pressure gauge

Abstract

Pressure gauge, comprising a shell (10) comprising a front end plate (11) which is transparent, a rear end plate (12), an inner surface and a ventilation hole (121) formed through the rear end plate (12), a piston base (13) arranged on the inner surface of the rear end plate (12) and having a guide recess (131) formed in a top surface of the piston base (13) and perpendicular to the rear end plate (12), and a position of the guide recess (131) corresponds to a position of the vent hole (121), a scale plate (20) arranged between the front end plate (11) of the shell (10) and the rear end plate (12) of the shell (10), an index pointer (30) arranged on a front surface of the scale plate (20), a piston set (40) arranged in the piston base (13) of the shell (10) and having a plug (41) arranged in the guide recess (131) of the piston base (13), which is movable between the rear end plate (12) of the shell (10) and the scale plate (20) and has a surrounding wall, a front end section, a rear end section and a rack portion (411) formed on the peripheral wall of the plug (41), and teeth of the rack portion (411) are arranged along a movement direction of the plug (41), a piston ring (42) arranged around the plug (41) and disposed between the rear end portion and the rack portion (411) of the plug (41) and adjacent to a wall of the guide recess (131) in an airtight manner, and an elastic element (43) arranged between the plug (41) and the scale plate (20) and having two ends, each adjacent to the plug (41) and the scale plate (20), and a gear transmission set (50) arranged between the rear end plate (12) of the shell (10) and the scale plate (20), connected to the plug (41), arranged through the scale plate (20) and connected to the index pointer (30).

Description

1. Field of the invention

[0001] The invention relates to a pressure gauge and, in particular, to a pressure gauge capable of measuring the pressure of a fluid. 2. Description of the state of the art

[0002] A pressure gauge is usually used to measure the pressure of fluids, such as gas or liquid in closed pipes. Reference is made to Fig. 9. One type of conventional pressure gauge is a Bourdon tube pressure gauge. The Bourdon tube pressure gauge includes an inlet pressure tube 61, a Bourdon tube 62, a transmission mechanism 63, and an index pointer 64. The inlet pressure tube 61 communicates with a closed tube. The Bourdon tube 62 is C-shaped and has an opening end 621 and a closed end 622. The opening end 621 of the Bourdon tube 62 is connected to and communicates with the inlet pressure tube 61. The closed end 622 of the Bourdon tube 62 is connected to the index pointer 64 via the transmission mechanism 63. When the fluid in the closed tube flows into the Bourdon tube 62 via the inlet pressure tube 61, the Bourdon tube 62 would extend outward and deform due to the pressure.This causes the closed end 622 of the Bourdon tube 62 to drive the transmission mechanism 63 to rotate the index pointer 64 and therefore the index pointer can indicate the pressure value in the closed tube.

[0003] The disadvantage of using the Bourdon tube type pressure gauge is that the deformation of the Bourdon tube 62 is unstable at the initial stage of deformation and near the elastic limit. Therefore, if the measured pressure value is smaller than or close to the elastic limit of the Bourdon tube 62, the pressure value may not be accurate.

[0004] Furthermore, document DE 10 2014 216 679 B3 discloses a rapid inflation coupling with a pressure indicator value protection device. Document DE 87 16 171 U1 discloses a clock-like pressure gauge for measuring the pressure inside a tire, and document DE 90 00 876 U1 describes a pressure gauge with a dial in front of which a pointer is positioned to display the measurement results.

[0005] Furthermore, US Patent No. 9,677,965 B2, entitled "PRESSURE GAUGE", discloses a pressure gauge comprising a shell, a shaft, a piston, and a gear. The shaft and the piston are arranged in the shell, and one end of the shaft extends out of the shell. The end of the shaft extending from the shell is connected to the index pointer. The gear is mounted around the shaft. A moving direction of the piston is perpendicular to the shaft. An outer end portion of the piston corresponds to a side opening of a side wall of the shell, and an inner end of the piston is connected to a frame via an extension portion. The frame meshes with the gear. Therefore, when the fluid of the closed pipe pushes the piston from the side opening of the shell, the shaft and the index pointer are driven to rotate by the frame and the gear, thereby indicating the pressure value of the fluid in the closed pipe.

[0006] The problem with the above pressure gauge is that the piston must reconnect to the frame to drive the gear and shaft to rotate. The space occupied by the piston and frame within the casing is large. Due to the space required to operate the frame, the pressure gauge casing is large and cannot be reduced further. Therefore, a pressure gauge that uses a piston and gear to rotate the pointer cannot be used in a small closed circuit.

[0007] The main object of the present invention is to provide a pressure gauge that can measure the pressure of a fluid. The pressure gauge according to the invention comprises a shell, a scale plate, an index pointer, a piston set, and a gear transmission set. The shell has a front end plate, a rear end plate, and a piston base arranged on an inner surface of the rear end plate. The scale plate is arranged between the front end plate of the shell and the rear end plate of the shell. The index pointer is arranged on a front surface of the scale plate. The piston set is arranged in the piston base of the shell. The gear transmission set is arranged between the rear end plate of the shell and the scale plate.

[0008] Other objects, advantages and novel features of the invention will become more apparent from the following detailed description taken in conjunction with the accompanying drawings. DRAWINGS Fig. 1 is a top view of a pressure gauge according to the present invention; Fig. 2 is an exploded perspective view of the pressure gauge in Fig. 1; Fig. 3 is another exploded perspective view of the pressure gauge in Fig. 1; Fig. 4 is another exploded perspective view of the pressure gauge in Fig. 1; Fig. 5 is a perspective view of a piston set and a gear set of the pressure gauge in Fig. 1; Fig. 6 is a side view of the pressure gauge in Fig. 1; Fig. 7 is another top view of the pressure gauge in Fig. 1; Fig. 8 is another top view of the pressure gauge in Fig. 1, shown without an index pointer; and Fig. Figure 9 is a top view of a conventional Bourdon type pressure gauge.

[0009] Reference is made to Fig. 1 and Fig. 2. A pressure gauge according to the present invention comprises a shell 10, a scale plate 20, an index pointer 30, a piston set 40, and a gear set 50.

[0010] Reference is made to Fig. 1, Fig. 2 and Fig. 4. The shell 10 is a cylinder and has a front end plate 11, a rear end plate 12, and a piston base 13. The shell 10 has a front surface and a rear surface. The front end plate 11 is arranged on the front side of the shell 10 and is transparent. The rear end plate 12 is arranged on the rear side of the shell 10. The rear end plate 12 has an inner surface and a vent hole 121. The inner surface of the rear end surface 12 faces an interior of the shell 10. The vent hole 121 is formed through the rear end plate 12. The piston base 13 is arranged on the inner surface of the rear end plate 12 and has a guide recess 131 and a restricting recess 132. The guide recess 131 is formed in a top surface of the piston base 13 and is perpendicular to the rear end plate 12. The position of the guide recess 131 corresponds to the position of the vent hole 121.The guide recess 131 communicates with the ventilation hole 121. The limiting recess 132 is also perpendicular to the rear end plate 12, and the limiting recess 132 communicates with the ventilation hole 121.

[0011] In this embodiment, the shell 10 includes a receiving cylinder 101 and a side cover 102. The receiving cylinder 101 has a first end and a second end. The first end of the receiving cylinder 101 is an opening. The rear end plate 12 is disposed at the second end of the receiving cylinder 101. The front end plate 11 is disposed on the side cover 102. The side cover 102 covers the opening of the receiving cylinder 101 and is disposed on the receiving cylinder 101.

[0012] Reference is made to Fig. 1, Fig. 2, Fig. 4 and Fig. 6. The scale plate 20 is arranged between the front end plate 11 of the shell 10 and the rear end plate 12 of the shell 10. Specifically, the scale plate 20 is arranged between the side cover 102 of the shell 10 and the piston base 13. The scale plate 20 has a front surface 21 and a rear surface 22. The front surface 21 of the scale plate 20 faces the front end plate 11. Scales 23 are formed on the front surface 21 of the scale plate 20, and the scales 23 can display the pressure value. The rear surface 22 of the scale plate 20 faces the rear end plate 12.

[0013] The index pointer 30 is arranged on the front surface 21 of the scale plate 20.

[0014] Reference is made to Fig. 3 and Fig. 5. The piston set 40 is arranged in the piston base 13 of the shell 10 and has a plug 41, a piston ring 42 and an elastic element 43.

[0015] The plug 41 is arranged in the guide recess 131 of the piston base 13. The plug 41 can be moved between the rear end plate 12 of the shell 10 and the scale plate 20. The plug 41 has a peripheral wall, a front end portion, a rear end portion, a rack portion 411, and a positioning block 412. The front end portion of the plug 41 faces the scale plate 20. The rear end portion of the plug 41 faces the rear end plate 12 of the shell 10. The rack portion 411 is formed on the peripheral wall of the plug 41. Teeth of the rack portion 411 are arranged along a moving direction of the plug 41. The positioning block 412 protrudes from the peripheral wall of the plug 41 and the positioning block 412 is inserted into the limiting recess 132 of the piston base 13.Therefore, the plug 41 can only move in a linear direction between the rear end plate 12 of the shell 10 and the scale plate 20.

[0016] The piston ring 42 is arranged around the plug 41 and is interposed between the rear end portion and the rack portion 411 of the plug 41. The piston ring 42 abuts a wall of the guide recess 131 in an airtight manner.

[0017] The elastic member 43 is arranged between the plug 41 and the scale plate 20. The elastic member 43 has two ends, each adjacent to the plug 41 and the scale plate 20. The elastic member 43 would push the plug 41 toward the rear end plate 12 of the shell 10. Specifically, the elastic member 43 is a compression spring. In this embodiment, the plug 41 further has a mounting recess 413 formed in the front end portion. The elastic member 43 is arranged in the mounting recess 413 of the plug 41.

[0018] Reference is made to Fig.5 to 8. The gear transmission set 50 is arranged between the rear end plate 12 of the casing 10 and the scale plate 20. The gear transmission set 50 is connected to the plug 41 and is arranged through the scale plate 20. The gear transmission set 50 is connected to the index pointer 30. The gear transmission set 50 is driven by the plug 41 and drives the index pointer 30 to rotate. Specifically, the gear transmission set 50 includes a first transmission element 51, at least one second transmission element 52, and a transmission gear 53.

[0019] The first transmission member 51 includes a first column 511, an input gear 512, and a drive gear 513. The input gear 512 and the drive gear 513 are formed around the first column 51. The input gear 512 meshes with the rack portion 411 of the plug 41. When the plug 41 moves back and forth in a straight line, the plug 41 can drive the first transmission member 51 to rotate.

[0020] Each of the at least one second transmission element 52 has a second column 521. One of the at least one second transmission element 52 has an output end 5211. The output end 5211 is arranged through the scale plate 20 and is connected to the index pointer 30, causing the index pointer 30 to rotate with respect to the second column 521. In particular, when the at least one second transmission element 52 comprises a plurality of transmission elements 52, the second columns 521 of the plurality of transmission elements 52 are adjacent and parallel to each other. Each second column 521 has a driven gear 522 formed around an outer surface of the second column 521. The driven gears 522 of two adjacent second transmission elements 52 are engaged with each other, causing the second transmission elements 52 to rotate synchronously.

[0021] The transmission gear 53 is formed around the second column 521 of one of the at least one second transmission elements 52. The transmission gear 53 is engaged with the driving gear 513 of the first transmission element 51. Therefore, when the first transmission element 51 is rotated, the first transmission element 51 can drive the at least one second transmission element 52 to rotate, directly or indirectly via the transmission gear 53, and drives the index pointer 30 to rotate.

[0022] In this embodiment, the drive gear 513 of the first transmission element 51 is a straight-cut gear, and the transmission gear 53 is a ring gear. Through the cooperation of the straight-cut gear and the ring gear, the first transmission element 51 can rotate the second transmission element 52. Alternatively, the drive gear 513 of the first transmission element 51 and the transmission gear 53 can be bevel gears.

[0023] In this embodiment, the at least one second transmission element 52 comprises two second transmission elements 52. The two second transmission elements 52 rotate at the same time through the engagement of the two driven gears 522.

[0024] When the pressure gauge according to the present invention is used, the fluid will push the plug 41 over the vent hole 121 of the casing 10, and the plug 41 will drive the index pointer 30 to rotate via the transmission gear set 50. When the fluid pressure value is higher, the pushed distance of the plug 41 is longer and the deflection angle of the index pointer 30 is larger. Therefore, the fluid pressure value can be indicated. After the fluid pressure is released, the elastic member 43 will push the plug 41 to return to its original position.

[0025] The plug 41 will drive the index pointer 30 to rotate backward and return to zero via the transmission gear 50. Since the pressure gauge of the present invention reflects the fluid pressure value according to the linearly compressed distance of the plug 41, it is easy to select the elastic element 43 to have the appropriate elastic coefficient.

[0026] Furthermore, the rack portion 411 of the plug 41 can drive the gear train 50 to operate, so that the piston set 40 and the gear train set 50 can be of compact structure. Therefore, the pressure gauge according to the present invention can be manufactured in a small size and used in a small closed pipe.

Claims

[1] Pressure gauge, comprising a shell (10) comprising a front end plate (11) which is transparent, a rear end plate (12), an inner surface and a ventilation hole (121) formed through the rear end plate (12), a piston base (13) arranged on the inner surface of the rear end plate (12) and having a guide recess (131) formed in a top surface of the piston base (13) and perpendicular to the rear end plate (12), and a position of the guide recess (131) corresponds to a position of the vent hole (121), a scale plate (20) arranged between the front end plate (11) of the shell (10) and the rear end plate (12) of the shell (10), an index pointer (30) arranged on a front surface of the scale plate (20), a piston set (40) arranged in the piston base (13) of the shell (10) and having a plug (41) arranged in the guide recess (131) of the piston base (13), which is movable between the rear end plate (12) of the shell (10) and the scale plate (20) and has a surrounding wall, a front end section, a rear end section and a rack portion (411) formed on the peripheral wall of the plug (41), and teeth of the rack portion (411) are arranged along a movement direction of the plug (41), a piston ring (42) arranged around the plug (41) and disposed between the rear end portion and the rack portion (411) of the plug (41) and adjacent to a wall of the guide recess (131) in an airtight manner, and an elastic element (43) arranged between the plug (41) and the scale plate (20) and having two ends, each adjacent to the plug (41) and the scale plate (20), and a gear transmission set (50) arranged between the rear end plate (12) of the shell (10) and the scale plate (20), connected to the plug (41), arranged through the scale plate (20) and connected to the index pointer (30). [2] Pressure gauge according to claim 1, wherein the gear transmission set (50) comprises a first transmission element (51) comprising a first column (511), an input gear (512) formed around the first column (511) and engaging with the rack portion (411) of the plug (41), and a drive gear (513) formed around the first column (511), at least one second transmission element (52), and each of the second transmission elements (52) has a second column (521), wherein one of the at least one second transmission elements (52) has an output end (5211) arranged through the scale plate (20) and connected to the index pointer (30), and a transmission gear (53) formed around the second column (521) of one of the second transmission elements (52) and meshing with the drive gear (513) of the first transmission element (51). [3] Pressure gauge according to claim 2, wherein the drive gear (513) of the first transmission member (51) is a straight-cut gear and the transmission gear (53) is a ring gear. [4] A pressure gauge according to any one of claims 2 or 3, wherein two second transmission members (52) are provided, the second columns (521) of the two second transmission members (52) being adjacent and parallel to each other, the second column (521) of each second transmission member (52) having a driven gear (522) formed around an outer surface of the second column (521), and the driven gears (522) of the two second transmission members (52) are in mesh with each other. [5] Pressure gauge according to one of claims 1 to 4, wherein the piston base (13) of the casing (10) a limiting recess (132) formed in the piston base (13) which is perpendicular to the rear end plate (12) and communicates with the vent hole (121), and the plug (41) of the piston set (40) a positioning block (412) which protrudes from the surrounding wall of the plug (41) and is inserted into the limiting recess (132). [6] Pressure gauge according to one of claims 1 to 4, wherein the sheath (10) a receiving cylinder (101) which a first end having an opening, and a second end, wherein the rear end plate (12) is arranged at the second end of the receiving cylinder (101), and a side cover (102) covering the opening of the receiving cylinder (101) and arranged on the receiving cylinder (101), wherein the front end plate (11) is arranged on the side cover (102). [7] Pressure gauge according to claim 6, wherein the scale plate (20) is arranged between the side cover (102) of the shell (10) and the piston base (13). [8] A pressure gauge according to any one of claims 1 to 4, wherein the plug (41) further comprises a mounting recess (413) formed in the front end portion of the plug (41), and the elastic member (43) is disposed in the mounting recess (413) of the plug (41).

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