JPS6140856B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a vibration prevention device for a dehydrator that suppresses abnormal vibrations of a rotating tank for dehydration due to unbalanced distribution of materials to be dehydrated.

First, to explain a conventional device of this type, FIG. 1 shows a washing machine with a dehydrating function as an example of a dehydrating machine. In this Figure 1, 1
is an outer box, inside which a tab 2 is elastically suspended by a hanging rod 3, and inside this tub 2, a rotary tank 4 for dehydration is rotatably provided. A stirring blade 5 is provided at the inner bottom. Reference numeral 6 denotes a motor for selectively transmitting rotational force to the rotary tank 4 and the stirring blades 5 via the power transmission mechanism 7, and 8 is a so-called balancer provided at the upper end opening of the rotary tank 4. This balancer 8 is for suppressing abnormal vibrations in which the entire tub 2 including the rotating tank 4 swings around abnormally due to unbalanced distribution of the dehydrated material inside the rotating tank 4 during high-speed rotation during dewatering. It is. This conventional balancer 8 can be roughly divided into three types.The first type is a concrete balancer in which an annular case is filled with concrete, and the second type is a concrete balancer in which a liquid is fluidly sealed in an annular case. The third type of balancer is a ball balancer in which a plurality of steel balls are movably housed in an annular case. It is already known that these various balancers exhibit vibration suppression characteristics as shown in FIG. In FIG. 2, A is the vibration amplitude of the upper end of the tab 2 during steady rotation of the rotating tank 4, and Q is the mass of the material to be removed that is unbalanced in the rotating tank 4 (hereinafter referred to as the unbalance amount). , 9 is a characteristic line of the concrete balancer, 10 is a characteristic line of the liquid balancer, and 11 is a characteristic line of the ball balancer. Incidentally, since the characteristics shown in FIG. 2 were created through experiments by the present inventor, specific numerical values are shown for A and Q. As is clear from the comparison of the characteristic lines 9, 10, and 11 above, the ball balancer is particularly effective in suppressing vibrations. However, the excellent characteristics shown by the characteristic line 11 of the ball balancer are exhibited when the rotating tank 4 is made of metal that does not bend, and according to the experiments of the present inventor, the rotating tank 4 It was found that when the ball balancer was applied to the ball balancer made of plastic with excellent productivity, the vibration suppression characteristics were as shown by the characteristic line 12, and the performance was inferior to that of the liquid balancer. It was also found that the cause was the deflection of the plastic rotating tank 4. This will be explained in detail below. FIG. 3 schematically shows the rotary tank 4 and the ball balancer 13 provided therein as a plan view, and FIGS. 4 and 5 show the dewatering shaft 1.
4, a plastic rotating tank 4 is shown diagrammatically in a side view. 15 is an unbalanced load (material to be dehydrated). When the rotating tank 4 is rotating steadily with an unbalanced distribution of the material to be dehydrated as shown in FIGS. 3 and 4, the dehydration shaft 14
center (S1-S2 line) and center of rotation (P1-P2
Since centrifugal force is generated centering on (P1-P2 line) due to the relationship with (line), the steel ball 16 at this time is opposite to the unbalanced load 15 position due to the circumferential component force fbo of the centrifugal force fb. Move to the side. In the vibration generation force, that is, the excitation force, in this state, the force F in the translational direction and the rotational moment M are expressed by the following formulas (a) and (b).
It is represented by.

F=Fu−Fb…(a) M=Fu・Lu−Fb・Lb…(b) As understood from this equation, F and M are reduced by Fb and Fb・Lb by the ball balancer 13, The amplitude of vibration is suppressed. In addition, Fu
is the centrifugal force acting on the unbalanced load 15, Fb
is the centrifugal force acting on the entire steel ball, and Lu and Lb are the distances between the center of gravity G, the center of the unbalanced load, and the center of the group of 16 steel balls (see Fig. 4). In the above, when all the steel balls 16 are located on the opposite side of the unbalanced load 15 as shown in FIG. 3, the unbalance absorption limit point is reached as shown by R1 in FIG. As the oscillation amplitude increases, the vibration amplitude also increases rapidly. Now, if the rotating tank 4 is made of plastic, it will bend as shown in FIG. That is, the steel balls gather together until the rotation center (P1-P2 line) and the rotation center S3 of the ball balancer 13 in the dehydration direction coincide, and at this time, the force
Due to Fb, the rotating tank 4 is deflected by △a in Fig. 4. As a result, the rotation center (P1-P2 line) and the dehydration shaft center (S1-S2 line) are offset by the amount of deflection △a, and this shift is essentially zero in an ideal balancer. This causes the effect to deteriorate, and the vibration suppressing effect is lower than that of a metal material that does not cause deflection, as shown by the characteristic line 12 in FIG. Therefore, as the amount of unbalance increases, the amount of steel balls 16 that gather on the side opposite to the unbalanced load 15 also increases, further promoting deflection and reducing the vibration suppressing effect. Even when such deflection occurs, there is an unbalance absorption limit point as shown by R2 in Fig. 2, but in the case of the plastic rotating tank 4, the amount of unbalance increases to exceed the unbalance limit point R2. However, since all the steel balls 16 are already completely gathered together at the limit point R2, there is no increase in the force Fb, and therefore the deflection Δa remains constant. Since the vibration amplitude caused by the amount of unbalance exceeding the limit point R2 has a phase different from the deflection amount Δa by 180 degrees, S2 shown in FIG. 4 approaches P2 as the amount of unbalance increases. Eventually, the vibration amplitude becomes zero (R3 in Figure 4).
point), and thereafter the positional relationship between S2 and P2 is reversed as shown in Figure 5, and the vibration suppressing effect increases again as shown from point R3 on characteristic line 12 in Figure 2. I'll come.

As can be understood from the above explanation, although ball balancers have the best vibration suppression performance, if the rotating tank is made of plastic,
Due to the deflection, the vibration amplitude decreases from the unbalance absorption limit point R2 to the amplitude zero, but because the decrease is rapid, it increases again with a small increase in the amount of unbalance, making it difficult to use as a ball balancer. Excellent performance will be lost. On the other hand, if the number of steel balls is increased and the unbalance absorption limit point is shifted to the side where the amount of unbalance is large, a new drawback arises in that the maximum vibration amplitude increases.

The present invention was made in view of the above circumstances, and its purpose is to effectively reduce vibrations during steady rotation even when the rotating tank is made of plastic by having a so-called ball balancer section and a liquid balancer section. To provide a vibration prevention device for a dehydrator that can suppress vibration amplitude and narrow the range of change in vibration amplitude over a wide range of changes in unbalance.

An embodiment of the present invention will be described below with reference to FIGS. 6 to 8. Reference numeral 20 designates a washing and dewatering rotating tank rotatably disposed within a tub 21 similar to that shown in FIG. 1, and is integrally molded from plastic. This rotating tank 2
A balancer 22 is attached to the inner periphery of the open upper end of the rotary tank 20 so as to be concentric with the rotary tank 20. This balancer 2
2, 23 is a plastic annular case, and the upper and lower parts of the case 23 are integrally molded to have a first annular chamber 25 and a second annular chamber separated by a partition wall 24. annular chamber 2
6 respectively. Reference numeral 27 denotes a so-called baffle plate, and a plurality of baffle plates are formed intermittently in the circumferential direction so as to protrude inward from the outer inner peripheral surface of the first annular chamber 27, as in the case of a well-known liquid balancer. are doing. 2
Reference numeral 8 denotes a first sealing plate having an annular shape, and is provided to liquid-tightly close the upper end opening of the first annular chamber 27 with an appropriate amount of liquid (for example, salt water) 29 contained therein that can freely flow therein. ing. Reference numeral 30 denotes a second sealing plate, which is provided to close the lower end opening of the second annular chamber 26 with an appropriate number of spheres, for example, steel balls 31 movably accommodated therein. In addition, 32 is case 2
3 to the rotary tank 20, and is integrally formed on the outer periphery of the case 23. Since Fig. 7 is for explaining the action in the same way as Fig. 4, this Fig. 7 also includes Fig. 4.
The same parts as those in the figure and FIG. 6 are given the same reference numerals.
FIG. 8 shows the vibration suppression characteristics of the balancer 22 of the present invention, which was created in the same manner as in FIG. In this Figure 8, T1-T2-T3-T
The 4th line is the characteristic line by the balancer 22, T1-T2-
The T5-T6 line is a characteristic line based only on the ball balancer, and the dotted line 33 is a characteristic line based only on the liquid balancer. Now, considering the rotating tank 20 during steady rotation,
In the excitation force that generates the vibration at this time, the force F in the translational direction and the rotational moment M are expressed by the following equations (c) and (d) when they are below the unbalance absorption limit point shown by T2 in Fig. 8. When it is above the unbalance absorption limit point, it is expressed by the following equations (E) and (F).

F=Fu−Fb…(c) M=Fu・Lu−Fb・Lb…(d) F=Fu−Fb−Fw…(e) M=Fn・Lu−Fb・Lb−Fw・Lw…(f) In this equation, Fw is the centrifugal force acting on the liquid 29, and Lw is the distance between the center of gravity G and the center of the most concentrated portion of the liquid 29. As can be understood from the above equation, below the unbalance absorption limit point, the vibration suppressing action shown by the characteristic line T1-T2 is mainly exerted by the steel balls 31, and above the unbalance absorption limit point, the vibration suppressing effect shown by the characteristic line T1-T2 is mainly exerted by the steel ball The so-called liquid balancer effect due to 29 is exhibited and the characteristic line T2-T3
A vibration suppressing effect having the characteristics shown between -T4 is produced. In this case as well, the balancer 22 is partially composed of the steel balls 31 and serves as a ball balancer, so as shown at T3, due to the deflection of the rotating tank 20, the vibration amplitude is approximately zero, similar to that described in FIG. A state exists. As shown between the characteristic line T2 and T3, according to this balancer 22, the degree of decrease in the vibration amplitude A as the unbalance amount Q increases due to the liquid balancer effect is reduced between R2 and R3 in FIG. Compared to the conventional model shown in , this is extremely gentle, and this is due to the effective use of the stiffness of the plastic rotating tank 20, and when viewed as a whole, the unbalance amount Q changes over a wide range. This means that the range of vibration amplitude A at the upper end of the tab 21 can be made narrower. As described above, according to this balancer 22, vibration is suppressed by the ball balancer effect of the steel balls 31 below the unbalance absorption limit point due to deflection of the rotating tank 20 due to the steel balls 31, and above the above absorption limit point. In this case, the degree of reduction in vibration amplitude caused by the ball balancer effect due to the increase in deflection of the rotating tank 20 is moderated by the liquid balancer effect, and as a result, even if the amount of unbalance changes over a wide range, The amplitude of vibration can always be suppressed to a narrow level. In addition, in the explanation of Fig. 2, the case where the unbalance absorption limit point is reached at an unbalance amount (approximately 0.7 kg) is used as an example, but as shown in Fig. 8, which is an embodiment of the present invention, from the above, By setting the unbalance absorption limit point so that the unbalance absorption limit point is reached at a small amount of unbalance (approximately 0.45 kg), the maximum value of the vibration amplitude due to the deflection of the plastic rotating tank 20 can be determined by setting the unbalance absorption limit point. It is also possible to set it to be even smaller. In particular, according to the embodiment of the present invention, the first annular chamber 25 is formed independent of the second annular chamber 26 accommodating the steel ball 31, and the liquid 2
Since the steel ball 31 is accommodated in the steel ball 31, the steel ball 31
In addition to reliably preventing the movement of the liquid 29 and the steel balls 31 from being obstructed by the baffle plate 27,
Steel balls 31 are of concern when they are housed in the same room.
Rust caused by the liquid 29 can be prevented. Also,
The first and second annular chambers 25 and 26 are placed in the same case 2.
3, it is possible to eliminate the deviation of the geometrical center between the liquid balancer part made of the liquid 29 and the ball balancer part made of the steel balls 31, so that the vibration suppressing effect can be efficiently exhibited. Moreover, it is possible to simultaneously solve the problem of noise caused by misalignment and vibration between the two parts, which occurs when the two parts are made independent of each other. Furthermore, the upper annular chamber 2 is divided by a partition wall 24 formed integrally within the case 23.
Since the liquid is stored in the chamber 5, there is no fear of liquid leakage that would occur if the liquid 29 is stored in the lower annular chamber 26 whose lower end opening is closed by a separate sealing plate 30. This simplifies measures against liquid leakage and improves productivity.

As described above, the present invention provides a plastic rotary tank with first and second annular chambers concentrically therewith, and in which a liquid is contained in the first annular chamber in a freely flowing manner and a liquid is contained in the second annular chamber. It is characterized by housing a plurality of spheres in a movable manner, and as a result, vibrations caused by the deflection of the spheres during steady rotation of the rotating tank are generated together with vibrations due to unbalanced distribution of the material to be dehydrated. Also, it is possible to provide a vibration prevention device for a dehydrator that can suppress the vibration amplitude so that it always becomes narrow against a wide range of changes in the amount of unbalance.

[Brief explanation of the drawing]

Figures 1 to 5 are for explaining conventional examples, in which Figure 1 is a theoretical vertical cross-sectional side view of a washing machine with dehydrating function, Figure 2 is a characteristic diagram regarding vibration suppression by a ball balancer, etc. FIG. 3 is a plan view schematically showing the rotary tank for explaining the operation, FIGS. 4 and 5 are side views schematically showing the rotary tank in different states, and FIGS. 6 to 8 are This relates to one embodiment of the present invention, in which Fig. 6 is a vertical sectional side view of the balancer mounting part of the rotating tank, Fig. 7 is a schematic side view for explaining the action, and Fig. 8 is a characteristic diagram of vibration suppression. It is. In the figure, 20 is a rotating tank, 23 is a case, 25 is a first annular chamber, 26 is a second annular chamber, 29 is a liquid,
31 is a steel ball (spherical body).

Claims (1)

[Scope of Claims] 1. A plastic rotating tank is provided with first and second annular chambers concentrically therewith, and the first annular chamber accommodates liquid in a freely flowing manner, and the second annular chamber contains a plurality of annular chambers. A vibration prevention device for a dehydrator, characterized by movably housing a sphere. 2. The vibration prevention device for a dehydrator according to claim 1, wherein the first and second annular chambers are integrally formed in the same case. 3. The vibration prevention device for a dehydrator according to claim 2, wherein the first annular chamber is located above the second annular chamber.