JPH0148770B2 - - Google Patents

Description

Detailed Description of the Invention [Technical Field] The present invention relates to an air mat for preventing bedsores that occur when lying on the bed during long-term medical treatment, and in particular to an air chamber that expands and contracts with air supplied from an air pump. The present invention relates to a control system for an air mat equipped with an air chamber that blows out air.

[Background Art] To prevent and treat bedsores, it is effective to avoid local pressure on the patient, prevent blood stasis, and dry the affected area. For this purpose, an air mat that expands and contracts and also blows out air has been proposed. By repeatedly inflating and deflating the air pump, local pressure is avoided and blood congestion is prevented, and the affected area is dried by air jets.

By the way, conventional air mats for expanding and contracting and ejecting air are shown in Figs. 4, 5, and 6.
I got what is shown in the figure. In the one shown in Fig. 4, an air pump P is connected via a switching control valve V to an air mat A formed in a shape in which a first air chamber 1 and a second air chamber 2 are alternately engaged. The switching control valve V is configured to alternately feed air into both air chambers 1 and 2, and evacuate air from the other air chamber 2, 1. Both air chambers 1 and 2 are provided with a blowout hole 30 for blowing out air. In other words, air is ejected from the air chambers 1 and 2 which undergo expansion and contraction. However, in this case, when it is possible to control the amount of air blown out according to winter or summer, or according to personal preference or physical condition, it is necessary to control the capacity of the air pump P or the opening/closing angle of the switching control valve V. Therefore, by controlling the amount of ejected air, the pressure of expansion and contraction of both air chambers 1 and 2 also increases and decreases, resulting in a problem that the body pressure dispersion ability decreases.

Further, in the conventional example shown in FIG. 5, in addition to a pair of air chambers 1 and 2 that alternately expand and contract, a third air chamber 3 equipped with an air jet hole 30 is provided, and a switching control valve is provided. A flow rate control valve C placed between V and the air chamber 3 makes it possible to independently control the amount of air ejected. If an attempt is made to reduce the pressure, the pressure of the air supplied to the air chambers 1 and 2 which undergo expansion and contraction increases, resulting in the problem that an appropriate body pressure distribution pressure cannot be obtained.

Furthermore, in the embodiment shown in FIG. 6, air chamber 1 and air chamber 2 are
A third air chamber 3 is disposed over the entire upper surface of both the air chamber 3 and the air chamber 3 is provided with an air outlet 30.
, air pump P to which both air chambers 1 and 2 are connected
It is connected to an air pump P' that is separate from the air chamber P', and the pressure in air chambers 1 and 2 is completely independent of the amount of air ejected from air chamber 3, thereby controlling the amount of air ejected. This eliminates the possibility that the pressure in the air chambers 1 and 2 changes. However, in this case, two air pumps P and P' are required, and problems remain in terms of cost and size.

[Object of the Invention] The present invention has been made in view of the above points, and its purpose is to constantly supply air at an appropriate pressure to an air chamber that can be expanded and deflated to change the body weight support position. To provide a control system for an air mat that can realize free adjustment of the amount of air jetted out at low cost at the same time as the air mat.

[Disclosure of the Invention] Accordingly, the present invention provides a switching control valve between the air chamber of the air mat which can be expanded and deflated and the air pump, and a switching control valve between the air chamber of the air mat that is equipped with an air jet hole and the air pump. By installing a flow control valve,
When supplying air from the air pump to each air chamber via the supply switching control valve or flow control valve, the pressure of the air sent to the air chamber, which can expand and contract freely, is monitored, and the air discharge from the air pump is adjusted according to this monitoring output. The main idea is to adjust the capacity, and the amount of air jetted from the air jet hole can be adjusted by operating a flow rate control valve, and at this time, the air pressure sent to the air chamber, which can be expanded and contracted, can be changed. This is characterized in that this is prevented by adjusting the air discharge capacity of the air pump.

The present invention will be described below in detail based on the illustrated embodiment. As shown in FIG. Since the air chamber 3 is provided along the air chamber 3, a large number of minute air ejection holes 30 are provided in the air chamber 3. The other ends of the air chambers 1 and 2 are respectively connected to switching control valves V as electromagnetic three-way valves.
The air chamber 3 is connected to the air pump P via a flow control valve C.

Here, a pressure sensor S for detecting air pressure is installed between the discharge part of the air pump P and the branch part to the pair of switching control valves V, V and the flow control valve C, and a phase control circuit A pressure sensor S is connected to the comparison circuit 6 of a control circuit consisting of a comparison circuit 5, a comparison circuit 6, a timer circuit 7, and a voltage circuit 8. The timer circuit 7 alternately switches the two switching control valves V and V at predetermined time intervals to alternately connect the air pump P and the air chambers 1 and 2 and alternately open the air chambers 1 and 2 to the atmosphere. In other words, the air chambers 1 and 2 are caused to expand and contract alternately. The phase control circuit 5 is
According to the output of the comparator circuit 6, the phase of the conduction angle of the current supplied to the motor in the air pump P is controlled to adjust the air discharge capacity of the air pump P.
As mentioned above, the comparison circuit 6 compares the output voltage of the pressure sensor S with the reference voltage set by the pressure value setting volume. If the detected air pressure becomes low, the air discharge capacity of the air pump P is increased via the phase control circuit 5, and if the air pressure detected by the pressure sensor S becomes high, the air discharge capacity of the air pump P is increased via the phase control circuit 5. reduce ability.

Next, the operation will be explained in detail based on FIGS. 2 and 3. Now, the air discharge capacity (pressure-air amount characteristic) of the air pump P is in the state shown by V ₁ in Fig. 2, and the air pump A including the flow rate control valve C, etc.
When the overall load characteristic (air quantity-pressure characteristic) of is in the state shown by _M1 , it means that the engine is operated under the condition of intersection A of both characteristic curves, that is, under the condition of pressure value ₁ and air quantity _Q1 .

If the flow control valve C is opened from this state in order to increase the amount of air ejected from the air ejection hole 30, the total load characteristic curve will normally be as indicated by M ₂ ' in the figure, and this characteristic curve M ₂ The air pressure is reduced and the air amount is increased until the pressure value P ₂ ′ and air amount Q ₂ are reached as indicated by the intersection point B ′ between ′ and the characteristic curve V ₁ . The pressure sensor S that has detected , via the comparison circuit 6 and the phase control circuit 5, increases the air discharge capacity of the air pump P so that its characteristic curve is indicated by V ₂ in the figure.
As a result, while securing the air amount _Q2 , the air pressure is maintained at the pressure value _P1 , which is the initial setting pressure suitable for distributing and supporting the weight in the air chambers 1 and 2. Note that this adjustment is instantaneous, and therefore, the adjustment operation of the flow control valve C changes the total load curve from M ₁ in the figure.
It is not necessary to carry out the procedure until M ₂ ' is reached, and it is sufficient to simply open the flow rate control valve C until the total load curve shown by M ₂ is reached.

Conversely, if the flow rate control valve C is throttled to reduce the amount of air ejected from the air ejection holes 30, the overall load characteristic curve would normally be as indicated by _M3 ' in the figure, and this characteristic curve M3 The air pressure is increased and the air amount is decreased until the pressure value P ₃ ′ and the air amount Q ₃ are reached as indicated by the intersection point C ′ between ′ and the characteristic curve V ₁ . The pressure sensor S, which has detected the increase, uses the comparison circuit 6 and the phase control circuit 5 to lower the air discharge capacity of the air pump P so that its characteristic curve is indicated by _V3 in the figure.
As a result, while securing the air amount _Q3 , the air pressure is maintained at the pressure value _P1 , which is the initial setting pressure suitable for distributing and supporting the weight in the air chambers 1 and 2. In this case, it is not necessary to adjust the flow rate control valve C until the total load curve changes from M ₁ to M ₃ ' in the figure, and M ₃
It is only necessary to throttle the flow rate control valve C until the total load curve shown by is achieved.

In other words, the air discharge capacity of the air pump is adjusted by controlling the phase of the conduction angle in response to changes in the overall load characteristics due to the adjustment of the amount of air blown out, and the amount of air is supplied in accordance with the amount of air blown out. at the same time,
The air pressure is maintained at a constant value suitable for weight distribution support. FIG. 3 shows the voltage waveforms applied to the air pump P when the characteristic curves of the air pump P are V ₁ , V ₂ , V ₃ and Vmax.
Note that Vmax is a characteristic curve of the air pump P when the flow rate control valve C is fully closed.

[Effects of the Invention] As described above, in the present invention, the pressure of the air sent to the expandable and deflated air chamber is monitored, and the flow rate adjustment is performed in order to adjust the air discharge capacity of the air pump according to the monitored output. Even if the amount of air jetted from the air jet hole is adjusted by operating the valve, the air pressure sent to the air chamber, which can expand and contract, remains at a constant value by adjusting the air pump's air discharge capacity. Therefore, it is possible to constantly supply air at the appropriate pressure to the air chamber, which can expand and contract freely to change the weight support position, without having to prepare multiple air pumps, at a low cost. It is something. Furthermore, it has the advantage that even if a pinhole occurs in the air mat or there are variations in the pressure characteristics of the air pump, the pressure is automatically controlled to a constant pressure.

[Brief explanation of drawings]

Fig. 1 is a block circuit diagram of an embodiment of the present invention, Fig. 2 is a characteristic diagram showing the same effect as above, Fig. 3 is a voltage waveform diagram, and Figs. 4 to 6 are block circuit diagrams of conventional examples. , A is an air mat, C is a flow control valve, P is an air pump, S is a pressure sensor,
1 and 2 are air chambers that can be expanded and contracted, 3 is an air chamber equipped with an air jet hole, 5 is a phase control circuit, 6 is a comparison circuit,
30 indicates an air outlet.

Claims (1)

[Claims] 1. A switching control valve is disposed between the air chamber of the air mat which can be expanded and deflated and the air pump, and a flow rate control valve is disposed between the air chamber of the air mat having an air jet hole and the air pump. When supplying air to each air chamber via the supply switching control valve or flow control valve, the pressure of the air sent to the air chamber, which can expand and contract freely, is monitored, and the air pump's air discharge capacity is adjusted according to the monitored output. A control method for an air mat characterized by adjusting.