Wheelchair alarm system

Abstract

A wheelchair alarm system includes a frame adapted to be mounted beneath the wheelchair seat, an electrically operated alarm securely attached to the frame, a first switch securely attached to the frame and adapted to be maintained in contact with the wheelchair seat, and second and third switches securely attached to the frame and adapted to be positioned in the path of movement of the wheelchair brake assemblies. The alarm and the three switches are electrically connected in such a manner that the alarm is actuated if the first switch is closed and if either the second or third switch is closed, indicating that the wheelchair seat is unoccupied and at least one of the brakes is disengaged.

Description

BACKGROUND OF THE INVENTION

The present invention relates generally to an alarm system and more particularly to an alarm system for a wheelchair wherein the alarm will be activated if the wheelchair seat is unoccupied and if at least one of the wheelchair brakes is disengaged.

Most presently available wheelchairs are equipped with brake assemblies positioned on both sides of the chair. Each brake assembly includes a brake arm which is disposed to engage the adjacent drive wheel. When a patient leaves the wheelchair, he should first set the wheelchair brakes to thereby immobilize the chair and prevent it from sliding out from under him during the transfer procedure. In addition, it is most desirable that unattended wheelchairs be left with both brake assemblies engaging both drive wheels so that the chair is safely immobilized, and there will be no danger of the chair sliding out from under a patient attempting to sit in the wheelchair. In the past, as a result of the failure to engage the wheelchair brake assemblies, patients have suffered a very high incidence of injury which occurs when the chair slips from under the patient and the patient falls to the floor. Such injuries, usually in the nature of fractured hips, etc., in aged and debilitated persons are often most grave.

U.S. Pat. No. 3,302,757 discloses an apparatus designed to solve the aforementioned problems. This apparatus automatically applies a specially designed brake to each wheel of a wheelchair when weight is removed from the wheelchair seat. This apparatus utilizes an adjustable belt, upon which the patient sits, and which is connected to two spring biased brake layers to release the brake pressure when sufficient weight is applied to the belt. This apparatus is complex in structure and therefore relatively costly to manufacture and difficult to install on existing wheelchairs. In addition, this apparatus makes no provision for braking the wheelchair while the wheelchair seat is occupied.

In other environments, particularly in automotive vehicles, alarm systems have been utilized to warn the driver that the vehicle is being left in an unsafe condition. For example, U.S. Pat. No. 3,723,968 discloses an alarm circuit for an automobile which sounds an alarm if both the parking brake is off and the driver's seat is unoccupied. In addition, U.S. Pat. Nos. 3,055,187 and 3,748,640 show automobile alarm circuits responsive to both seat occupancy and other conditions in the vehicle, such as the condition of seat belts, headlights, etc.

SUMMARY OF THE INVENTION

In accordance with the present, a standard wheelchair including a seat, first and second drive wheels, and first and second drive wheel brake assemblies movable along a wheel engaging path, is provided with a frame adapted to be mounted beneath the wheelchair seat. Electrically actuated alarm means is securely attached to the frame. A first switch means is also securely attached to the frame, and is adapted to be maintained in contact with the wheelchair seat to thereby assume a first position when there is no weight on the wheelchair seat and be forced into a second position in response to a weight on the wheelchair seat. A second switch means is securely attached to the frame and is adapted to be positioned in the path of movement of the first brake assembly to thereby assume a first position when the first brake assembly is disengaged from the first drive wheel and be forced into a second position when the first brake is applied to the first drive wheel. A third switch means is securely attached to the frame and is adapted to be positioned in the path of movement of the second brake assembly to thereby assume a first position when the second brake assembly is disengaged from the second drive wheel and be forced into a second position when the second brake is applied to the second drive wheel. Conductor means are provided to electrically connect the alarm means with the first, second and third switch means so that the alarm means is actuated if the first switch means and either the second switch means or the third switch means are in the first position, indicating no weight in the wheelchair seat and the disengagement of at least one of the brake assemblies.

OBJECTS OF THE INVENTION

An object of the present invention is the provision of a wheelchair alarm system which will aid in the prevention of injury to wheelchair users.

Another object of the present invention is the provision of a wheelchair alarm system which is simple in construction and may be easily installed on existing wheelchairs.

A further object of the present invention is the provision of a wheelchair alarm system which will not interfere with the normal operation of the wheelchair or the wheelchair braking assemblies.

Still another object of the present invention is the provision of a wheelchair alarm system which is inexpensive to manufacture.

Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a front view of the wheelchair alarm system of the present invention, with the wheelchair seat shown in phantom;

FIG. 2 shows a partial top view of the wheelchair alarm system of the present invention;

FIG. 3 shows a rear view of the wheelchair alarm system of the present invention;

FIG. 4 shows an end view of the wheelchair alarm system of the present invention and shows the wheelchair brake assembly engaging the drive wheel (shown in phantom);

FIG. 5 shows an end view of the wheelchair alarm system of the present invention showing the brake assembly disengaged from the drive wheel (shown in phantom);

FIG. 6 is a schematic of the electric circuit of the wheelchair alarm system of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The structure of the wheelchair alarm system of the present invention will now be described with reference to FIGS. 1, 2 and 3. A pair of standard wheelchair brake assemblies 10 and 12 are fastened, by means of brackets 14 and 16, to structural members on the wheelchair (not shown). A wheelchair seat 18 and 18' is shown in phantom as being suspended from the same wheelchair structural member. A support means, preferably shown as a frame, generally indicated at 20, is suspended from the brackets 14 and 16 so as to be positioned beneath the wheelchair seat 18. Although the frame 20 is shown in the preferred embodiment as being suspended from the brake assemblies 10 and 12, it is to be understood that the frame 20 could be mounted beneath the wheelchair seat 18 in any known manner. The frame 20 is preferably made up of a linear main supporting member 22, which in turn includes three overlapping members 24, 26 and 28. The overlapping members are preferably formed of steel angle irons which are suitably fastened, for example, by nuts and bolts 30. Additional holes 32 may be drilled in the overlapping members so as to permit an easy adjustment in the length of the frame, to thereby permit it to be readily attached to wheelchairs of varying widths. Auxiliary supporting members 34 and 36 are securely fastened to the linear main supporting member 22 at the ends thereof, preferably by means of nuts and bolts 38. The auxiliary supporting members 34 and 36 are also preferably angle irons and are mounted at right angles with respect to the linear main supporting member 22.

An alarm means 40 is securely fastened to the center member 26, preferably by means of a bracket 42 and bolts 44. The alarm means 40 can be any electrically actuated self-contained alarm and is preferably a battery-powered commercially available unit selling under the tradename "Powerhorn Jr. Security System." This unit has its own off-on switch 46.

A plate 48 is securely fastened to the center supporting member 26, preferably by means of nuts and bolts 50. The plate includes a plurality of additional mounting holes 52 so that the position of the plate with respect to the frame 20 is adjustable. Securely fastened to the top of the plate 48 is a first switch means 54. The switch 54 is a standard microswitch having a lever 56 extending therefrom, which lever is utilized to actuate the switch 54. As is shown best in FIG. 1, the lever 56 is maintained in contact with the wheelchair seat 18, such that when the wheelchair seat is unoccupied, the seat rises somewhat (as shown at 18') and the switch lever assumes a first position as is shown in phantom in 56'. When the wheelchair seat is occupied, even a slight amount of weight on the seat 18 will be sufficient to depress the lever to a second position as is shown at 56. Thus, it is apparent that the switch means 54 can be utilized to sense whether or not the wheelchair seat is occupied.

Securely fastened to each of the auxiliary supporting members 34 and 36 are second and third switch means 58 and 60, respectively. The switches 58 and 60 include levers 62 and 64, which are positioned so as to maintain contact with the brake assemblies 10 and 12, respectively. Since the operation of the switches 58 and 60 is identical, the operation of switch 58 only will be described in connection with FIGS. 4 and 5.

In FIG. 5, the brake assembly 10 is shown disengaged from the drive wheel 66 (shown in phantom). As a result, the lever 62 of the switch 58 assumes a first position. When the brake arm 68 is applied to the wheel 66 as shown in FIG. 4, the lever 62 is forced into a second position. Thus, it is apparent that the second and third switch means 58 and 60 serve to monitor the position of the brake levers 10 and 12, respectively.

The alarm 40 and the three switches 54, 58 and 60 are electrically interconnected by suitable conductor means 70 as schematically illustrated in FIG. 6. The switch 54 includes a normally closed contact 72 and a normally open contact 74. The normally closed contact 72 corresponds to the first position of the lever 56 and thus the wiper 76 assumes contact with the normally closed contact 72 when the wheelchair seat is unoccupied. When the wheelchair seat is occupied, the weight on the seat forces the lever 56 to assume its second position and thereby forces the wiper 76 into contact with the normally open switch contact 74. When the wiper 76 is in contact with the terminal 74, it is impossible for the alarm to sound. Thus, as long as the wheelchair seat is occupied, the alarm 40 cannot be activated. The switches 58 and 60 include normally closed contacts 78 and 80, respectively, normally open contacts 82 and 84, respectively, and wipers 86 and 88, respectively. Once again, since the operation of the switches 58 and 60 is identical, the operation of switch 58 only will be described.

When the brake assembly 10 is disengaged from the drive wheel 66, the switch lever 62 assumes its first position and, as a result, the wiper 86 is in contact with the normally closed switch contact 78. When the brake 68 engages the drive wheel 66 and the switch lever 62 is forced into its second position, the wiper 86 is forced into contact with the normally open terminal 82. Thus, it can be easily seen that in order for the alarm 40 to be actuated, the switch 54 must be in the closed position, indicating that the wheelchair seat is unoccupied, and either the switch 58 or the switch 60 must also be in the closed position, indicating the brake assembly 10 or brake assembly 12 is disengaged from its respective drive wheel.

Thus, a relatively simple yet effective alarm system has been provided to aid in the prevention of injury to patients in the process of leaving or sitting in an unbraked wheelchair. The frame 20 can easily be mounted beneath the seat of any commercially available wheelchair without interfering with the normal operation of the wheelchair or the brake assemblies.

While there has been described what is at present considered to be the preferred embodiment of the invention, it will be obvious to those skilled in the art that various changes and modifications may be made therein, without departing from the invention. It is, therefore, aimed in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of the invention.

Claims

What is claimed:

1. In a wheelchair including a seat, first and second drive wheels, and first and second drive wheel brake assemblies movable along a wheel engaging path, the improvement comprising:

a. a support means adapted to be mounted beneath the wheelchair seat;

b. electrically actuated alarm means securely attached to said support means;

c. first switch means securely attached to said support means and adapted to be maintained in contact with said wheelchair seat to thereby assume a first position when there is no weight on said wheelchair seat and be forced into a second position in response to a weight on said wheelchair seat;

d. second switch means securely attached to one end of said support means and adapted to be positioned in the path of movement of said first brake assembly to thereby assume a first position when said first brake assembly is disengaged from said first drive wheel and be forced into a second position when said first brake is applied to said first drive wheel;

e. third switch means securely attached to the other end of said support means and adapted to be positioned in the path of movement of said second brake assembly to thereby assume a first position when said second brake assembly is disengaged from said second drive wheel and be forced into a second position when said second brake is applied to said second drive wheel; and

f. conductor means electrically connecting said alarm means, said first switch means, said second switch means and said third switch means so that said alarm means is actuated if said first switch means and either said second switch means or said third switch means are in said first position, indicating no weight on said wheelchair seat and the disengagement of at least one of said brake assemblies.

2. An apparatus as set forth in claim 1 wherein said support means includes a frame having a main supporting member and two auxiliary supporting members securely fastened to said main supporting member at the ends thereof.

3. An apparatus as set forth in claim 2 wherein said first switch means is securely fastened to said main supporting member and said second and third switch means are each securely fastened to one of said auxiliary supporting members.

4. An apparatus as set forth in claim 2 wherein said main supporting member is linear and includes means for adjusting the length of said main supporting member.

5. An apparatus as set forth in claim 2 wherein said frame further includes a plate having a plurality of mounting holes contained therein securely fastened to said main supporting member, and wherein said first switch means is securely attached to said plate whereby the position of said first switch means with respect to said main supporting member is adjustable.

6. An alarm system for a wheelchair having a seat and first and second brake assemblies comprising:

a. support means having a main supporting member and fastening means located at the ends of said main supporting member for attaching said support means to a wheelchair,

b. first switch means securely attached to said support means and adapted to assume a first position when unstressed and assume a second position when a force is applied to said first switch means to thereby respond to weight on said seat,

c. second switch means securely attached to one end of said support means so as to project beyond one end of said main supporting member, said second switch means being adapted to assume a first position when unstressed and assume a second position when a force is applied to said second switch means to thereby respond to the position of said first brake assembly,

d. third switch means securely attached to the other end of said support means so as to project beyond the other end of said main supporting member, said third switch means being adapted to assume a first position when unstressed and assume a second position when a force is applied to said third switch means to thereby respond to the position of said second brake assembly,

e. electrically actuated alarm means, and

f. conductor means electrically connecting said alarm means, said first switch means, said second switch means, and said third switch means so that said alarm means is actuated if said first switch means and either said second switch means or said third switch means are in said first position.

7. An alarm system as set forth in claim 6, wherein said support means further includes two auxiliary supporting members securely fastened to said main supporting member at the ends thereof.

8. An apparatus as set forth in claim 7 wherein said first switch means is securely fastened to said main supporting member and said second and third switch means are each securely fastened to one of said auxiliary supporting members.

9. An apparatus as set forth in claim 7 wherein said linear main supporting member includes means for adjusting the length of said main supporting member.

10. An apparatus as set forth in claim 7 wherein said support means further includes a plate having a plurality of mounting holes contained therein securely fastened to said main supporting member, and wherein said first switch means is securely attached to said plate whereby the position of said first switch means with respect to said main supporting member is adjustable.