JPH10146360A - Vibration proof bed for use in ambulance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the damper function of an actuator from being impaired even if a bed is varied in height or tilted and to fix the bed at a certain height as necessary. SOLUTION: A bed is supported against a base by means of a pair of front and rear hydraulic actuators 10 in such a way that it can be raised and lowered. Each actuator 10 comprises a pair of upper and lower oil chambers 17, 18 defined by fitting a piston 12 into a cylinder 9. The cylinder 9 is connected to the base 22, a rod 13 projecting upward from the piston 12 is connected to the bed, and a throttle passage through which the pair of upper and lower oil chambers 17, 18 communicate with each other is formed. The lower roil chamber 18 of the actuator 10 can be connected to either the discharge opening of a hydraulic pump 4 or an oil tank 2 by a direction changing valve 6, and a pressure accumulator 7 is connected to the lower oil camber 18. A switching valve is disposed in the throttle passage.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an anti-vibration bed for an ambulance vehicle mounted on an ambulance vehicle, and particularly to effectively prevent vibration of a vehicle body from being transmitted to a gantry or a berth. The present invention relates to an anti-vibration bed for an ambulance vehicle, which can be fixed at an arbitrary height.

[0002]

2. Description of the Related Art As disclosed in Japanese Patent Application Laid-Open Nos. 1-192353 and 4-210057, an anti-vibration bed mounted on an ambulance vehicle is designed to cut off vibration of a vehicle body with respect to the bed. A pair of front and rear hydraulic actuators and springs are disposed between the floor of the vehicle and the bed, and the bed moves up and down by adjusting the amount of oil in the lower oil chamber of the actuator. If the upper and lower oil chambers of the actuator are shut off from a hydraulic source, that is, a hydraulic pump, the actuator functions as a damper mechanism. However, in the above-described anti-vibration bed of an ambulance vehicle, when the bed and the patient's weight act as a damper mechanism only in the floating state of the actuator that balances the drag of the spring, when the bed is changed in height or the bed is tilted back and forth. Cannot exhibit the anti-vibration function. Because when adjusting one or both actuators in the extended or contracted state to adjust the height or tilt of the bed,
This is because the upper and lower oil chambers are hermetically sealed and the bed is fixed, and does not work as a damper mechanism.

Therefore, as disclosed in Japanese Patent Application Laid-Open No. 5-31140, if a pair of front and rear actuators supporting the floor of the vehicle, that is, the lower end of the cylinder can be moved back and forth by another actuator, The actuator that supports the is tilted to adjust the height or tilt of the bed and also acts as a damper mechanism. However, the above-described structure requires two sets of actuators and two sets of directional control valves, which inevitably increases weight and manufacturing costs. In addition, during the switching operation of the directional control valve, the impact is transmitted to the bed, which imposes a physical burden on the patient.

[0004]

SUMMARY OF THE INVENTION In view of the above-mentioned problems, it is an object of the present invention to change the height of a bed or tilt the bed so that the damper function of the actuator is not impaired. It is an object of the present invention to provide an anti-vibration bed for an ambulance vehicle which can be fixed at a height of the vehicle.

[0005]

According to the present invention, a pair of front and rear hydraulic actuators for supporting a bed so as to be able to move up and down with respect to a substrate are provided by inserting a piston into a cylinder. A pair of upper and lower oil chambers are partitioned, the cylinder is connected to the substrate, a rod projecting upward from the piston is connected to the bed, and a throttle passage communicating the upper and lower oil chambers is provided. The lower oil chamber of the actuator is configured to be connectable to one of the discharge port of the hydraulic pump and one of the oil tanks by a direction switching valve, and an accumulator is connected to the lower oil chamber.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The upper and lower oil chambers of a pair of front and rear actuators are communicated by an on-off valve in an external passage or a throttle in an internal passage. The discharge port of the hydraulic pump can communicate with the lower oil chamber of each actuator via the direction switching valve, and a pressure accumulator is connected to the lower oil chamber. Therefore, by adjusting the amount of oil in the lower oil chambers of the pair of front and rear actuators, each actuator is extended or contracted, and the height of the bed is adjusted. If one actuator is extended or contracted, the bed is tilted forward or backward. When the directional control valve is set to the neutral block position in this state, the bed is maintained in a desired posture. At this time, since the upper and lower oil chambers of the actuator are communicated with each other by an on-off valve in an external passage or a throttle in an internal passage, they function as a damper mechanism.

[0007] When the patient is subjected to cardiac pine surge or the like, the bed can be fixed at a desired height by closing the on-off valve.

[0008]

FIG. 1 is a side view showing a schematic configuration of an anti-vibration bed of an emergency vehicle according to the present invention. The anti-vibration bed 21 of the emergency vehicle according to the present invention is supported by a pair of front and rear actuators 10 so as to be able to move up and down and to tilt forward and backward with respect to a substrate 22 fixed to the floor of the emergency vehicle. A pair of left and right links 23 is provided between the front part of the couch 21 and the rear part of the board 22 in a lateral direction in order to limit the back and forth movement of the couch 21 with respect to the board 22 and prevent the couch from tilting to the side. Pins 24, 25
Are linked by Each actuator 10 has a cylinder 9
A pair of upper and lower oil chambers 17 and 18 are defined by inserting a piston 12 into the piston, and a rod 13 connected to the piston 12 projects upward. The lower end of the cylinder 9 is fixed to the substrate 2 by the pins 16.
2 and the upper end of the rod 13 is connected to the bed 21 by the pin 15. The piston 12 is provided therein with a throttle passage 12a communicating the upper oil chamber 17 and the lower oil chamber 18.

As shown in FIG. 2, according to the present invention, the accumulator 7 is connected to the lower oil chamber 18. As is well known, the pressure accumulator 7 is formed by partitioning an air chamber and an oil chamber filled with pressurized air by a diaphragm in a closed container, and the oil chamber is provided in the lower oil chamber 18 of the actuator 10. Communicated. The lower oil chamber 18 of the actuator 10 can be selectively communicated with the discharge port of the hydraulic pump 4 and one of the oil tanks 2 by the direction switching valve 6. Further, the lower oil chamber 18 of the actuator 10 is connected to the hydraulic pump 4 and the oil tank 2 at the neutral position of the directional control valve 6.
Be cut off from. The hydraulic pump 4 sucks the oil in the oil tank 2 through the filter 3 and supplies the oil to the lower oil chamber 18 of the actuator 10 through the directional switching valve 6. When the oil pressure at the discharge port of the hydraulic pump 4 becomes excessive, the oil at the discharge port is returned to the oil tank 2 via the relief valve 5. The direction switching valve 6 may be a manually operated type, but is preferably an electromagnetically driven type.

When the directional control valve 6 is set to the position shown in FIG. 2, the hydraulic oil is supplied from the hydraulic pump 4 to the accumulator 7 via the directional control valve 6, and at the same time, the lower oil chamber 1 of the actuator 10
8. The bed 21 is pushed up by the rod 13 of the piston 12 and raised. At this time, if only one of the pair of directional control valves 6 is set at the position shown in FIG.
Can be tilted forward or backward. Here, the direction switching valve 6
Is returned to the neutral block position, the lower oil chamber 18 of the actuator 10 is shut off from the oil tank 2 and the hydraulic pump 4. Therefore, the load of the bed 21 acting on the piston 12 is
The oil pressure of the lower oil chamber 18 acting on the piston 12 is balanced.

When a sudden force such as pushing up the cylinder 9 acts on the floor of the vehicle body, a part of the oil in the lower oil chamber 18 flows into the upper oil chamber 17 via the throttle passage 12a and simultaneously flows into the accumulator 7. . The upward movement of the cylinder 9 with respect to the piston 12 supporting the bed 21 is allowed, but the sudden and excessive upward movement of the cylinder 9 is suppressed by the fluid resistance of the passage.
Conversely, when a force such that the floor of the vehicle body sinks acts on the cylinder 9, the oil in the upper oil chamber 17 flows through the throttle passage 12 a to the lower oil chamber 18.
At the same time, the oil of the pressure accumulator 7 flows into the lower oil chamber 18 at the same time. Thus, the vibration transmitted from the vehicle body to the bed 21 is reduced. Further, when the bed 21 is raised or lowered or tilted, the lower oil chamber 1 of the actuator 10 accompanying the operation of the direction switching valve 6 is used.
Since the rapid change of the oil amount of 8 is mitigated by the pressure accumulator 7, it is possible to prevent the impact from acting on the bed 21.

When the specifications of the directional control valve 6 and the pressure accumulator 7 are determined as follows for the vibration system of the above-described anti-vibration bed of the emergency vehicle, the following equation is established. Ap • s • Δy + ΔQg = 0 ΔQg = K4 (ΔP1-ΔP2) ΔP2 = -n • P2 '/ z' • Δz ΔQg = -Ag • s • Δz Δw = -Ap • ΔP1, where Ap: Actuator total Effective area Ag: Effective area of accumulator y: Displacement of actuator z: Displacement of air chamber of accumulator Qg: Oil flow into accumulator P1: Internal hydraulic pressure of actuator P2: Internal hydraulic pressure of accumulator K4: Flow rate of throttle Coefficient n: Polytropic coefficient P2 ': Initial air pressure of accumulator air chamber z': Initial displacement of air chamber air chamber w: Disturbance Δ: Expression of minute displacement from equilibrium point s: Laplace operator Can be solved, the operating characteristic of the actuator 10 with respect to the disturbance w can be expressed by the transfer function of the primary system by the following equation. By setting the specifications of the actuator 10, the accumulator 7 and the like to optimal values, Can be effectively prevented from being transmitted to the bed 21. Δy / Δw = −1 / Ap− ² {K4 · z ′ · Ag / (z ′ · Ag · s + n · P2 ′ · K4)} As described above, the present invention relates to the actuator 10 supporting the bed 21. By adjusting the amount of oil in the lower oil chamber 18 by the direction switching valve 6 and connecting the accumulator 7 to the lower oil chamber 18, the height and inclination of the bed 21 can be adjusted to desired values, and the vehicle body can be adjusted. Can be suppressed from being transmitted to the bed 21.

In the embodiment shown in FIG. 3, an opening / closing valve 8 having a throttle passage is inserted and connected to a passage connecting the upper oil chamber 17 and the lower oil chamber 18 provided outside the piston 12, that is, a pipe 19. When adjusting the height or inclination of the bed 21,
First, the on-off valve 8 is closed, and the direction switching valve 6 is switched to adjust the amount of oil in the lower oil chamber 18. When the desired position of the couch 21 is obtained, when the direction switching valve 6 is set to the neutral position and the on-off valve 8 is set to the open position shown in the drawing, the actuator 10 functions as a damper mechanism, and the vibration of the vehicle body is transmitted to the couch 21. Suppress.

When the patient is subjected to cardiac pine surge or the like, when the directional control valve 6 is set to the neutral position and the on-off valve 8 is closed, the bed 21 is fixed at that position or height, and the patient is also fixed to the bed. Therefore, an effective cardiac pine surge can be administered to a patient.

[0015]

As described above, according to the present invention, a pair of front and rear hydraulic actuators which support the bed so as to be able to move up and down with respect to the substrate, insert a piston into a cylinder to partition a pair of upper and lower oil chambers. Connecting the cylinder to the substrate, connecting a rod projecting upward from the piston to the bed, providing a throttle passage communicating the pair of upper and lower oil chambers, and directing the lower oil chamber of the actuator to the lower oil chamber. The switching valve is configured to be connectable to one of the discharge port of the hydraulic pump and one of the oil tanks, and the accumulator is connected to the lower oil chamber. Therefore, even if the height of the bed is changed or the bed is tilted, the actuator can be operated. Damper function is not impaired.

When the on-off valve of the throttle passage is closed, the bed is fixed at the position with respect to the substrate, and the movement of the patient is suppressed, which is convenient for performing cardiac pine surge or the like.

[Brief description of the drawings]

FIG. 1 is a side view showing a schematic configuration of an anti-vibration bed of an emergency vehicle according to the present invention.

FIG. 2 is a hydraulic circuit diagram for controlling an actuator supporting the vibration isolating bed.

FIG. 3 is a hydraulic circuit diagram for controlling an actuator supporting an anti-vibration bed according to a modified embodiment of the present invention.

[Explanation of symbols]

2: Oil tank 3: Filter 4: Hydraulic pump 5: Relief valve 6: Direction switching valve 7: Pressure accumulator 8: Open / close valve 9: Cylinder 10: Actuator 12: Piston 12a: Restrictor passage 13: Rod 15, 16: Pin
17, 18: oil chamber 19: passage 21: bed 22: board 23: link 24, 25: pin

Claims (2)

[Claims] 1. A pair of front and rear hydraulic actuators for supporting a bed so as to be able to move up and down with respect to a substrate, wherein a pair of upper and lower oil chambers are defined by inserting a piston into a cylinder, and the cylinder is mounted on the substrate. , A rod projecting upward from the piston is connected to the bed, a throttle passage communicating the pair of upper and lower oil chambers is provided in the piston, and a lower oil chamber of the actuator is connected to a hydraulic pump by a direction switching valve. And a pressure accumulator is connected to the lower oil chamber, respectively. 2. An anti-vibration bed for an emergency vehicle according to claim 1, wherein an on-off valve is provided in a passage connecting the upper and lower oil chambers of said actuator.