JP2506072B2 - Hydraulic drive control device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a hydraulic drive control device that controls the drive of a driven body by utilizing the pressure of a liquid.

[Technical Background of the Invention and its Problems] Hydraulic technology, particularly hydraulic technology using oil, has been adopted in many fields in recent years because its characteristics meet the requirements for automation of various machines and mechanisms, and reduction in size and weight. Has been done. In the field of medical equipment, this hydraulic technology has recently been adopted and is being used as a bed driving source of, for example, an X-ray CT apparatus. This is because it has an advantage that the control is easier and the size can be reduced as compared with the conventional motor system which is a bed driving source.

By the way, in the X-ray CT apparatus, it is necessary to lower the minimum height in order to make it easier for the patient to get on and off. However, since the mechanism that drives the up and down movement of the bed is a link system, the lower the bed position is when the bed is lowered, the lower the descending speed becomes, which makes it difficult to drive at a constant speed. There is.

Further, in the case where one valve is used in the hydraulic system as the bed driving source, there is a problem that the impact when lowering the bed from the highest position is large and the descending speed is slow.

[Object of the Invention] The present invention has been made in view of the above circumstances, and has a small impact at the time of starting or ending the displacement of a driven body, and a hydraulic drive control device capable of arbitrarily controlling the displacement speed. It is intended to provide.

[Summary of the Invention] An outline of the present invention for achieving the above-mentioned object is to provide a medical bed apparatus for displacing the height of a bed on which a subject is placed by using the pressure of the liquid, in which the flow path of the liquid is A provided pump, a first control means for controlling the operation of the pump, a plurality of valves provided in the liquid flow path, and a height of the bed close to a target position when the bed is displaced. Therefore, a second control means for sequentially controlling the plurality of valves is provided, the displacement speed of the bed is controlled by the first control means, and the displacement speed of the bed is reduced by the second control means. It is characterized by.

[Embodiment of the Invention] A case in which an embodiment of the present invention is applied to drive control of a bed of an X-ray CT apparatus will be described below.

FIG. 1 is a schematic view of a bed 1 of an X-ray CT apparatus. The bed 1 is a first and a second that form a link mechanism on a base 2.
It is supported by arms 3, 4 so that it can move up and down.

A hydraulic cylinder 5 constituting an apparatus according to an embodiment of the present invention is attached to the first arm 3, and a driving force by hydraulic pressure is transmitted to the second arm 4 from an end portion of a piston 5a of the driven cylinder. It is designed to control the rise and fall of the bed 1.

FIG. 2 is an explanatory diagram showing a hydraulic system of the embodiment apparatus of the present invention.

This device includes an oil tank 6 for storing oil, a pipe 7 forming an oil flow path, a pump 8, a check valve 12 and the hydraulic cylinder 5 connected to the pipe 7, and a part of the pipe 7. First to third connected in parallel arrangement and controlled to open and close by an electric signal
The valves V _{1 to} V ₃ and the control means (described later) for sending control signals to the _first to third valves V _{1 to} V ₃ respectively. The control means is a power source E as shown in FIG.
And the first to third valves V _{1 to} V ₃ connected in series to the terminals of the first to third valves V _{1 to} V ₃ and electrically connecting the first to _third valves V _{1 to} V ₃ to the power source E, respectively. A switch unit 15 including switches S _{1 to} S _3, an operation switch 9 for starting and stopping the bed 1, a height detection sensor 10 for detecting the height of the bed 1, and a start from the operation switch 9. Alternatively, a control signal is sent to each of the _first to third valve switches S _{1 to} S ₃ based on an operation signal for instructing stop and a detection signal from the height detection sensor 10, and the operation is started or stopped to the pump 8. And a control circuit 11 for sending the signal of.

Next, with reference to a timing chart showing an operation signal shown in FIG. 4 and a relationship between open / closed states of the _first to third valves V _{1 to} V ₃ , an example of the operation of the device having the above-described configuration, and the bed 1
An example will be described in the case of the descending of. In the hydraulic system, the first to third valves V _{1 to} V ₃ are closed and the hydraulic cylinder 5 is closed.
A constant hydraulic pressure P ₀ is applied to the piston 5a of the couch 1 and the bed 1 is assumed to be at the highest position H ₀ at this time. Now, when a start signal is sent to the control circuit 11 by the operation switch 9, the control circuit 11
First, it sends a control signal to the first valve switch S ₁ to turn it on, and also sends an operation start signal to the pump 8. Then, the valve V ₁ is energized to open the oil flow path, and the pump 8 also transports oil. Therefore, the pump 8, the check valve 12, the hydraulic cylinder 5, the first valve V ₁ and the oil tank 6 are connected. Oil flows in the connecting flow path, and the piston 5a of the hydraulic cylinder 5
The hydraulic pressure applied to is from the initial P ₀ to a lower hydraulic pressure P ₁ .

As a result, the bed 1 starts to slowly descend due to gravity. Initial hydraulic pressure P ₀ and hydraulic pressure when the _first valve V ₁ opens
By making the difference from P ₁ small, the impact at the time of starting the lowering of the bed 1 can be made gentle. Then, after a lapse of a certain time, the control circuit 11 sends a control signal to the _second valve switch S ₂ . This also opens the second valve V ₂ ,
The hydraulic pressure applied to the piston 5a of the hydraulic cylinder 5 is the above hydraulic pressure P ₁
The hydraulic pressure P ₂ becomes even lower. For this reason, the bed 1 will accelerate the descending speed.

After a certain period of time, the control circuit 11 turns the third valve V ₃
Sends a control signal a third valve V ₃ is also in the open state and still lower pressure P ₃ of the hydraulic from the hydraulic P ₂ at that time to.
As a result, the lowering speed of the bed 1 becomes faster. From the above-mentioned control circuit 11 to the first to third valve switches S _{1 to} S ₃
The timing of each control signal sent to is determined based on the detection signal from the height detection sensor 10.

Eventually, when the bed 1 descends to the minimum height, H _L ,
The control circuit 11 which has input the detection signal first sends a control signal to the _first valve switch S ₁ again to close the valve V ₁ .
Then, the hydraulic pressure applied to the piston 5a is lowering speed of the return to the hydraulic P ₂ bed 1 is slightly slower. After a certain period of time, the control circuit 11 also sends a control signal to the _second valve switch S ₂ to close the second valve V _{2 as} well. Then, the hydraulic pressure applied to the piston 5a becomes P ₁ , and the descending speed of the bed 1 becomes slower and slower. Then, when the bed 1 is lowered to just before the minimum height H _L , the control circuit 11 that receives the detection signal from the height detection sensor 10 or the operation signal indicating the stop from the operation switch is
A control signal is sent to the valve switch S ₃ of No. ₃ to close the third valve V ₃ and stop the operation of the pump P. As a result, the check valve 12 and the closed first to third valves V ₁ to
The hydraulic pressure applied to the piston 5a by the action of V ₃ returns to the original hydraulic pressure P ₀ , and the bed 1 also stops at the position of the minimum height H _L accurately and with very little impact.

In this way, by controlling the open / closed states of the _first to third valves V _{1 to} V ₃ , it is possible to perform an accurate descending operation while reducing the impact at the time of starting and ending the descending of the bed 1. .

The opening / closing control of the _first to third valves V _{1 to} V ₃ described above can be applied to the case where the bed 1 is lowered at a constant speed. That is, above a certain height of the bed 1, all the _first to third valves V _{1 to} V ₃ are opened to minimize the hydraulic pressure applied to the piston 5a, and when the bed 1 becomes lower than a certain height, for example, First
Only the valve V _{1 of} is closed, and at the next height,
If a detection signal and a control signal are generated so that the valve V ₂ of the bed is also closed, the hydraulic pressure applied to the piston 5a gradually increases, and therefore the descending speed of the bed 1 supported by the link mechanism due to gravity. Can be kept in equilibrium and the bed 1 can be lowered at a constant speed.

Further, within the range of the bed height corresponding to the X-ray imaging area in the X-ray CT apparatus, for example, only the first valve V ₁ is opened and the bed 1 is slowly lowered, and the bed corresponding to the outside of the X-ray imaging area In the height range, if all of the first to third valves V _{1 to} V ₃ are opened to control the lowering speed of the bed 1,
Patient throughput can be improved.

The present invention is not limited to the embodiment described above,
Various modifications are possible within the scope of the gist. For example,
In the above-described embodiment, the case where the lowering of the bed is controlled to be driven has been described, but the same can be applied to the case where the bed is raised.

In addition, by driving the pump with the first to third valves closed to raise the hydraulic pressure applied to the piston to raise the bed, or opening the first to third valves with the pump stopped, It can also be operated to lower the bed. By thus combining the control of the pump and the valve, the height of the bed can be controlled more finely.

Further, not only the bed of the X-ray CT apparatus but also the bed of other medical equipment and various machines for displacing the driven body,
The same applies to a mechanism such as a lifter that moves a load up and down.

Furthermore, in the above-described embodiment, the case where hydraulic pressure is used has been described, but the present invention is not limited to oil and can be similarly applied to a hydraulic drive control device that uses another liquid.

[Effects of the Invention] According to the present invention described in detail above, a hydraulic drive controller capable of reducing the impact at the start or end of displacement of the driven body because the driving force for the driven body can be arbitrarily changed. Can be provided.

Further, since the displacement speed of the driven body can be set arbitrarily, it is possible to provide a hydraulic drive control device having a high application value, which is capable of constant speed driving of the driven body and low speed driving in a predetermined area.

[Brief description of drawings]

FIG. 1 is a front view showing an example of a bed for applying an embodiment of the present invention, FIG. 2 is a hydraulic system diagram showing a hydraulic system of an embodiment apparatus of the present invention, and FIG. 3 is an electric system of the apparatus. And FIG. 4 is a timing chart showing the relationship between the operation signal of the device and the open / closed states of the first to third valves. V _{1 to} V ₃ ... 1st to 3rd valves, 5 ... hydraulic cylinder,
8 ... Pump, 9 ... Operation switch, 10 ... Height detection switch, 11 ... Control circuit, 15 ... Switch section.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-60-8502 (JP, A) JP-A-59-171536 (JP, A) Actual-open Sho-52-33273 (JP, U) Actual-open Sho-57- 31959 (JP, U) Japanese Patent Sho 47-36957 (JP, B1) Actual Public 43-6858 (JP, Y1)

Claims (1)

(57) [Claims] 1. A medical bed apparatus for displacing the height of a bed on which a subject is placed by using the pressure of a liquid, wherein a pump provided in the liquid flow path and the operation of the pump are controlled. First control means, a plurality of valves provided in the liquid flow path, and second control means for sequentially controlling the plurality of valves as the height of the bed approaches a target position when the bed is displaced. And a second control means for controlling the displacement speed of the bed, and a second control means for reducing the displacement speed of the bed.