JPS5910972Y2 - Spring balance mechanism - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a pantograph type spring balance mechanism.

As a specific publicly known technology of a device for supporting and stabilizing an object by generally obtaining mechanical equilibrium,
There is a No. 33 force balance device.

This force balance device is characterized by the combination of a spring and a lever to achieve balance.

According to this known technique, the fulcrum and the point of force are always located at the same location regardless of the position of the load (for example, the weight shown in FIG. 1), resulting in a balanced device.

One type of diagnostic X-ray apparatus that has been improved on this mechanical principle and is used in the medical field is a mobile X-ray apparatus that can be easily moved to a hospital room or the like.

Figure 1 shows its structure, in which a support 5 for supporting a main body 3 incorporating an X-ray control device, a power supply, an operation console, etc., and an X-ray tube 4 is attached to a cart 2 with wheels 1. .

A lifter 6 is attached to the column 5 and can be moved up and down on the column 5 and can be moved horizontally by a connecting mechanism.

The tip of this lifter 6 and the X-ray tube 4 are connected by two parallel bars 7, 7', and these two bars 7.
Both ends of 7' are pivotally connected to the X-ray tube 4 and lifter 6 so as to be rotatable in the vertical direction.

Near the rear of the pivot point of the bar 7 pivoted on the upper side of the lifter 6 side and the bar 7 pivoted on the lower side of the X-ray tube 4.
A balancing spring 8 is stretched between the pivot point 1 and the pivot point 1 to maintain balance in the vertical movement of the X-ray tube 4.

Reference numeral 9 denotes a drive wheel for driving and moving the trolley 2.

In such a device, the height of the X-ray tube 4 is roughly adjusted by vertically moving a lifter 6 attached to a support column 5, and the height of the X-ray tube 4 is adjusted by a pantograph mechanism formed by a spring 8 and bars 7, 7'. Make fine adjustments to the height.

That is, adjusting the height of the X-ray tube 4 by moving only the lifter 6 does not provide a sufficient stroke and makes fine adjustment difficult, so a pantograph mechanism with a balancing function is used to compensate for these problems. .

Figure 2 shows the details of this pantograph mechanism.

In the figure, 6 is the above-mentioned lid, 4a is the mounting part on the X-ray tube 4 side, and 7
．． 7' is the aforementioned bar, and 8 is a spring.

A is the pivoting part of the bar 7 on the lid 3 side, B is the pivoting part of the bar 7' on the lid 3 side, C is the mounting shaft of the spring 8 on the lifter 6 side, D
is the pivot joint of the bar 7 on the X-ray tube mounting part 4a side, and E is the pivot part of the bar 7
This is the pivot portion on the side of the X-ray tube attachment portion 4a.

The spring 8 includes a cylindrical main body 8a, a shaft 8b that is movably housed within the main body 8a, and has one end protruding outward from the main body 8a, and a shaft 8b that is attached within the main body 8a.
a guide tube 8C that guides the guide tube 8C; a coil-shaped first spring 8d provided outside the guide tube 8C and slightly longer than the guide tube 8C; a first spring 8d provided outside the first spring 8d; longer second spring 8
e, a presser foot 8f attached near the inner end of the main body 8a of the shaft 8b to press down the second spring 8e; a presser foot 8f attached slightly closer to the guide tube 8C than the presser foot 8f; a nut 8 that comes into contact with and compresses the first spring 8d when moved appropriately;
g, and the one end of the shirt}8b is connected to the shirt T7.
It is pivotally connected to the pivot point E of '.

(2) is the intersection of the axis H of the shaft (8b) of the spring 8 and the tangent to the mounting axis C, which is perpendicular to the axis H of the spring 8; the axial center of the mounting shaft C is on the horizontal line J passing through the point A; The line connecting point B is determined so as to intersect the line H at right angles.

The pantograph mechanism as described above is constructed such that the bars 7 and 7' are rotatable around pivot points A and B, respectively, and
When the wire tube 4 is lowered, the line segment CE7f increases geometrically, that is, the shaft 8b is pulled toward the E side, first the second spring 8e is compressed, and when the shaft 8b is further pulled, the second spring 8e is attached to the shaft 8b. The nut 8g contacts the first spring 8d and compresses it, and when it is further pulled, the nut 8g finally contacts the tip of the guide tube 8C, preventing further downward rotation of the bar 7.7'. be done.

Now, the weight of the X-ray tube 4 is W, AD-BE=. L,,<EB
G=ZDAJ-θ, (62°≧θ≧-41.5°), where G is a horizontal line passing through B, J is a horizontal line passing through C, and θ is the upper side of horizontal lines G and J in the drawing, respectively. Correct.

Here, the force of the spring is F, and the force of the spring when θ=62° is F.

, draw a perpendicular line from point B to the grape, the length to the intersection ■ is l, CE-1 (θ), CE at θ-62° is l (θ)
o, ECJ-β, AB= a, AC= b, then
The equilibrium condition equation for spring balance is as follows.

In equation (3), since W, L, a, and b are constant, the theoretical value F1 of F can be obtained by substituting the value of θ.

l(θ) increases as θ decreases as described above, but l(θ)−l(θ).

Let δ (i.e., the deflection of the spring) be l(θ)
Since =(Lcosθ+b)/cosβ, it follows.

That is, δ is also found by substituting the value of θ.

Therefore, from equations (3) and (4), 62°≧θ>−41
．． By determining F and δ at 5°, the relationship between F1 and δ is expressed as the solid line in FIG. 3, and it can be seen that balance cannot be achieved with a single spring whose load changes linearly with respect to δ.

For this purpose, conventionally, the balance is provided by a spring 8e with a spring constant of K1 until δ=M, and after that, the spring constant is K2.
In combination with spring 8d, the spring constant is K1+K2
It was approximately balanced by increasing the amount.

In other words, a two-stage spring method was used, but in this case, the mechanism becomes complicated because two springs are used, and when δ is larger than M, the amount of unbalance becomes large, which further increases the cost. overlap with X at the desired position
There are drawbacks such as the wire tube 4 not being able to stand still.

The present invention was developed in view of the above-mentioned circumstances, and uses a lever whose middle part is pivoted at the above-mentioned point (2). Provides a pantograph-type spring balance mechanism that eliminates the above-mentioned drawbacks by making it possible to change the spring force in two stages with a single spring, with a stopper that restricts rotation and further rotation. The goal is to do that.

An embodiment of the present invention will be described below with reference to FIGS. 4 to 6.

FIG. 4 is a side view showing the configuration of this device, in which 6 is the aforementioned lid, 4a is the aforementioned X-ray tube attachment part, and 7 and 7' are two bars arranged in parallel in the vertical direction. One end of the bar 7 is pivotally connected to point A of the lid 3, and the other end of the bar 7 is pivotally connected to the point A of the bar 7 and the lid 6, and the other end of the bar 7 is connected to the mounting portion 4a (7) D.
The other end of the bar 7' is pivotally connected to the point E of the mounting portion 4a, and the X-ray tube 4 is held rotatably around the lifter 6.

As mentioned above, points A and B are located on the same vertical line, and points D and E are also located on the same vertical line, and when the bar 7 is in a horizontal state on the horizontal line passing through point A, A lever 41 having a rotation axis at the rear position C' of this bar 7
will be established.

This lever 41 has a rotating shaft 41 with its intermediate portion located at point C'.
The lifter 6 is pivoted at a point a and is provided with a stopper 42 that comes into contact with one end of the lever 41 to prevent further rotation when the lever 41 is appropriately rotated in the counterclockwise direction shown in the figure. .

A spring 43 with a tension adjuster 43a is stretched between the other end of the lever 41 and the point E.

According to the above structure, when the X-ray tube 4 is lowered, for example, the spring 43 pulls the lever 41 until one end of the lever 41 hits the stopper 42.
Rotate 1 to the left.

When this lever 41 hits the stopper 42 due to rotation,
Since the rotation of the lever 41 is prevented from now on, the spring 4
3 is stretched using the connection point with the lever 41 (this is designated as φ) as a fulcrum.

This situation is shown in FIG.

In FIG. 5, a perpendicular line is drawn from point B to the line segment Eφ, which is the central axis of the spring 43, and the intersection point is P, and the line segment E
Draw a perpendicular line to C, let the intersection be Q, BP-l1, BQ
-l2, between l1 and l2, l 1 > l 2
A relationship will be established.

That is, as you can see, conventionally C was always the center of rotation of the spring, so when the X-ray tube 4 is lowered,
The value of l decreases extremely and the balance conditional expression becomes WLc.
Since osθ−Fl, if F increases temporarily, balance cannot be achieved in the range of δ>M.

Therefore, in the present invention, by changing the center of rotation of the spring 43 midway and appropriately selecting the position of the fulcrum φ, it is possible to approximately balance the balance conditional expression if F increases linearly. As shown in FIG. 6, the theoretical value and the actual value can be brought closer to each other with just one spring.

In this way, in a pantograph-type spring balance mechanism, one end of the balance spring is supported by one end of a lever that has a rotating wheel in the center and is prevented from rotating when rotated by a predetermined angle, so that the fulcrum position of the spring can be adjusted. By changing the spring force along the way, the spring force should be adjusted to suit when the X-ray tube lid, which requires the most tension, is near the horizontal position, and when it is above or below the X-ray tube lid, which requires less tension. Therefore, it is possible to provide a spring balance mechanism that has the excellent feature of being able to always obtain the necessary spring force with a single spring and maintaining extremely good balance.

The present invention is not limited to the embodiments described above and shown in the drawings, and can be implemented with appropriate modifications within the scope of the gist; for example, the spring may be a spring tube instead of a tension spring. A compression spring may be used, and the fulcrum of the spring may be changed two or more times if necessary.

[Brief explanation of the drawing]

Figure 1 is a side view for explaining the mobile X-ray diagnostic device;
Fig. 2 is a diagram showing a conventional pantograph mechanism, Fig. 3 is a diagram showing the relationship between the spring force and the amount of deflection of the spring, Fig. 4 is a diagram showing an embodiment of the present invention, and Fig. 5 6 is a diagram for explaining the intermediate operation, and FIG. 6 is a diagram showing the relationship between the spring force of the device of the present invention and the amount of extension of the spring. 3... Lifter, 4a... X-ray tube mounting part, 7, 7'... Bar, 41... Lever, 42...・Stoppa, 43...Spring.

Claims (1)

[Scope of utility model registration request] At least one pair of arms each having a parallelogram shape and each supported by a rotating shaft at both ends is connected between the heavy object and the fixed object, and one end is connected to the heavy object and the other end is connected to the fixed object. In the spring balance mechanism, the fixed object includes a lever rotatable in the moving direction of the arm and pivotally supported at a position apart from one end side. a stopper that connects the other end of the spring member to the one end side end of the lever member and prevents rotation of the lever member at an angular position near the horizontal position of the arm downwardly; A spring balance mechanism characterized in that one member is fixed to the fixed object.