in a neutral position where none of the electrical switches are activated when the pivoting member is not pivoted. Hereby it is ensured that the foot switch control is only activated when it is operated.

[0021] In an embodiment of the invention a linear actuator system comprises at least one linear electric actuator, a controller, and a foot switch control according to one or more of the above embodiments.

[0022] In an embodiment of the invention an adjustable article of furniture comprises a linear actuator system according to the embodiment just above.

[0023] The invention will be explained more fully below with reference to the embodiment shown in the accompanying drawing. In the drawing, fig. 1 shows a perspective view of a foot switch control, fig. 2 shows a first partly exploded view in perspective of the foot switch control, fig. 3 shows a second partly exploded view in perspective of the foot switch control, fig. 4 shows in perspective the underside of a pivoting member, fig. 5 shows in perspective a pin, fig. 6 shows a longitudinal cross section of the foot switch control, fig 7 shows a schematic overview of a linear actuator system, and fig. 8 shows a hospital bed comprising a linear actuator system.

[0024] The foot switch control 1 shown in fig. 1 comprises a housing 2 and a pivoting member 3 connected to the housing 2 such that the pivoting member 3 can pivot relative to the housing 2 about a pivot axis 4. Both the housing 2 and the pivoting member 3 have an oblong shape, with the pivot axis 4 running through the center of both parts’ perpendicular to the longitudinal axis of the oblong shapes of the housing 2 and the pivoting member 3.

[0025] The housing 2 forms a closed compartment having a first housing part 2a and a second housing part 2b. Inside the compartment of the housing 2, a printed circuit board 5 is arranged which comprises two pairs of electrical switches. A pair of activation switches 6a, 6b and a pair of safety switches 7a, 7b.

[0026] To guide the pivoting movement of the pivoting member 3 relative to the housing 2, the upper surface of the first housing part 2a has an arched section 8 engaging a corresponding arched protrusion 9 on the underside of the pivoting member 3. Hinged to the housing 2 along the pivot axis 4, the pivoting member 3 can pivot by sliding along the arched section 8.

[0027] The underside of the pivoting member 3 has two pairs of protrusions, a pair of protrusions 10a, 10b for engaging the activation switches 6a, 6b, and a pair of protrusions 11 a,11 b for engaging the safety switches 7a, 7b. Both pairs of protrusions and switches are arranged with one on each side of the pivot axis 4. The activation switches 6a, 6b and their corresponding protrusions 10a, 10b are arranged closest to the pivot axis 4, and the safety switches 7a, 7b and their corresponding protrusions 11 a,11 b are arranged further away from the pivot axis 4.

[0028] The upper surface of the first housing part 2a has a pair of cavities 12a, 12b on each side of the pivot axis just above the activation switches 6a, 6b. The cavities 12a, 12b are open towards the underside of the pivoting member 3 and extend from the upper surface of the first housing part 2a towards the second housing part 2b. The activation switches 6a, 6b are arranged inside the compartment of the housing 2 such that they align with the bottom of the cavities 12a, 12b. A pair of pins 13a, 13b are arranged displaceable in the cavities 12a, 12b. A hole through the bottom of the cavity 12a, 12b is closed with a resilient sealing 14a, 14b.

[0029] To engage the activation switches 6a, 6b, the pivoting member s is pivoted to either side along the arched section 8. Hereby one of the protrusions 10a, 10b is moved towards the upper surface of the first housing part 2a and engage one of the corresponding pins 13a, 13b. A continued movement will displace the pins 13a, 13b inside the cavities 12a, 12b towards the bottom of these, which again will engage one of the activation switches 6a, 6b via the resilient sealing 14a, 14b. Each of the pins 13a, 13b has knobs 15 engaging holes 16 in the side walls of the cavities 12a, 12b such that they can only be displaced or travel a certain distance inside the cavities 12a, 12b. This protects the electrical activation switches from being overloaded. The pins 13a, 13b are connected to each other with a flat straight spring 17 which engages and rests on a part of the arched section 8 on the upper surface of first housing part 2a. When the pivoting member 3 is in a position of engaging the activation switches 6a, 6b, the spring 17 is bend over the arched section 8 as the distance between the pins 13a, 13b is extended due to the displacement of either one of them. Hereby potential energy is built up in the spring 17. When the pivoting members is released, the potential energy of the spring 17 is released, bringing it into a state of equilibrium where the pivoting member 3 is in a neutral position where none of the activation switches 6a, 6b is engaged.

[0030] A part of the upper side of the first housing part 2a forms two tongues 18a, 18b having a displaceable free end aligned with the electrical safety switches 7a, 7b. The tongues 18a, 18b extends in a direction away from the pivot axis 4, such that the fixed end of the tongues 18a, 18b are closest to the pivot axis 4 and the free end furthest away from the pivot axis 4. The U-shaped open space surrounding the tongues 18a, 18b is closed with a corresponding U-shaped resilient sealing 19a, 19b allowing the free end of the tongue to be displaced.

[0031] Two springs 20a, 20b are arranged on top of the first housing part 2a, such that a part of them cover the tongues 18a, 18b, respectively. When the pivoting member 3 is pivoted to a position engaging the activation switches 6a, 6b, the pivoting member 3 can be moved further along the arched section 8. This requires, apart from the force to bend the flat straight spring 17, also that the spring 20a, 20b is compressed. This means that the protrusion 11a,11 b engages the spring 20a, 20b, which when compressed engages the tongue 18a, 18b, which again engages the safety switch 7a, 7b.

[0032] The springs 20a, 20b each have a fixed end and a free end. The fixed end 21 a, 21 b of the spring 20a, 20b has a bend portion fixed in a small cavity 22a, 22b in the first housing part 2a proximate to the fixed end of the tongue 18a, 18b. The free end 23a, 23b of the spring 20a, 20b rests on the upper side of the first housing part 2a. Along a part of the tongue 18a, 18b and over the free end of the same, the spring 20a, 20b has a raised section 24a, 24b relative to the upper surface of the first housing part 2a. When the pivoting member 3 is pivoted, the protrusion 11a,11 b engages and compresses the spring 20a, 20b such that its free end 23a, 23b slides along the upper surface of the first housing part 2a. The upper side of the first housing part 2a has a pair of projections 25a, 25b between which the free end 23a, 23b of the spring 20a, 20b is guided.

[0033] In figure 7, the foot switch 1 is seen as a part of a linear actuator system comprising electrically driven linear actuators 26,27, a control box 28, and a hand control 29. Such linear actuator systems can be configured in many ways to suit the application in which it is incorporated, typically for adjusting the position of adjustable articles of furniture, including hospital beds 30 as shown in figure 8, patient supports or the like.

Claims

Claims:

1. Foot switch control (1 ) comprising a housing (2) a pivoting member (3) arranged on the housing (2) such that the pivoting member (3) can pivot relative to the housing (2) about a pivot axis (4), the foot switch control (1) comprises two electrical activation switches (6a, 6b) arranged inside the housing (2) one on each side of the pivot axis (4), where the pivoting member (3) when pivoted can directly or indirectly activate one of the activation switches (6a, 6b), characterized in that the foot switch control (1) comprises two electrical safety switches (7a, 7b) arranged inside the housing (2) one on each side of the pivot axis (4), where the housing (2) comprises an upper surface facing the underside of the pivoting member (3), where the upper surface of the housing (2) comprises a tongue (18a, 18b) having a displaceable free end aligned with the electrical safety switches (7a, 7b) such that the displaceable free end of the tongue (18a, 18b) can be brought to engage the electrical safety switches (7a, 7b) when the pivoting member (3) is pivoted, where the control (1) comprises a spring arranged on the upper surface of the housing (2) between the tongue (18a, 18b) and the underside of the pivoting member (3), in such a manner that the spring must be compressed in order to bring the displaceable free end of the tongue (18a, 18b) to engage one of the electrical safety switches (7a, 7b), and where two electrical activation switches (6a, 6b) are arranged closer to the pivot axis (4) than the two electrical safety switches (7a, 7b) such that one of the electrical activation switches (6a, 6b) are activated prior to activating one of the electrical safety switches (7a, 7b) when the pivoting member (3) is pivoted.

2. Foot switch control (1) according to claim 1 , characterized in that the spring is a flat spring (20a, 20b).

3. Foot switch control (1 ) according to claim 2, characterized in that one end (21 a, 21 b) of the flat spring (20a, 20b) is fixed to the housing (2) and a free end (23a, 23b) of the flat spring (20a, 20b) rests on the upper surface of the housing(2).

4. Foot switch control (1) according to claim 3, characterized in that the displaceable free end of the tongue (18a, 18b) and the free end (23a, 23b) of the flat spring (20a, 20b) are further away from the pivot axis (4) than their respective fixed ends (21 a, 22b).

5. Foot switch control (1) according to claim 3, characterized in that the flat spring (20a, 20b) has a raised section (24a, 24b) relative to the upper surface of the housing (2) over the free end of the tongue (18a, 18b).

6. Foot switch control (1) according to claim 1 , characterized in that the housing (2) comprises a cavity (12a, 12b) with an opening aligned with the activation switches (6a, 6b), a pin (13a, 13b) arranged displaceable in the cavity (12a, 12b), where the pivoting member (3) when pivoted can activate one of the activation switches (6a, 6b) via the pin (13a, 13b).

7. Foot switch control (1 ) according to claim 6, characterized in that the open space in the housing (2) created by the tongue (18a, 18b) and the opening in the cavity (12a, 12b) are closed with a resilient sealing.

8. Foot switch control (1) according to claim 7, characterized in that upper surface of the housing (2) comprises an arched section (8), where the underside of the pivoting member (3) comprises a corresponding arched protrusion (9) engaging the arched section (8), such that the pivoting member(3) can pivot when the arched protrusion (9) slides along the arched section (8), and where the pins (13a, 13b) are connected to each other with a flat straight spring (17) which engages and rests on the arched section (8), and where the flat straight spring (17) keeps the pivoting member (3) in a neutrali i position where none of the electrical switches (6a, 6b, 7a, 7b) are activated when the pivoting member (3) is not pivoted.

9. A linear actuator system comprising at least one linear electric actuator (26,27), a controller (28), and a foot switch control (1 ) according to one or more of the claims 1 to 8.

10. An adjustable article of furniture comprising a linear actuator system according to claim 9.

Images