JPH01170414A - Hydraulic actuating mechanism for chair and the like - Google Patents

Abstract

PURPOSE:To maintain a normal operation even when an abnormal load is applied on a mechanism by connecting a flow rate regulating valve which maintains constant flow rate on the flowout side of a fluid flow path at a leg pad of a chair where an operating fluid does not move to either direction. CONSTITUTION:A flow rate regulating valve 25 is connected to a point between an output side solenoid valve 23b of the returning fluid flow path 18b of a hydraulic mechanism 12, and a hydraulic discharge path 19. When an actuating mechanism 6 inclines backward, and during its returning motion to a position where the fluid does not move, and if a person stands up on a step 8, for example, applying an abnormal load thereon, the pressure flowing from the inlet port 38 of the regulating valve 25 is heightened, causing the pressure rise in a chamber having a projection 36 thereby, a piston 39 slides against the resiliency of a spring 40. By this action, the hydraulic flow rate from an inlet port 44 reduces, thereby maintaining the differential pressure values at the fore-end part and at the aft-end part of an orifice 42 at normal state.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present application relates to a hydraulically actuated mechanism for a chair or the like in which an actuating member such as a leg cradle in a treatment or hairdressing chair is actuated by a hydraulically actuated body.

Conventional technology Traditionally, on the back of a seat that is attached to the top of a pedestal that can be raised and lowered,
For example, dental treatment, in which a backrest and a lower limb holder having a step at the lower end are attached to the front part of the seat so that they can be raised and lowered, and the backrest and the lower limb holder are moved up and down by a hydraulic actuating body. chairs are known.

Problems to be Solved by the Invention However, in the case of the above-mentioned chair, in the past, the back and leg rests were laid down, so when the treatment work was completed, the back and leg rests were moved to stand up. When a worker stands up on step 7 while they are not fully standing up, the worker's weight is applied as a large load to the hydraulic actuator that operates the lower limb rests. It acts rapidly, thereby creating more or less a vacuum in the oil flow system.

As a result, there is play in the subsequent hydraulic operation, resulting in a lack of smooth operation.Also, when the backrest and leg rest are laid down from an upright position, until the vacuum created in the oil distribution system is filled with oil, Since the lodging operation was not performed, there was a defect in that the stability of the operation was impaired.

Means for Solving the Problems Therefore, the present application improves the above-mentioned defects of the conventional system, and uses the movement of the piston rod in the hydraulic actuator to move the actuating member such as the lower limb cradle between the inactive position and the actuated position. In a hydraulically operated mechanism such as a chair that is moved between positions, a predetermined amount of oil is always allowed to flow to the outflow side of the oil flow passage in the non-operating direction of the leg cradle, and the leg cradle is not activated. Connecting an adjustable flow rate regulating valve that limits the flow rate of the oil in response to an increase in oil pressure when an abnormal load is applied to the operating member in the operating direction and maintains the amount of oil flowing out at a constant level. It is characterized by:

Function: When pressurized oil is supplied from one end of the cylinder in the hydraulic actuator and the oil flows out from the other end, the piston rod is actuated to tilt, for example, the lower leg support of a chair in the direction of collapse. From this state, pressurized oil is supplied from the other end of the cylinder in the hydraulic actuator, and when the oil flows out from one end, the piston rod operates in the opposite direction, for example, The lower limb cradle tilts in the standing direction and reaches the inoperative position, and during the above operation, the flow! The regulating valve allows the flow of a predetermined amount of oil.

In the above, the piston rod operates in the opposite direction, and for example, while the leg cradle is operating in the standing direction, the worker stands up on the step provided on the leg cradle, and the worker's entire weight acts on the step. At this time, an abnormal load is applied to the piston rod, causing the oil pressure on the outflow side to increase, and as the oil pressure increases, the flow rate regulating valve limits the amount of oil flowing. In other words, even if the pressure on the inflow side of the flow rate regulating valve increases, the flow rate on the outflow side is held constant, so that the piston rod restores the leg cradle to normal operation.

Then, when the load applied to the step is removed, the flow Wt regulating valve restores to the predetermined fiffi and maintains the normal operation of the piston rod.

Embodiment The embodiment of the present application will be described in detail based on the drawings below.
(1) stands on a base (2) and is raised and lowered by hydraulic pressure, and on top of that is a seat (3).
) is installed horizontally. (4) is a backrest attached to the back of the seat (3) so as to be able to rise and fall freely around the pivot point (5), and (6) is a pair of parallel ring pieces attached to the front lower part of the seat (3). The upper ends of (7)a and (7)b are pivotally connected, and the lower ends are connected to the connecting pieces (9) provided at the rear of each step (8).
) is an operating mechanism that is pivoted at the front and back positions of the
A lower limb cradle (10) is provided. (11) is an interlocking rod that connects the lower end of the support (4) and the operating mechanism (6), and (12) is a cylinder (12) horizontally arranged at the bottom opening of the seat (3). ) a and piston rod (12)
The rear end of the cylinder (12)a is attached to the back of the seat (3) via a support piece (13), and the tip of the piston rod (12)b is connected to the operating mechanism. (6) is attached.

FIG. 2 shows a hydraulic control system diagram of the hydraulic actuating body (12), in which (15) is an oil tank, and (16) is a forced flow of oil from the oil tank (15) through a filter (17). The hydraulic pump (18)a and (18)b are the forward flow passage and return flow passage of the hydraulic actuating body (12) connected in parallel between the oil pump (16) and the oil drain passage (19). A check valve (2) is provided in the forward flow passage (18)a.
0) a, input side solenoid valve (21) a, filter <22)
a and the output side solenoid valve (23) a are connected in series, and the double-acting flow passage (18) b includes a check valve (20) b, an input end solenoid valve (21) b, a filter (22) a, The output side solenoid valve (23)a and the regulating valve (24) are each connected in series,
In addition, the rear end and front end of the cylinder (12)a of the hydraulic actuator (12) are connected to the filters (22)a and (22)b, respectively, and the present application provides hydraulic control with the above-described configuration. In the system, when abnormal pressure acts on the piston rod (12) b between the output side solenoid valve (23) b of the double-acting flow passage (18) b and the oil drain passage (19), the oil 2it restricts the distribution of! A regulating valve (25) is connected.

Specifically, as shown in FIG. 3, a relatively large diameter adjustment hole (31) is formed in the upper part of the valve body (30) and penetrates in the axial direction.
A flow path (32) is provided at the bottom of each hole, and a sealing piece (33) is provided at both ends of the adjustment hole (31).
), (34) are screwed together, and there is a circumferential groove (35) long in the axial direction on the outer periphery of the intermediate part between them, and a protrusion (36) at the center of one end surface. Along with having,
The protrusion (36) extends in the axial direction from the circumferential groove (35).
A piston (39) is provided with a small diameter through hole (38) which opens at one end surface having a
However, there is a spring (40) interposed therebetween which presses in the direction of contacting one of the sealing pieces (34). The flow path (32
) is a throttle valve (41) screwed into the intermediate part for external operation.
It has a small-diameter orifice (42) for adjusting the flow rate, one end of which is connected to the outlet (43) that opens at the outer periphery of the valve body (30), and the other end of which is connected to the piston (39).
The valve body (30) has an opening that is connected to the circumferential groove (35) when the piston (39) moves in the axial direction. A variable inflow port (44) and a small-diameter ventilation hole (46) communicating with the flow path (32) and opening in a chamber (45) in which the spring (40) is interposed are provided.

The hydraulic pump (16) is driven from the inoperative position shown by the solid line in FIG. When the input side of the solenoid valve (21) a and the output side solenoid valve (23) a are operated respectively, the oil flows into the hydraulic actuating body (
Oil flows into the rear end of the cylinder (12)a of the hydraulic actuator (12) and flows out from the front end of the cylinder (12), causing the piston rod (12)b of the hydraulic actuator (12) to move in the projecting direction. In FIG. 1, the actuating mechanism (6) is tilted forward and the backrest (4) is tilted backward via the interlocking rod (11) to reach the actuating position shown in phantom lines in FIG.

In addition, in Fig. 2, when the output side solenoid valve (23) b of the forward flow path (1B) a and the input side solenoid valve (21) b of the backward flow path (18) b are operated, the hydraulic pump (16) The oil flows into the front end of the cylinder (12) a and flows out from the rear end, causing the piston rod (12) b of the hydraulic actuating body (12) to move in the retracting direction. In Figure 1, the operating mechanism (6) tilts rearward, and the lower limb cradle (lO) and backrest (4) return from the operating position indicated by the phantom line in the figure to the non-operating position indicated by the solid line in the figure.

During this restoring operation, for example, if the worker stands up on the step (8) and an abnormal load is applied to the step (8), the piston rod (12) of the hydraulic actuator (12) A force in the retraction direction acts on b, and this force acting in the retraction direction increases the oil pressure on the outflow side of the return flow passage (18)b.

For example, in FIG. 3, when the flow rate adjustment valve (25) is not provided, the oil in the chamber p suddenly flows out into the oil tank (15) through the oil drain path (19) due to the increase in pressure. As a result, a vacuum portion is created within the oil flow path, but the presence of the flow rate regulating valve (25) provides the following effects.

That is, oil flowing in from the inlet (44) flows into the chamber and flow passage (32) of the protrusion (36) through the through hole (38), and also flows into the outlet (4) through the orifice (42).
3) The axial balance of the piston (39) in the normal state is maintained by supplementing the pressure difference between the front and rear ends of the orifice (42) with the elastic force of the spring. And in this normal state, the inlet (
When the pressure flowing from the protrusion (38) increases, the pressure in the chamber of the protrusion (36) also increases, causing the above-mentioned balanced state to collapse and the piston (39) to move towards the spring (40).
This causes the opening of the inlet (44) to be small (restricted) and the amount of oil inflow is reduced, so that
The pressure difference between the front and rear ends of the orifice (42) is maintained in a normal state, and the piston (39) is connected to the inlet (44).
), therefore, the hydraulic actuating body (12) maintains normal operation and the backward movement of the lower limb cradle (8) is also maintained.

In addition, in FIG. 3, the flow rate can be adjusted by adjusting the shutoff valve (41).

Effects of the Invention Since the present application is constructed as described above, even if an abnormal load is applied to the piston rod of the actuating body, normal operation can be maintained without the risk of creating a vacuum in the oil distribution system. ,
Therefore, it has the advantage that smooth and stable operation can be obtained.

[Brief explanation of the drawing]

The drawings show an embodiment of the present application, and FIG. 1 is a general side view of the chair, FIG. 2 is a hydraulic control system diagram, and FIG. 3 is a sectional view of a flow rate regulating valve. In the diagram, A is a chair, (1) is a pillar, (3) is a pedestal, (4)
is the backrest, (6) is the operating mechanism, (8) is the step, (1
0) is the leg pedestal, (16) is the pump, (21)a,
(21)b is a magnetic valve on the inflow side, (23)a, (23)
b is an outflow side solenoid valve, and (25) is a flow rate adjustment valve. Patent applicant: Yoshida Seisakusho Co., Ltd.

Claims (1)

[Claims] Due to the movement of the piston rod in the hydraulic actuating body,
In a hydraulically operated mechanism such as a chair that moves an operating member such as a leg cradle between an inoperative position and an operative position, there is always a predetermined position on the outflow side of the oil flow passage in the inoperative direction of the leg cradle. Allowing the flow of oil, and restricting the flow of oil in response to an increase in oil pressure when an abnormal load is applied to the operating member in the non-operating direction of the lower limb cradle, thereby reducing the amount of oil flowing out. Hydraulic operating mechanism for chairs, etc., characterized by connecting an adjustable flow regulating valve to maintain a constant flow rate.