JP2002308600A - Table lift - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve starting performance by increasing a starting torque when a table is lifted and decreasing the torque when the table is lowered. SOLUTION: This table lift 1 comprises a base part frame 2, the table 3 arranged above the base part frame, connecting means 4 for connecting the base part frame and the table such that both are vertically liftable, a rack 5 extending to the lifting direction of the table and standingly mounted on the base part frame, and guide means 6 having a motor 7 comprising a pinion 7a to be engaged with the rack and upper and lower limiters 8, 9 for obtaining a positioning signal in the lifting direction of the table and to be arranged on the table. The motor 7 is a capacitor induction motor, and capacity of the capacitor to be connected to winding changes according to the lifting and lowering directions of the table and is large when the table is lifted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a table lift which raises and lowers a table on which a wheelchair or the like is placed, and which can move the wheelchair or the like even where there is a step.

[0002]

2. Description of the Related Art A table lift of this type includes a base frame, a table disposed above the base frame, connecting means for connecting the base frame to the base frame so that the table can be moved up and down. Generally, a driving means for raising and lowering the table is used as a constituent member. A scissor link composed of two link levers is used as the connecting means. Also, as the driving means,
Using a hydraulic cylinder (Japanese Unexamined Patent Publication No. 7-255781,
Japanese Patent Application Laid-Open No. 9-290995) and those using an electric motor (Japanese Utility Model Application Laid-Open No. 2-68826).

The inventor of the present application has developed a table lift of a type using an electric motor as a driving means. The basic structure of the table lift is different from that shown in the Japanese Utility Model Laid-Open No. 2-68826. That is, in the conventional one, an electric motor is fixed to a base frame, a screw shaft is provided on the electric motor, and a nut is screwed on the table with a screw shaft. The table is raised and lowered by rotating the screw shaft forward and reverse. . In this case, since the screw shaft has a length corresponding to the elevating stroke and rotates forward and backward, high-precision machining of the screw shaft is troublesome or requires a considerable strength of the screw shaft. On the other hand, the inventor of the present application sets up a rack extending in the elevating direction of the table on the base frame, and obtains a capacitor induction motor having a pinion meshing with the rack on the table and a positioning signal in the elevating direction of the table. Guide means having upper and lower limiters for the movement.

[0004]

In the above-described motor, since only a pinion, which is a general spur gear, is provided in the electric motor, if only the rack is manufactured with required strength,
When manufacturing the electric motor, it is not necessary to secure the trouble and strength as in the conventional motor. By the way, a capacitor induction motor is provided with an auxiliary winding at a position at an electrical angle of 90 ° with respect to a main winding, and a capacitor connected in series to the auxiliary winding, thereby generating a rotating magnetic field to generate torque. Since the power factor during operation is good, it is widely used with an output of less than 400 W. When this capacitor induction motor is used for a table lift, a wheelchair or the like is mounted on the table lift, so that it is desirable to increase the starting torque in the ascending direction as much as possible. To increase the starting torque, there is a method of increasing the capacity of a capacitor connected in series to the auxiliary winding. However, when the starting torque in the ascending direction is increased, in the operation at the time of starting in the descending direction, the weight of the wheelchair or the like acts on the side that increases the starting torque, and thus the vehicle may suddenly start.

The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to increase the starting torque in the upward direction of the table and to reduce the starting torque in the downward direction of the table to reduce the starting performance in the up-and-down operation. To provide an improved table lift.

[0006]

According to a first aspect of the present invention, there is provided a table lift, comprising: a base frame; a table disposed above the base frame; Means for connecting the two so as to be able to move up and down, a rack extending in the elevating direction of the table and standing upright on the base frame, and a motor having a pinion meshing with the rack and a positioning signal in the elevating direction of the table are obtained. And a guide means disposed on the table having upper and lower limiters for driving the motor, wherein the motor is a capacitor induction motor, and the capacity of a capacitor connected to the winding is increased and lowered by the table. It is configured to change according to the direction, and to increase the capacity in the ascending direction.

According to a second aspect of the present invention, the capacitor connected to the winding according to the first aspect includes a first capacitor and a second capacitor.
And the second capacitor is connected in parallel to the first capacitor only in the descending direction.

According to a third aspect of the present invention, in the table lift according to the second aspect, the second capacitor has a larger capacity than the first capacitor.

According to a fourth aspect of the present invention, the first and second capacitors according to the second and third aspects are configured to be switched in response to a relay contact that determines a direction of elevating the table.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a front view showing a state where a table is at an upper stop position, FIG. 2 is a plan view of an operation box, and FIG.
4 is a side view showing the state of the connecting means when the table is at the upper stop position, FIG. 4 is a side view when the table is also at the lower stop position, FIG. 5 is a front view of the guide means, and FIG. 6 is a side view of the guide means. 7, FIG. 7 is a circuit diagram of a 100V system mainly composed of windings of the motor, FIG. 8 is a circuit diagram of a low voltage system mainly composed of a relay control system, FIG. 9 is a torque curve of the motor when ascending, and FIG. 6 is a torque curve of the electric motor at the time.

The table lift 1 of the present invention comprises a base frame 2, a table 3, connecting means 4 for connecting the base frame 2 to the table 3, a rack 5 erected on the base frame 2, an electric motor 7, and upper and lower limiters 8. , 9 provided on the table 3 and the control circuit 15
(100V system circuit 15A and low voltage system circuit 15B) and the like are main components.

The base frame 2 has a frame shape made of iron or aluminum, and each side of the frame shape is, for example, about 100 cm. The table 3 is a member that is disposed above the base frame 2 and on which a wheelchair or the like is placed. . Further, a part of the flat plate portion has an opening through which a rack 5 and a guide means 6 described later can penetrate. In this example, the weight is about 30 to 40 kg. The table 3 is connected to the base frame 2 by connecting means 4 described below so that the table 3 can be moved up and down with respect to the base frame 2. A bellows-shaped sheet S is suspended from the table 3 and covers an inner member.

As shown in FIG. 3, the connecting means 4 uses two X-shaped scissor links L composed of two link levers 4a and 4b. Since FIG. 3 is a side view, only one scissor link L is visible. The scissor link L is a general one. The center of the link levers 4a and 4b in the longitudinal direction is rotatably connected by a shaft 4c, and one ends 4d and 4e of the link levers 4a and 4b are connected to the base frame 2 and the table. 3 so as to be rotatable, and both link levers 4a,
The other end 4f, 4g of 4b is slidably fixed to the table 3 and the base frame 2. Therefore, when the table 3 is at the lowermost position, the two link levers 4a and 4b are folded so as to be almost within the height of the base frame 2, as shown in FIG.

As shown in FIG. 5, the rack 5 has a long rectangular column shape as a whole, and a tooth portion 5a is engraved on one surface in the longitudinal direction, and the other three surfaces 5b, 5c, and 5d are flat. After being finished, the table 3 is erected on the base frame 2 so as to extend in the vertical direction. Even when the table 3 is at the upper limit position (for example, about 70 cm from the floor), it has a length (for example, about 30 cm from the table 3) that protrudes sufficiently from the table 3 and is formed of iron or aluminum. .

As shown in FIGS. 5 and 6, the guide means 6 includes an electric motor 7 having a pinion 7a that meshes with the teeth 5a of the rack 5, and an upper and lower motor for obtaining a positioning signal for moving the table 3 up and down. It is disposed on the table 3 with the lower limiters 8 and 9. That is, the guide means 6 fixes the support plates 6a, 6a to the table 3 at predetermined intervals so as to sandwich the rack 5, and attaches the electric motor 7 and the upper and lower limiters 8, 9 to these. The motor 7 is a capacitor induction motor in which an auxiliary winding is provided at a position at an electrical angle of 90 ° with respect to the main winding, and a capacitor is connected to the auxiliary winding in series.
In this example, 100 W is used. Further, the electric motor 7 also has a brake applying function. Then, through an appropriate reduction gear train, for example, the pinion 7a
(Pinion shaft 7b) has a rotation speed of about 7 rpm.
Then, the pinion shaft 7b is supported by the support plates 6a, 6a so that the pinion 7a meshes with the teeth 5a of the rack 5. At this time, the support plates 6a, 6c, 6c, 6c, 6c, 6c, 6c, 6c, 6c, 6c, 6c, 6c, 6c, 6c, 6c, 6c, 6c, 6c, 6c, 6c, 6c, 6c, 6c, 6c
6a. The slide collar 6d and the slide plate 6e are interposed between the other surfaces 5c and 5d of the rack 5 and the support plates 6a and 6a. With these configurations, the guide means 6, that is, the table 3, reliably responds to the rotation of the pinion 7 a, and the table 3 can be prevented from swinging. The upper and lower limiters 8 and 9 are limit switches using an actuator for the detection unit.

Reference numerals 11 and 12 denote upper and lower contact plates, respectively.
It is a member for giving a positioning signal to the upper and lower limiters 8 and 9, and is provided on a member that does not perform a vertical movement. In this example, the upper contact plate 11 is adjusted so that the rack 5 can be adjusted.
The lower contact plate 12 is fixed to the base frame 2. Therefore, the upper contact plate 11 is used to
1a, a fixing screw 11b screwed to one piece of the base 11a,
An abutment portion 11c abuts on an actuator of an upper limiter 8 provided at an upper end of the base 11a.
By screwing 1b, its tip abuts on the surface 5b on the opposite side of the tooth portion 5a of the rack 5, pulls the entire base 11a toward the fixing screw 11b, and one of the opposing pieces into which the fixing screw 11b is screwed is formed. The tooth portion 5a is pressed and fixed.

Reference numeral 13 denotes an operation box, which covers the rack 5, the guide means 6, and a control circuit section 15 which will be described later, and has operation buttons 13a and 13b at an upper portion and an adjustment window 13c at the front. The operation buttons 13a and 13b are operation buttons for ascending and descending, but at least these are necessary. The adjustment work window 13c is openable and closable, and is opened to rotate the fixing screw 11b of the upper contact plate 11. Reference numeral 14 denotes a power supply line connected to a commercial power supply.

Next, the control circuit unit 1 will be described with reference to FIGS.
Circuit 5 will be described. FIG. 7 is a circuit 15A of a 100V system mainly composed of windings and brake operating members, and FIG. 8 is a circuit 15A of a low voltage system mainly composed of sequence control by many relays.
B. The control circuit unit 15 is mounted as an appropriate circuit block, and is fixed to the table 3 while being covered with the operation box 13. The electric motor 7 has a main winding 7m and an auxiliary winding 7s. The second winding Cs is connected to the auxiliary winding 7s via a first capacitor C1 and a relay contact. Control. In this example, the first capacitor C1 is 15 μF, and the second capacitor is 30 μF. Hereinafter, the connection relation will be described based on the sequence operation.

When the ascending operation button 13a is pressed, the relay Rp is excited, the contact Rp is turned on, and the relays R11 and R1 are turned on.
2, R13 are excited and their contacts R11, R12, R1
Turn 3 on. As a result, the first and second capacitors C1 and C2 are connected to the auxiliary winding 7s in a parallel relationship, and power is supplied to both the windings 7m and 7s, thereby releasing the brake operating portion B. Therefore, the electric motor 7 rotates by generating a predetermined starting torque under a predetermined rotating magnetic field, and the table 3 moves up. Then, the upper limiter 8 is connected to the upper contact plate 1.
When it comes into contact with 1 and reverses, this becomes the positioning signal,
Excitation of relay Ro, contact Ro off, relay R1
1, demagnetize R12, R13, their contacts R11, R1
2. Turn off R13. Thereby, both windings 7m, 7m
The power supply to s is stopped, and the brake operating unit B is operated.
Accordingly, the electric motor 7 is in a state where a predetermined braking force is applied, and the table 3 stops at the predetermined upper stop position.

When the descending operation button 13b is pressed while the table 3 is stopped at the predetermined upper stop position, the relay Rq
, The contact Rq is turned on, the relays R21 and R22 are excited, and the contacts R21 and R22 are turned on. As a result, since the contact R12 is off, the auxiliary winding 7s is connected to only the first capacitor C1 and both windings
Electric current is applied to m and 7s so as to obtain a rotating magnetic field in a direction opposite to that in the ascending state, and the brake operating portion B is opened. Accordingly, the electric motor 7 generates a smaller starting torque than when the motor 7 rises, rotates in the opposite direction, and the table 3 descends. And
When the lower limiter 9 abuts on the lower abutment plate 12 and reverses, this becomes a positioning signal, demagnetizes the relays R21 and R22, and turns off the contacts R21 and R22. As a result, the power supply to both windings 7a and 7b is stopped, and the brake operating section B is operated. Accordingly, the electric motor 7 is in a state where a predetermined braking force is applied, and the table 3 stops at the lower stop position.

That is, the capacity of the capacitor connected to the winding of the electric motor 7 is changed in accordance with the direction in which the table 3 is raised and lowered, and the capacity in the upward direction is large. More specifically, the capacitor connected to the winding (auxiliary winding 7s) is composed of a first capacitor C1 and a second capacitor C2, and the first and second capacitors are connected in parallel when rising. The first capacitor C in the descending direction
Only one is connected. Further, the capacity of the second capacitor C2 is larger than that of the first capacitor C1. The connection between the first and second capacitors C1 and C2 is switched in response to a relay contact that determines the direction in which the table 3 is moved up and down.

The torque curve of the electric motor 7 in the above operation is as follows. When the table 3 is moving in the upward direction, that is, when a load is applied to the electric motor 7, the first
Since the second capacitor C1 and the second capacitor C2 are connected in parallel and the capacitor capacity is large (45 μF), as shown in FIG. The starting torque increased to 122%. When the table 3 is moving downward, that is, when the load contributes to the starting torque for the electric motor 7, only the first capacitor C1 is connected and the capacitor capacity is small (15 μF). In addition, assuming that the starting in a state where the capacitor capacity is large as described above is 100%, in the case of the present invention, the starting torque could be reduced to 50%.

Although the main part of the embodiment of the present invention has been described above, the table lift 1 raises and lowers a table on which a wheelchair or the like is mounted, and can move the wheelchair or the like even in a place having a step. At the left and right ends of the table 3 in FIG. 1, a bridge plate for bridging the raised table 3 and the entrance frame, and a slope plate for mounting a wheelchair or the like on the table 3 from the floor surface are appropriately rotatably provided. Attach (not shown). Further, the illustrated numerical values are not limited thereto, and various modifications are possible within the scope of the technical idea described in the claims.

[0024]

In the table lift according to the present invention, the capacity of the capacitor connected to the winding of the capacitor induction motor changes in accordance with the direction in which the table is raised and lowered, and the capacity in the upward direction is increased. Therefore, when the table is in the upward direction, that is, when the starting torque is required, it is large, and when the table is in the downward direction, that is, when the starting torque is not so necessary or large, it is possible to reduce the possibility of performing a sudden operation. In addition, the starting performance in the elevating operation can be improved.

[Brief description of the drawings]

FIG. 1 is an overall front view showing an embodiment of the present invention.

FIG. 2 is a plan view of the operation box according to the first embodiment.

FIG. 3 is a side view showing a state of the connecting means when the connecting means is at an upper stop position.

FIG. 4 is a side view showing a state of the connecting means when the connecting means is at a lower stop position according to the first embodiment;

FIG. 5 is a front view of the same guide means.

FIG. 6 is a side view of the same guide means.

FIG. 7 is a circuit diagram of a 100 V system mainly including windings of the electric motor.

FIG. 8 is a circuit diagram of a low-voltage system mainly including the relay control system according to the first embodiment.

FIG. 9 is a torque curve of the electric motor at the time of ascending;

FIG. 10 is a torque curve of the electric motor at the time of descending according to the embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Table lift 2 Base frame 3 Table 4 Connecting means 5 Rack 5a Rack tooth 6 Guide means 7 Electric motor 7a Pinion of electric motor 7m Main winding of electric motor 7s Auxiliary winding of electric motor 8 Upper limiter 9 Lower limiter 11 Upper contact plate 12 Lower contact plate 13 Operation box 15 Control circuit unit 15A 100V system circuit 15B Low voltage system circuit C1 First capacitor C2 Second capacitor B Brake operation unit

Claims (4)

[Claims] 1. A base frame, a table disposed above the base frame, connecting means for connecting the base frame to the base frame so that the table can be moved up and down, and a table extending in the table elevating direction. A rack erected on the base frame, guide means disposed on the table having an electric motor having a pinion meshing with the rack, and upper and lower limiters for obtaining a positioning signal in the elevating direction of the table, Wherein the motor is a capacitor induction motor, the capacity of the capacitor connected to the windings changes according to the direction in which the table is raised and lowered, and the capacity in the upward direction is increased. A table lift characterized by the following. 2. A capacitor connected to the winding comprises a first capacitor and a second capacitor, wherein the first and second capacitors are arranged in parallel in the rising direction and the first capacitor in the falling direction. The table lift according to claim 1, wherein the table lift is connected only to the table lift. 3. The table lift according to claim 2, wherein the second capacitor has a larger capacity than the first capacitor. 4. The table lift according to claim 2, wherein the first and second condensers are switched in response to a relay contact that determines a direction in which the table is moved up and down.