The present invention relates to a pressure detecting apparatus for detecting fluid pressure by converting the fluid pressure into a displacement of a pressure-receiving member and particularly relates to a pressure detecting apparatus adapted for detection of differential pressure between fluid chambers.
In the background art, there is a pressure detecting apparatus in which fluid pressure is converted into a displacement of a pressure-receiving member to thereby ensure detection accuracy and the apparatus is made adapted to a required environmental condition in use. In a remarkably changeable condition such as that of an aircraft flight control system requiring high reliability in a wide temperature range, the pressure detecting apparatus of this type is used versatilely because it is practically difficult to use a general pressure sensor for detecting differential pressure while satisfying such a requirement for reliability.
FIG. 3 is a view showing the pressure detecting apparatus of this type in the background art. The pressure detecting apparatus is formed as a differential pressure detecting apparatus. In the apparatus, two oil pressures from two oil chambers 2A and 2B in a housing 1 are received by a slidable pressure-receiving shaft member 3 from its axially opposite end sides. As a result, the pressure-receiving shaft member 3 is axially displaced due to difference between the two values of pressure received by the pressure-receiving shaft member 3. Thus, the displacement of the pressure-receiving shaft member 3 is detected by a highly reliable LVDT (differential transformer) 4.
In the background-art pressure detecting apparatus, however, coiled spring type urging means 5A and 5B for urging the pressure-receiving shaft member 3 toward a neutral position were provided on opposite sides which were in the housing 1 and on the same axial line as that of the pressure-receiving member 3. The urging means 5A and 5B were complex and high in cost because they contained a large number of parts such as spring seats, etc. Moreover, the LVDT 4 was disposed in an apparatus end portion in the axial direction of the pressure-receiving shaft member 3 because of the necessity for ensuring the required spring characteristic. Hence, the apparatus size in the direction of the axial length of the pressure-receiving shaft member 3 was increased. There was a problem that it was difficult to reduce the size of the apparatus.
Moreover, there was a possibility that differential pressure might be detected inaccurately because spring seat portions and coiled springs constituting the urging members 5A and 5B abutted against the inner wall of the housing. There was also a problem in reliability.
Such problems were more remarkable in the case where a pair of pressure detecting apparatuses not prepared for detection of differential pressure were used for detecting differential pressure between a pair of fluid chambers. Even in the aforementioned pressure detecting apparatus used singly, the same problem as described above still occurred because the aforementioned coiled spring type urging means were used in the apparatus.
Therefore, an object of the present invention is to provide a pressure detecting apparatus easily reduced in size and high in reliability.
In order to achieve the above object, according to the present invention, there is provided a pressure detecting apparatus comprising: a housing forming at least one fluid chamber into which external fluid pressure is imported; a pressure-receiving member slidably provided in the housing so that the pressure-receiving member moves when the pressure-receiving member receives the fluid pressure in the fluid chamber; an elastic member supported by the housing and engaged with the pressure-receiving member so that the elastic member is elastically deformed due to a slide displacement of the pressure-receiving member from a predetermined position; a displacement detecting system which detects the displacement of the pressure-receiving member from the predetermined position; and the elastic member including a base portion supported by the housing, an engagement portion engaged with the pressure-receiving member, and a flexible arm extending from the base portion toward the engagement portion along a plane approximately perpendicular to a direction of sliding of the pressure-receiving member.
According to this aspect of the present invention, the elastic member includes a flexible arm extending along a plane approximately perpendicular to the direction of sliding of the pressure-receiving member. Hence, urging means such as elastic members for making the pressure-receiving member displaced due to the received pressure and for generating restoring force to a predetermined position from the displacement of the pressure-receiving member need not be disposed on one side or opposite sides in the direction of sliding of the pressure-receiving member. Hence, the apparatus length in the direction of sliding of the pressure-receiving member can be shortened, so that the size of the apparatus can be reduced easily. Moreover, there is no fear that such an elastic member for urging the pressure-receiving member may slidably abut against the inner wall of the housing. Hence, pressure detection accuracy is not spoiled, so that reliability becomes high.
Incidentally, the flexible arm extending along a plane approximately perpendicular to the direction of sliding of the pressure-receiving member means a flexible arm along a plane approximately perpendicular to the sliding direction. The flexible arm need not be straight, and maybe curved. The flexible arm may be a plate-like elastic material, but is not limited thereto. The direction of sliding of the pressure-receiving member need not be linear but may be curved circumferentially.
According to the present invention, there is further provided a pressure detecting apparatus for detecting differential pressure between two fluid chambers into which fluids are imported respectively, the apparatus comprising: a housing for forming the two fluid chambers; a pressure-receiving member provided slidably in the housing so that the pressure-receiving member moves from one of the fluid chambers to the other of the fluid chambers due to differential pressure between the two fluid chambers; an elastic member supported by the housing and engaged with the pressure-receiving member so as to be elastically deformed due to a slide displacement, of the pressure-receiving member, from a predetermined position; a displacement detecting means for detecting the displacement of the pressure-receiving member, from the predetermined position; and the elastic member including a base portion supported by the housing, an engagement portion engaged with the pressure-receiving member, and a flexible arm extending from the base portion toward the engagement portion along a plane approximately perpendicular to a direction of sliding of the pressure-receiving member.
According to this aspect of the present invention, the elastic member includes a flexible arm extending along a plane approximately perpendicular to the direction of sliding of the pressure-receiving member. Hence, the elastic members for making the pressure-receiving member displaced due to the received pressure and for generating restoring force to a predetermined position from the displacement of the pressure-receiving member need not be disposed on opposite sides in the direction of sliding of the pressure-receiving member. Hence, the apparatus length in the direction of sliding of the pressure-receiving member can be shortened on a large scale, so that the size of the apparatus can be reduced easily. Moreover, there is no fear that such an elastic member for urging the pressure-receiving member may slidably abut against the inner wall of the housing. Hence, differential pressure detection accuracy is not spoiled, so that reliability becomes high.
Preferably, the elastic member includes an eddy-like flexible arm extending from the base portion to the engagement portion. Further preferably, the elastic member includes a plurality of eddy-like flexible arms eddying in one and the same direction with the base portion as two ends, the plurality of flexible arms being connected to one another at the engagement portion.
More preferably, the pressure detecting apparatus is configured so that the elastic member is made of a leaf spring supported by the housing in an outer circumferential portion. According to this configuration, the elastic member can be produced easily. Further, when the elastic member is supported by the housing in one of the fluid chambers, the pressure detecting apparatus can be small-sized further preferably. It is a matter of course that the elastic member may be disposed in the housing but in an inner space separated from the fluid chambers.
The present disclosure relates to the subject matter contained in Japanese patent application No. 2000-103262 (filed on Apr. 5, 2000), which is expressly incorporated herein by reference in its entirety.