Pressure measuring device

Abstract

Pressure measuring device (100), comprising: a cylinder (110) comprising an air connection (111); a piston (120) which is movably arranged in the cylinder (110) along a first axis (A1), wherein the piston (120) comprises a first end (121) and a second end (122) which are opposite each other, and a rack (124) which is located between the first end (121) and the second end (122) and extends along the first axis (A1), wherein the first end (121) is located next to the air port (111); an elastic element (130) which is arranged in the cylinder (110) and rests against the second end (122) of the piston (120); a rotary shaft (140) rotatably arranged along a second axis (A2) in the cylinder (110), wherein the rotary shaft (140) comprises ring teeth (143) located in the cylinder (110) and an end (145) projecting out of the cylinder (110), the ring teeth (143) engaging with the rack (124); a scale (150) located outside the cylinder (110), wherein the end (145) of the rotating shaft (140) passes through a center point of the scale (150); and a pointer (160) which is connected to the end (145) of the rotating shaft (140) and is located above the scale (150), wherein, when a gas from the air inlet (111) enters the cylinder (110), the piston (120) is pushed to move along the first axis (A1), so that the elastic element (130) is compressed and the rack (124) of the piston (120) drives the rotating shaft (140) to rotate along the second axis (A2), so that the pointer (160) rotates relative to the scale (150) to indicate a corresponding air pressure value.

Description

BACKGROUND OF THE INVENTION Area of ​​the invention

[0001] The invention relates to a pressure measuring device, in particular a pressure measuring device that can display the air pressure more accurately. Description of the state of the art

[0002] Conventional mechanical pressure gauges use a Baden tube design, where the tube's bending deformation drives the gear set and pointer to indicate pressure. This complex mechanism is prone to damage, and the Baden tube's load-deformation ratio curve is nonlinear, making it difficult to achieve a stable and precise mechanical action for displaying the correct pressure. Providing a pressure gauge capable of more accurately indicating atmospheric pressure is an area of ​​research in this field. BRIEF SUMMARY OF THE INVENTION

[0003] The invention provides a pressure measuring device that can display the air pressure more accurately.

[0004] The invention provides a pressure measuring device comprising a cylinder, a piston, an elastic element, a rotating shaft, a scale, and a pointer. The cylinder includes an air connection. The piston is movably arranged within the cylinder along a first axis. The piston has a first end and a second end, opposite each other, and a rack located between the first and second ends and extending along the first axis. The first end is located next to the air connection. The elastic element is arranged within the cylinder and rests against the second end of the piston. The rotating shaft is rotatably arranged within the cylinder along a second axis. The rotating shaft has annularly arranged teeth located within the cylinder and an end projecting from the cylinder, the annular teeth engaging with the rack.The scale is located outside the cylinder, and the end of the rotating shaft passes through the center of the scale. The pointer is connected to the end of the rotating shaft and is positioned above the scale. When gas enters the cylinder from the air inlet, the piston is pushed and moves along the first axis, compressing the elastic element. The piston's rack drives the rotating shaft to rotate along the second axis, causing the pointer to turn relative to the scale to indicate the corresponding air pressure reading.

[0005] In one embodiment of the invention, the piston includes a limiting element located between the first end and the second end, wherein the rack faces the limiting element and a through groove is located between the rack and the limiting element, wherein the rotary shaft is arranged in the through groove and the limiting element rests against the rotary shaft, so that the ring teeth of the rotary shaft are continuously engaged with the rack during a movement of the piston.

[0006] In one embodiment of the invention, the cylinder includes a first through-hole and a second through-hole, and the rotating shaft includes a cap, a first section, the annular teeth, a second section, and the end, arranged sequentially. The cap is located outside the cylinder, and its size is larger than that of the first through-hole. The first section is located in the first through-hole, and its limiting element abuts the first section of the rotating shaft. The second section is located in the second through-hole, and its end is smaller than that of the second through-hole.

[0007] In one embodiment of the invention, the second end of the piston has a shape that is a combination of an arc and a secant, and there is a platform. The cylinder has a plane that corresponds to the platform within it, so that the piston moves only along the first axis in the cylinder.

[0008] In one embodiment of the invention, the pressure measuring device further comprises a cover, wherein the cylinder has an opening away from the air connection, the cover is screwed onto the cylinder to close the opening, the elastic element rests between the cover and the second end of the piston, and the depth of the cover screwed onto the cylinder is adjusted to set a compression level of the elastic element. The cover is provided with a triangular adjustment hole at the center-axis position of an outer surface to facilitate the use of a correspondingly shaped key to rotate the cover manually or by automated devices to adjust the degree of compression of an elastic body.

[0009] In one embodiment of the invention, the pressure measuring device further comprises a housing which is connected to the cylinder and is located between the cylinder and the scale, wherein the rotating shaft passes through the housing and the scale is detachably arranged on the housing.

[0010] In one embodiment of the invention, the housing includes a regular polygonal central locking mechanism (in one example of the description, a regular square) and the scale includes a regular polygonal central hole corresponding to the central locking mechanism.

[0011] In one embodiment of the invention, the housing and the cylinder are integrated.

[0012] In one embodiment of the invention, the pressure measuring device further comprises a sealing ring which is adapted to the first end of the piston and bears against an inner wall surface of the cylinder, wherein a cross-section of the sealing ring is circular.

[0013] In one embodiment of the invention, the pressure measuring device further comprises an air nozzle and a buckle, wherein the air nozzle is arranged protruding on the cylinder and connected to the air connection, and the buckle is arranged next to the air nozzle to connect an air pressure device to be tested.

[0014] Based on the foregoing, the piston of the pressure measuring device of the invention includes the rack extending along the first axis. The elastic element is arranged in the cylinder and rests against the second end of the piston. The rotating shaft is rotatably arranged in the cylinder along the second axis, and the ring teeth of the rotating shaft engage with the rack. The scale is located outside the cylinder, and the end of the rotating shaft passes through the center of the scale. The pointer is connected to the end of the rotating shaft and is positioned above the scale. Thus, when gas enters the cylinder from the air inlet, the piston is moved along the first axis, compressing the elastic element. The piston's rack drives the rotating shaft to rotate along the second axis, causing the pointer to rotate relative to the scale to indicate the corresponding air pressure reading.Since the elastic element has the shape of a cylindrical compression spring, its load / deformation ratio curve is a straight line. Combined with the precise transmission of the rack and pinion, the mechanical conversion error is extremely low, resulting in a precise air pressure reading. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 and Fig. Figure 2 shows schematic views of a pressure measuring device according to an embodiment of the invention from different perspectives. Fig. Figure 3 is a schematic exploded view of the pressure measuring device made of Fig. 1. Fig. Figure 4 is a schematic exploded view of some elements of the pressure measuring device. Fig. 1 from a different perspective. Fig. Figure 5 is a perspective sectional view of the pressure measuring device made of Fig. 1. Fig. Figure 6 is a top view of another cross-section of the pressure measuring device made of Fig. 1. Fig. Figure 7 is a schematic view of a piston of the pressure measuring device. Fig. 1. Fig. Figure 8 is a partial sectional view of the pressure measuring device made of Fig. 1. DESCRIPTION OF THE EXECUTION FORMS

[0015] Fig. 1 and Fig. Figure 2 shows schematic views of a pressure measuring device according to an embodiment of the invention from different perspectives. See Fig. 1 and Fig. 2. A pressure measuring device 100 of the present embodiment is used to connect an air pressure device to be tested (not shown, for example, a tire, but not limited to) and can accurately measure the air pressure value of the air pressure device under test. This is explained in detail below.

[0016] Fig. Figure 3 is a schematic exploded view of the pressure measuring device made of Fig. 1. Fig. Figure 4 is a schematic exploded view of some elements of the pressure measuring device. Fig. 1 from a different perspective. Fig. Figure 5 is a perspective sectional view of the pressure measuring device made of Fig. 1. Fig. Figure 6 is a top view of another cross-section of the pressure measuring device made of Fig. 1. Fig. Figure 7 is a schematic view of a piston of the pressure measuring device. Fig. 1. Fig. Figure 8 is a partial sectional view of the pressure measuring device made of Fig. 1.

[0017] With reference to the Fig. 3 to 8 the pressure measuring device 100 of the present embodiment includes a cylinder 110, a piston 120, an elastic element 130, a cover 185, a rotating shaft 140, a scale 150 and a pointer 160.

[0018] As in Fig. As shown in Figure 6, cylinder 110 contains an air connection 111 (in Fig. 6 arranged on the left side of the cylinder 110) and an opening 115 (in Fig. 6 arranged on the right side of the cylinder 110) relative to each other with respect to a second axis A2 and a first through-hole 112 (in Fig. 6 arranged at the bottom of the cylinder 110) and a second through-hole 113 (in Fig. 6 arranged at the upper end of the cylinder 110) relative to each other with respect to a first axis A1.

[0019] As in Fig. 6 and Fig. As shown in Figure 7, the piston 120 is movably arranged in the cylinder 110 along the first axis A1. The piston 120 comprises a first end 121, a second end 122, and a rack 124 located between the first end 121 and the second end 122, extending along the first axis A1. The first end 121 of the piston 120 is located next to the air port 111.

[0020] As in Fig. 7 and Fig. As shown in Figure 8, the piston 120 also includes a limiting element 125 located between the first end 121 and the second end 122, wherein the rack 124 is opposite the limiting element 125 and a through groove 126 is located between the rack 124 and the limiting element 125.

[0021] As in Fig. 3 and Fig. As shown in Figure 6, the rotary shaft 140 is rotatably arranged in the cylinder 110 along the second axis A2 and is positioned in the through groove 126. The rotary shaft 140 is connected to the pointer 160.

[0022] The rotating shaft 140 comprises a cap 141, a first section 142, ring teeth 143, a second section 144, and an end 145, arranged sequentially. The ring teeth 143 are located inside the cylinder 110, and the end 145 and the cap 141 are located outside the cylinder 110. The cap 141 is larger than the first through-hole 112 of the cylinder 110, and the first section 142 is located in the first through-hole 112. The second section 144 is located in the second through-hole 113.

[0023] The pressure measuring device 100 of the present embodiment can mechanically convert the linear movement of the piston 120 into the rotation of the pointer 160 via the interaction between the rack 124 and the ring teeth 143.

[0024] As in Fig. As shown in Figure 8, the limiting element 125 rests against the first section 142 of the rotary shaft 140, and the ring teeth 143 engage with the rack 124. The limiting element 125 rests against the rotary shaft 140 so that the ring teeth 143 of the rotary shaft 140 remain continuously engaged with the rack 124 during the movement of the piston 120. In this way, the movement of the piston 120 can precisely convert the rotation of the ring teeth 143 of the rotary shaft 140 to prevent the ring teeth 143 from disengaging from the rack 124, which would prevent the rack 124 from fully driving the ring teeth 143.

[0025] In particular, in the present embodiment, the cross-section of the limiting element 125 is V-shaped. Due to the V-shaped cross-sectional design of the limiting element 125, the limiting element 125 has improved structural strength, and the limiting element 125 generates counter-pressure when the ring teeth 143 are pressed, so that the ring teeth 143 lie close to the rack 124 in order to more effectively prevent the ring teeth 143 from separating from the rack 124 or from the ring teeth 143 wobbling during rotation due to the gap between the rack 124 and the ring teeth 143, which would cause the pointer 160 to oscillate unintentionally.

[0026] Furthermore, the second end 122 of the piston 120, as in Fig. Figure 4 shows a shape that is a combination of an arc and a secant, and a platform 123 is provided there. The cylinder 110 contains a plane 114 that corresponds to the platform 123 within it, in order to prevent the piston 120 from rotating and affecting the engagement state between the rack 124 and the ring teeth 143 when the piston 120 moves along the first axis A1 in the cylinder 110.

[0027] With reference to Fig. The pressure measuring device 100 further includes a sealing ring 180, which is adapted to the first end 121 of the piston 120 and bears against an inner wall surface 116 of the cylinder 110. The sealing ring 180 maintains a tight fit with the inner wall surface 116 of the cylinder 110 and can move within the cylinder 110 together with the piston 120. The pressure measuring device 100 defines a pressure chamber between the first end 121 of the piston 120 and the air port 111, which is delimited by the sealing ring 180.

[0028] The sealing ring 180 of the present embodiment has a circular cross-section, so that when the piston 120 moves along the first axis A1 from Fig. 6 to the left and right, the contact area between the sealing ring 180 and the cylinder 110 remains the same and the frictional force between the piston 120 and the inner wall surface 116 of the cylinder 110 remains the same when the piston 120 moves forward and backward along the first axis A1.

[0029] Furthermore, the pressure measuring device 100 includes a cover 185. The cover 185 is screwed onto the cylinder 110 to close the opening 115 of the cylinder 110. The elastic element 130 is arranged in the cylinder 110 and rests between the cover 185 and the second end 122 of the piston 120. In the present embodiment, the elastic element 130 is, for example, a compression spring.

[0030] Furthermore, as in Fig. Figure 3 shows the scale 150 outside the cylinder 110, and the end 145 of the rotating shaft 140 passes through a central hole 151 of the scale 150. The scale 150 is a disc-shaped object with a thickness ranging from several micrometers to several millimeters. The surface of the scale 150 is printed or engraved with numbers representing the air pressure value and the symbol for the air pressure unit.

[0031] The pointer 160 is connected to the end 145 of the rotating shaft 140 and is located above the scale 150. The end 145 of the rotating shaft 140 is inserted into a hole 161 of the pointer 160 and firmly fitted therein, and a tip 162 of the pointer 160 can rotate around the end 145 to indicate the air pressure value on the scale 150.

[0032] In the present embodiment, the degree of compression of the elastic element 130 can be adjusted by changing the depth of the cover 185 screwed onto the cylinder 110, thus calibrating the pointer 160 to its initial value. Specifically, the cover 185 has an internal thread 186, and the cylinder 110 has an external thread 117 near the opening 115. The internal thread 186 of the cover 185 is screwed into the external thread 117 of the cylinder 110. By rotating the cover 185, its position relative to the cylinder 110 can be changed, thereby adjusting the compressed length of the elastic element 130 and thus changing the position of the piston 120 to adjust the angle of the rotating shaft 140 and the pointer 160.The cover 185 is provided with a triangular adjustment hole 187 at the central axis position of an outer surface to facilitate the use of a key of appropriate shape to rotate the cover 185 manually or by automated devices to adjust the degree of compression of an elastic body 130.

[0033] Furthermore, the pressure measuring device 100 includes an air nozzle 190 and a buckle 195. The air nozzle 190 is arranged protruding from the cylinder 110 and connects the air port 111 ( Fig. 6) with the pressure chamber. The buckle 195 is arranged next to the air nozzle 190 to establish a connection to an air pressure device under test (not shown, for example, a tire, but not limited to). A sealing ring 182 is provided on the air nozzle 190. When the buckle 195 is connected to the air pressure device under test, the air nozzle 190 is inserted into the connection hole of the air pressure device under test, and the sealing ring 182 is pressed against the inner wall surface of the connection hole of the air pressure device under test to maintain the airtightness of the connection between the air nozzle 190 and the air pressure device under test.

[0034] In its initial setting state, the tip 162 of the pointer 160 is preset above the atmospheric pressure value of 0 (initial value) on the scale 150. The air nozzle 190 is connected to the pressure chamber, so that when the air nozzle 190 is connected to the air pressure device under test, the pressure in the pressure chamber and in the air pressure device under test changes synchronously. When the atmospheric pressure of the air pressure device under test is greater than atmospheric pressure, gas flows from the air inlet 111 into the cylinder 110. The atmospheric pressure exerts a thrust on the piston 120, pushing the piston 120 along the first axis A1. At this point, the elastic element 130 is forced through the second end 122 of the piston 120, compressed, and deformed.The compressed and deformed elastic element 130 then exerts a reverse elastic force on the second end 122 of the piston 120 until the thrust of the air pressure and the reverse elastic force of the elastic element 130 reach equilibrium and the position of the piston 120 can be stabilized.

[0035] During this process, the rack 124 of the piston 120 drives the rotating shaft 140 to rotate along the second axis A2, causing the pointer 160 to rotate relative to the upper part of the scale 150 until the piston 120 stops, which also stops the rotation of the rotating shaft 140. The pointer 160 then ceases to rotate, and the precise air pressure value is displayed on the scale 150.

[0036] Since the pressure measuring device 100 is removable, the elastic element 130 and the scale 150 are interchangeable. If elastic fatigue occurs after a certain period of use, the elastic element 130 can be replaced to ensure the accuracy of the pressure measuring device 100. The elastic element 130 and the corresponding scale 150 with different coefficients of elasticity can also be replaced simultaneously to change the pressure range that the pressure measuring device can measure.

[0037] Furthermore, the pressure measuring device contains 100, as shown in Fig.Figure 3 shows a housing 170 connected to the cylinder 110 and located between the cylinder 110 and the scale 150. In the present embodiment, the central axis of the housing 170 is orthogonal to the central axis of the cylinder 110. The housing 170 has a through-hole 174 located on the central axis. The through-hole 174 is connected to the interior of the cylinder 110 and corresponds to the central hole 151 of the scale 150. The end 145 of the rotating shaft 140 passes through the through-hole 174 of the housing 170, the central hole 151 of the scale 150, and the hole 161 of the pointer 160.

[0038] The scale 150 is detachably attached to the housing 170. The housing 170 contains a regular polygonal central locking mechanism 172, and the scale contains a regular polygonal central hole 151 that corresponds to the central locking mechanism 172, so that the scale 150 maintains a specific position and orientation relative to the housing 170.

[0039] In the present embodiment, the design in which the scale 150 is separate from the housing 170 allows the scale 150 to be rotated relative to the housing 170 or to be replaced by another scale 150 in order to provide a pressure measuring device 100 with different scale (150) directions or different scales, and can utilize the same production line and the same materials, thereby saving material and simplifying the process.

[0040] Furthermore, in the present embodiment the housing 170 and the cylinder 110 are integrated, which not only simplifies manufacturing and eliminates the need for additional assembly, but also effectively reduces the size.

[0041] Furthermore, the pressure measuring device 100 includes a measuring instrument cover 165 arranged on the housing 170, and the scale 150 and the pointer 160 are located between the housing 170 and the measuring instrument cover 165. The cover 165 is transparent, for example, to make the position of the pointer 160 easily visible and to protect the pointer 160 and the scale 150.

[0042] Based on the foregoing, the piston of the pressure measuring device of the invention includes the rack extending along the first axis. The elastic element is arranged in the cylinder and rests against the second end of the piston. The rotating shaft is rotatably arranged in the cylinder along the second axis, and the ring teeth of the rotating shaft engage with the rack. The scale is located outside the cylinder, and the end of the rotating shaft passes through the center of the scale. The pointer is connected to the end of the rotating shaft and is positioned above the scale. Thus, when gas enters the cylinder from the air inlet, the piston is moved along the first axis, compressing the elastic element. The piston's rack drives the rotating shaft to rotate along the second axis, causing the pointer to rotate relative to the scale to indicate the corresponding air pressure reading. List of reference symbols A1 first axis A2 second axis 100 pressure measuring device 110 cylinders 111 Air connection 112 first through hole 113 second through hole Level 114 115 Opening 116 Interior wall area 117 External threads 120 pistons 121 first end 122 second end 123 platform 124 Rack and pinion 125 Boundary element 126 through groove 130 elastic element 140 Rotary shaft 141 cap 142 first section 143 ring teeth 144 second section 145 End 150 scale 151 Center hole 160 hands 161 holes 162 Peak 165 measuring instrument coverage 170 cases 172 Center lock 174 Through hole 180, 182 sealing ring 185 Coverage 186 internal threads 187 Adjustment hole 190 air nozzle 195 Buckle

Claims

[1] Pressure measuring device (100), comprising: a cylinder (110) comprising an air connection (111); a piston (120) which is movably arranged in the cylinder (110) along a first axis (A1), wherein the piston (120) comprises a first end (121) and a second end (122) which are opposite each other, and a rack (124) which is located between the first end (121) and the second end (122) and extends along the first axis (A1), wherein the first end (121) is located next to the air port (111); an elastic element (130) which is arranged in the cylinder (110) and rests against the second end (122) of the piston (120); a rotary shaft (140) rotatably arranged along a second axis (A2) in the cylinder (110), wherein the rotary shaft (140) comprises ring teeth (143) located in the cylinder (110) and an end (145) projecting from the cylinder (110), the ring teeth (143) engaging with the rack (124); a scale (150) located outside the cylinder (110), wherein the end (145) of the rotating shaft (140) passes through a center point of the scale (150); and a pointer (160) which is connected to the end (145) of the rotating shaft (140) and is located above the scale (150), wherein, when a gas from the air inlet (111) enters the cylinder (110), the piston (120) is pushed to move along the first axis (A1), so that the elastic element (130) is compressed and the rack (124) of the piston (120) drives the rotating shaft (140) to rotate along the second axis (A2), so that the pointer (160) rotates relative to the scale (150) to indicate a corresponding air pressure value. [2] Pressure measuring device (100) according to claim 1, wherein the piston (120) comprises a limiting element (125) located between the first end (121) and the second end (122), the rack (124) faces the limiting element (125) and a through groove (126) is provided between the rack (124) and the limiting element (125), the rotary shaft (140) is arranged in the through groove (126) and the limiting element (125) rests against the rotary shaft (140) so that the ring teeth (143) of the rotary shaft (140) are continuously engaged with the rack (124) during a movement of the piston (120). [3] Pressure measuring device (100) according to claim 2, wherein the cylinder (110) comprises a first through-hole (112) and a second through-hole (113), the rotating shaft (140) comprises a cap (141), a first section (142), the annular teeth (143), a second section (144) and the end (145) arranged in sequence, the cap (141) being located outside the cylinder (110), the size of the cap (141) being larger than the size of the first through-hole (112), the first section (142) being arranged in the first through-hole (112), the limiting element (125) bearing against the first section (142) of the rotating shaft (140), the second section (144) being arranged in the second through-hole (113) and the size of the end (145) being smaller than the size of the second through-hole (113). [4] Pressure measuring device (100) according to any one of claims 1 to 3, wherein the second end (122) of the piston (120) has a shape which is a combination of an arc and a secant, and a platform (123) is provided, the cylinder (110) has a plane which corresponds to the platform (123) therein, so that the piston (120) moves only along the first axis (A1) in the cylinder (110). [5] Pressure measuring device (100) according to any one of claims 1 to 4, further comprising a cover (185), wherein the cover (185) is provided with a triangular adjustment hole (187), wherein the cylinder (110) has an opening (115) located away from the air connection (111), wherein the cover (185) is screwed to the cylinder (110) to close the opening (115), the elastic element (130) rests between the cover (185) and the second end (122) of the piston (120), and the depth of the cover (185) screwed to the cylinder (110) is adjusted to set the degree of compression of the elastic element (130). [6] Pressure measuring device (100) according to any one of claims 1 to 5, further comprising a housing (170) which is connected to the cylinder (110) and is located between the cylinder (110) and the scale (150), wherein the rotating shaft (140) passes through the housing (170) and the scale (150) is detachably arranged on the housing (170). [7] Pressure measuring device (100) according to claim 6, wherein the housing (170) comprises a regular polygonal central locking mechanism (172) and the scale (150) comprises a regular polygonal central hole (151) corresponding to the locking mechanism (172). [8] Pressure measuring device (100) according to claim 6, wherein the housing (170) and the cylinder (110) are integrated. [9] Pressure measuring device (100) according to any one of claims 1 to 8, further comprising a sealing ring (180) adapted to the first end (121) of the piston (120) and bearing against an inner wall surface of the cylinder (110), wherein a cross-section of the sealing ring (180) is circular. [10] Pressure measuring device (100) according to any one of claims 1 to 9, further comprising an air nozzle (190) and a buckle (195), wherein the air nozzle (190) is arranged protruding on the cylinder (110) and is connected to the air connection (111) and the buckle (195) is arranged next to the air nozzle (190) to establish a connection to an air pressure device to be tested.

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