JP2746296B2 - Link structure of floor operation mechanism in bed etc. - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a floor operating mechanism, such as a bed, which can be used to improve the driving force that varies depending on the displacement of the floor when adjusting the displacement of the floor. The present invention relates to a link structure of an operation mechanism.

[0002]

2. Description of the Related Art Conventionally, floor undulating mechanisms have been widely used in beds and the like, and recently, a floor elevating mechanism in which the entire floor moves up and down has been introduced. Was. As for these mechanisms, in addition to manual mechanisms for saving labor due to labor shortage of nurses and the like in recent years, hydraulic mechanisms and electric mechanisms are becoming widespread. By the way, FIG.
As shown in the figure, a short arm 5a connected to a driving means 4 has a short arm 5a
And a link 5 (hereinafter, referred to as a high-low link 5) constituted by a long arm 5b connected to the floor and moving the floor up and down (hereinafter referred to as a high-low link 5). There is a configuration in which is raised and lowered. The short arm 5a and the long arm 5b in the high-low link 5 are usually
It is set to make a substantially right angle. Further, the high-low link 5 is provided with a biasing means (spring member) that biases the floor portion 2 to be displaced in a direction to raise the floor portion 2.

[0003]

A floor lifting mechanism 3 for raising and lowering the floor 2 using the high-low link 5 as described above.
In FIG. 5, when looking at the relationship between the load and the shaft torque, the shaft torque with respect to the load is always constant irrespective of the height. However, if a spring for urging the high / low link 5 to raise the floor 2 is provided, the shaft torque increases as the floor 2 is raised. For this reason, it is necessary to consider the standard of the mechanism itself including the driving means 4. The present invention has been proposed in view of such a background. For example, in a floor section elevating mechanism such as a bed, a shaft torque of a high-low link is suppressed from fluctuating due to a state of elevating the floor section. It is an object of the present invention to provide a link structure of a section elevating mechanism.

[0004]

To SUMMARY OF THE INVENTION To solve the problems described above, the present invention provides a floor actuating mechanism for displacing adjusting the floor of the bed or the like, and a prime mover, out of the prime mover
Screw shaft connected to force shaft, axial direction from screw shaft
And a start shaft that expands and contracts at
This link connects the drive arm and the floor
And an actuation arm connected to the actuation arm.
Move the link operating arm so that the drive shaft is biased toward the extension side.
A biasing means is provided so as to bias in a direction to rise against a load, and at least the driving arm and the operating arm are set to specific dimensions.
While, involved the displacement state of the floor portion by setting the angle between actuating arm and the drive arm is in a specific angle greater than a right angle
Instead, the link torque is substantially constant .

[0005]

When the floor is raised or lowered by applying a link having a drive arm and an operation arm with specific dimensions and an angle formed by the drive arm and the operation arm set to a specific angle exceeding a right angle, the link is used. When a spring that urges the floor is lifted, the axial torque of the link is substantially constant. Although there is some variation depending on the magnitude of the load, the variation can be suppressed as compared with the case where the current link is applied.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a link structure of a floor operating mechanism in a bed or the like according to the present invention will be described with reference to the accompanying drawings, taking an embodiment as an example. FIG. 1 schematically shows a common mechanism configuration (hereinafter, floor operation mechanism 10) of a floor elevation mechanism and a floor elevation mechanism in a bed or the like. That is, the floor operating mechanism 10 includes a motor 11 as a drive source, a screw shaft 12 connected to an output shaft of the motor 11, and a starting shaft 13 that expands and contracts in the axial direction from the screw shaft 12. Drive arm 15 of link 14 connected to
(Lf), and an operating arm 16 (Lw) connected to the floor. A spring member 17 is attached to the starting shaft 13 so as to urge the starting shaft 13 in a direction in which the starting shaft 13 extends, that is, to urge the operating arm 16 of the link 14 in the upward direction against the load. Have been. In the floor operating mechanism 10, the axial thrust of the starting shaft 13 is horizontal and the angle of the starting shaft is not considered, the load applied to the operating arm 16 of the link 14 is always vertical, and the loss in the screw shaft 12 is Other than the above shall be ignored.

Next, the floor operating mechanism 1 having the above-described configuration will be described.
0 will be described in more detail using the following symbols for convenience. That is, CL: the link length ratio Lw / Lf at the link 14, Fc: the axial thrust acting on the screw (kg
f), Fk ₀ : spring initial tension (kgf), Fk: spring force (kgf), Fs: axial thrust (kg) acting on the link 14
f), Hw: Load point height (mm), K: Spring constant (kg)
f / mm), Lk ₀ : spring degree of freedom (mm), LL ₀ : spring extension when low (mm), Lf: length of drive arm 15 (m)
m), Lw: length of working arm 16 (mm), R: shaft rotation speed (rpm), P: screw pitch (mm), Pw: shaft power (motor power) (W), T: shaft torque (kgf)・ C
m), W: Load (kgf), x: Axial displacement (mm), θ:
Moving angle (°), θ ₀ : Initial angle (°), β: Screw lead angle (°), α: Screw flank angle (°), ρ: Screw friction angle (°), γ: Crank angle (°), μ: Screw friction coefficient,
ηc: Screw efficiency

[0008] Various mechanical equations relating to the link 14 in the floor operating mechanism 10 can be expressed as follows. In this case, the axial thrust of the starting shaft 13 is horizontal. 1. Load and axial thrust Fs = CL · Cos θ / Sin (γ−θ) · W (1) When γ = 90 ° Fs = CL · W 2. Axial displacement and angle x = Lf {Cos (γ−θ) −Cos (γ−θ ₀ )} (2) 3. Load point height and angle Hw = Lw (Sin θ−Sin θ ₀ )... (3) Load height and axial displacement Hw = CL {(Sin θ−Sin θ ₀ )} / {Cos (γ−θ) −Cos (γ−θ ₀ )} x When γ = 90 ° Hw = CL · x 5. 5. Axial thrust acting on spring force and screw force Fc = Fs-Fk 6. Spring force Fk = Fk ₀ + k (LL ₀ −Lk ₀ −x)... Twice when there are two springs. Shaft torque and shaft thrust acting on screw T = Fc · P / 2πηc · 1/10

Based on the above-mentioned various dynamic calculation formulas relating to the link 14, calculations are actually made by substituting values.
It is assumed that two spring members 17 are mounted. Spring constant of spring member 17 K = 0.448 kgf / mm Initial tension of spring Fk ₀ = 38 kgf Length of operating arm 16 Lw = 250 (mm) Length of drive arm 15 Lf = 125 (mm) Load ………………………………… W = 160 (kgf) Angle formed between the drive arm 15 and the operating arm 16 of the link 14... Γ = 105 (°) of the initial operating arm 16 Angle ……………… θ ₀ = 45 (°)

In the equation (1), Cos θ / Sin (γ-θ) = Cp In the equation (2), Cos (γ-θ) -Cos (γ-θ ₀ ) = Cx In the equation (3), Sin θ−Sin θ ₀ = CH

On the basis of the above equation, when β = 30 °, C
When p, Cx and CH are obtained, The load (W) applied to the working arm 16 (Lw) is 16
FIG. 2 shows the graph assuming that the pressure is 0 kgf. From this graph, the slope of Cp and the slope Ck of the two springs are substantially parallel. Therefore, when the spring is attached, Cx- (Cp-Ck), that is, the displacement-axial thrust, in other words, the displacement-axial torque becomes horizontal, and the axial torque becomes substantially constant regardless of the axial displacement. 3).

[0012]

As described above, according to the present invention, when the floor is moved up and down by applying a link in which the angle between the drive arm and the working arm is set to an angle exceeding 90 °, the spring member is moved. When mounted, the shaft torque is substantially constant. Although there is some variation depending on the magnitude of the load, the variation can be suppressed as compared with the case where the current link is applied.

[0013]

[Brief description of the drawings]

FIG. 1 is a mechanism configuration diagram showing a schematic example in a case where a starting axis angle of a drive source is not considered in a link structure of a floor operating mechanism in a bed or the like according to the present invention.

FIG. 2 is a graph for explaining the operation of the link structure of the floor operating mechanism in a bed or the like according to the present invention.

FIG. 3 is a graph showing a relationship between shaft displacement and shaft torque by a link structure of a floor operating mechanism in a bed or the like according to the present invention.

FIG. 4 is an overall schematic explanatory view showing an example of a floor elevating mechanism in a bed or the like to which a current link structure is applied.

FIG. 5 is a graph showing a relationship between shaft displacement and shaft torque based on a current link structure.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Floor operation mechanism 11 Motor 12 Screw shaft 13 Starting axis 14 Link 15 Drive arm 16 Operating arm 17 Spring member

Claims (1)

(57) [Claims] A floor operating mechanism for adjusting the displacement of a floor of a bed or the like, comprising a motor and an output of the motor.
Screw shaft connected to shaft, axially from screw shaft
A telescopic starting shaft, and a link at the tip of the starting shaft
Connect the floor with the drive arm and the floor side
And an actuation arm that is actuated.
Load the link operating arm so that the shaft is urged toward the extension side.
A biasing means is provided so as to bias in the upward direction against the weight, and at least the drive arm and the operating arm are set to a specific size.
While, involved the displacement state of the floor portion by setting the angle between actuating arm and the drive arm is in a specific angle greater than a right angle
A link structure of a floor operating mechanism in a bed or the like , wherein the shaft torque of the link is substantially constant .