Pressure relief valve for blood pressure measuring instrument

A pressure relief valve for a blood pressure measuring instrument which is provided with a discharge mechanism for selectively discharging a small or large amount of compressed air. The discharge mechanism of simple structure is constituted from a small number of members including a valve member, a spring, an adjustment screw plug and a push button. A cuff pressure is automatically reduced at the predetermined reducing rate by rotating the adjustment screw plug during the measurement of blood pressure. Pushing of the push button also makes it possible to discharge at once the remaining cuff pressure after the measurement of blood pressure.

FIELD OF THE INVENTION 
The present invention relates to an improved cuff pressure relief valve for 
blood pressure measuring instrument of the type, in which the highest and 
lowest blood pressure are measured by way of gradually reducing air 
pressure in a rubber bulb to detect appearing and disappearing of blood 
vessel noise in the course of the said pressure reducing, after 
pressurizing air in the cuff wrapped round an operator by means of the 
rubber bulb repeatedly manually grasped and depressed. 
DESCRIPTION OF THE PRIOR ART 
Generally there is specified a cuff pressure reducing rate. Usually 2 to 4 
mHg/pulse is preferred as an ideal range of cuff pressure reducing rate 
during blood pressure measuring. It has been hitherto pointed out that an 
average man (particularly old man, high blood pressure patient) can't 
operate easily any prior art of blood pressure measuring instrument by way 
of continuous valve controlling at his home without any assistance by 
other person or in the absence of doctor. 
SUMMARY OF THE INVENTION 
The present invention is proposed to eliminate the drawbacks with the 
hitherto known blood pressure measuring instrument as mentioned above. In 
accordance with the present invention there is provided a pressure relief 
valve for blood pressure measuring instrument, in which the most 
preferable cuff pressure reducing rate is ensured only by releasing the 
rubber bulb, after pressurized air in the cuff to the predetermined height 
of pressure and further quick cuff pressure relieving is effected by way 
of push button operation after completion of blood pressure measuring. The 
pressure relief valve according to the present invention includes a single 
plug shaped valve member and a single push button to actuate the same, 
which are operative for a discharge mechanism. Owing to the arrangement as 
described above, the pressure relief valve is constructed in a more simple 
way. 
It is a principal object of the present invention to provide a pressure 
relief valve for blood pressure measuring instrument, in which fine and 
quick pressure relieving is carried out with a single valve arrangement 
without any additional adjustment thereon in the course of blood pressure 
measuring. 
It is a further object of the present invention to provide a pressure 
relief valve for blood pressure measuring instrument, which is simple in 
the structure and very inexpensive to be manufactured. 
It is a further object of the present invention to provide a pressure 
relief valve for blood pressure measuring instrument, which is very easy 
to be operated by any average man, particularly old man, high blood 
pressure patient etc. 
Other objects and advantageous features of the invention will be apparent 
from the description and claims.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
As shown in FIG. 1, the reference numeral 1 denotes a square block shaped 
valve housing, which is provided with mushroom shaped connectors 3 and 4 
at its front and rear ends respectively. The said connector 3 is connected 
to the rear end of a rubber tube 5 which is in communication with a cuff 
(not shown), while the said connector is connected to the front end of a 
rubber bulb 6. On the upper and lower portions of the housing 1 are formed 
circular recesses 7 and 8 respectively, the said circular recess 7 being 
adapted to receive therein the head of a cap shaped screw plug 9 to be 
screwed in the valve housing 1, while the said circular recess 8 being 
adapted to receive therein an adjustment screw plug in such a manner that 
it is freely rotated. The reference numeral 11 denotes two exhaust holes 
located symmetrically on the both sides of the center axis of the screw 
plug 10. The screw cap 9 and screw plug 10 are disposed to cross an air 
passage 2 of the valve housing at a substantially right angle. The 
reference numeral 12 denotes a push button which is arranged vertically 
displaceablly along the center axis of the said screw plug 10. The push 
button 12 is supported in the hollow space of the screw plug 10 by way of 
engagement of the upper surface of the stepped portion 13 of the same to 
the lower surface of the stepped portion 14 of the push button 12, wherein 
the head thereof is protruded outside the screw plug 10. The reference 
numeral 15 denotes a plug shaped valve member which is disposed in the 
valve housing at a substantially right angle to the air passage 2. The 
valve seat of the said valve member 15 is formed by an outwardly 
converging taper hole 16 itself, which has a through opening for serving 
to communicate the air passage in the valve housing with the outside 
atmosphere, while the head of the valve member is protruded into the 
outside of the valve housing (i.e. within the said recess 8) to come in 
contact with the backside of the push button. The reference numeral 17 
denotes a valve closing spring which is arranged to be spanned between the 
bottom of circular recess 18 of the screw cap 9 and the upper surface of 
the valve member 15. Further the reference numeral 19 denotes a stopping 
spring which is also inserted between the adjustment plug 10 and the 
bottom surface of the said circular recess 8. Owing to the arrangement of 
the said resilient means 19, the adjustment plug can be kept fixed in the 
screw engagement position. It is to be noted that as the adjustment plug 
is further screwed in to open the valve member, the resilient force of the 
spring 17 acts increasingly on the upper surface of the adjustment plug 
and the screw engagement of the both members 1 and 10, resulting in 
increased screw engagement and immovability therebetween. The reference 
numeral 20 denotes a well known check valve of rubber material disposed in 
the air passage 2, the reference numeral 21 does slits formed on the side 
wall of the said check valve 20 and the reference numeral 22 does a 
filter. 
Now the pressure regulating and relieving valve in accordance with the 
present invention is adjusted in the following manner; The adjustment plug 
10 is screwed in or out with the aid of a spanner which is specially 
designed for this valve of the invention to fit into the exhaust holes 11, 
so as to ensure the required opening of the valve member 15 so that the 
cuff pressure is decreased at the specified rate during measuring. Once 
the said valve opening is predetermined, no additional adjustment is 
required. An operator can always lower the cuff pressure at the specified 
rate of pressure reducing only by releasing the rubber bulb, after 
increasing the cuff pressure to the required height by way of depressing 
the rubber bulb, while he can exactly measure the highest and lowest blood 
pressure. As the stopping spring 19 acts always against the adjustment 
plug in the downward direction, the said adjustment plug is remained fixed 
with the push button held thereon during measuring. After measuring, quick 
release of the residual cuff pressure is carried out only by depressing 
the push button with the use of his finger, while he is grasping the 
rubber bulb. It will be obvious that pressurized air in the passage 2 is 
discharged through the tapered hole 16 and the clearance between the inner 
wall of the recess 8 and the adjustment plug 10 and through the exhaust 
holes 11. 
As described above, present invention lies in that the pressure relief 
valve comprizes a single plug shaped valve member and a single push button 
in such a simple construction that has never been hitherto achieved, 
causing the cuff pressure to be automatically reduced at the specified 
pressure reducing rate without any valve operation during measuring and 
moreover the resultant cuff pressure to be released by way of valve 
operation using a push button. It, therefore can be concluded that the 
present invention has brought about a remarkable improvement with such 
kind of pressure relief valve. 
It should, of course, be understood that the description and drawings 
herein are illustrative merely and a variety of modifications and changes 
can be made in the structure as disclosed above without any departure from 
the spirit of the invention.