阅读说明：本技术 一种防磨损绝压全自动活塞压力计 (Full-automatic piston pressure gauge of abrasionproof decreases absolute pressure ) 是由 王建武 金勇� 于 2021-09-07 设计创作，主要内容包括：本发明涉及一种防磨损绝压全自动活塞压力计,属于压力计技术领域,包括活塞系统、自挂式砝码自动加载系统和砝码转动机构、真空系统,所述活塞系统包括活塞头和压力控制器,所述自挂式砝码自动加载系统包括支架和自动加载机构,所述的真空系统包括真空罩和真空泵；本发明通过在防磨损绝压全自动活塞压力计内设置自挂式砝码自动加载系统,配合伺服电机驱动大小砝码加载结构进行砝码的自动加载,结构简单,砝码移动控制精度高,操作方便,提高了工作效率,可实现托盘和所有砝码同步转动,可同时进行加减砝码,在加减砝码时基本没有摩擦,通过安装防磨损防断杆的活塞头大大降低了摩擦的可能,显著提高了活塞压力计的稳定性,延长了使用寿命。(The invention relates to an anti-abrasion absolute pressure full-automatic piston pressure gauge, which belongs to the technical field of pressure gauges and comprises a piston system, a self-hanging weight automatic loading system, a weight rotating mechanism and a vacuum system, wherein the piston system comprises a piston head and a pressure controller; according to the invention, the self-hanging type weight automatic loading system is arranged in the anti-abrasion absolute pressure full-automatic piston pressure gauge, the servo motor is matched with the large and small weight loading structures driven by the large and small weight loading systems to automatically load the weights, the structure is simple, the weight movement control precision is high, the operation is convenient, the working efficiency is improved, the tray and all weights can synchronously rotate, the weights can be added and subtracted simultaneously, friction is basically avoided during weight addition and subtraction, the possibility of friction is greatly reduced by installing the piston head of the anti-abrasion and anti-breakage rod, the stability of the piston pressure gauge is obviously improved, and the service life is prolonged.)

1. The utility model provides a full-automatic piston pressure gauge of abrasionproof decreases absolute pressure which characterized in that: the automatic loading device comprises a piston system, a self-hanging weight automatic loading system, a weight rotating mechanism and a vacuum system;

the piston system is connected with the self-hanging weight automatic loading system;

the weight rotating mechanism is arranged on the self-hanging weight automatic loading system;

the piston system, the self-hanging weight automatic loading system and the weight rotating mechanism are arranged in the vacuum system.

2. The fully automatic piston pressure gauge of claim 1, further comprising:

the self-hanging type weight automatic loading system comprises a large weight loading system and a small weight loading system, wherein the large weight loading system and the small weight loading system are both arranged on a frame, and the frame comprises an upper top plate (23), a lower bottom plate (24) and a guide rail supporting rod (39);

the large weight loading system comprises a large weight supporting plate (10), a screw rod (9), a first screw rod nut (36), a first motor (7) and a support, wherein the large weight supporting plate (10) is placed at the top of the first screw rod nut (36), the first screw rod nut (36) is in threaded connection with the screw rod (9), and the first motor (7) is installed on the large weight supporting plate (10);

the support comprises a large weight hanging block (1), an upper support (2) and a lower support (3), the lower support (3) is connected with a support plate (10) through a first bearing (33), a first motor (7) drives a first synchronous wheel (8) to rotate through a synchronous wheel and a synchronous belt, the first synchronous wheel (8) is fixedly connected with a first lead screw nut (36), the first synchronous wheel and the first lead screw nut are integrally formed, the first synchronous wheel (8) drives the first lead screw nut (36) to rotate, so that the support plate (10) moves up and down, when the support plate (10) moves up, a large weight (27) is hung on the support, and when the support plate (10) moves down, the large weight (27) is loaded on a weight hanging disc tray (26);

the piston system comprises a piston head (30) arranged in the self-hanging weight automatic loading system and a piston pressure controller (32) connected with the piston head; the piston head (30) is arranged on a piston head mounting base (40) in the tray driving synchronizing wheel (21), the synchronizing wheel mounting cylinder (22), the transition block (34), the driving cylinder (35), the second bearing (14) and the small weight tray (15), and the piston pressure controller (32) is connected with the piston head (30) through the piston head mounting base (40);

the small weight loading system comprises a small weight supporting plate (13), a small weight tray (15), a screw rod (9), a second screw rod nut (37), a second motor (11) and a second synchronizing wheel (12), wherein the small weight supporting plate (13) is placed on the second screw rod nut (37), the small weight tray (15) is placed on the small weight supporting plate (13), the second screw rod nut (37) is in threaded connection with the screw rod (9), and the second motor (11) is installed on the small weight supporting plate (13); the second motor (11) drives the second synchronizing wheel (12) to rotate through the synchronizing wheel and the synchronous belt, the second synchronizing wheel (12) is fixedly connected with the second lead screw nut (37), the second synchronizing wheel and the second lead screw nut are integrally formed, the second synchronizing wheel (12) drives the second lead screw nut (37) to rotate, the supporting plate (13) is made to move up and down, the small weights (28) are loaded on the small weight tray (15) when the supporting plate (13) moves up, and the small weights (28) are hung on the small weight tray (15) when the supporting plate (13) moves down; a weight hanging tray (26) is arranged on the piston head (30), large and small weights can be loaded on the weight hanging tray (26), and the distance of the weight hanging tray (26) moving up and down is measured by a position sensor (29);

the large weight support plate (10) and the small weight support plate (13) are connected with the guide rail support rod (39) through bearings.

3. The fully automatic piston pressure gauge of claim 2, wherein:

the weight rotating mechanism comprises a driving rod system, a large weight rotating mechanism and a tray small weight rotating mechanism;

the driving rod system comprises a third motor (16), a speed change system (17) and a driving rod (18), wherein the third motor (16) drives the driving rod (18) to rotate through the speed change system (17);

the large weight rotating mechanism comprises a support and a synchronizing wheel system, the support comprises a large weight hanging block (1), an upper support (2) and a lower support (3), a first bearing (33) and a fourth synchronizing wheel (6) are mounted on the lower support (3), the lower support (3) is connected with a support plate (10) through the first bearing (33), a driving rod (18) drives the fourth synchronizing wheel (6) to rotate through a third synchronizing wheel (4) and a first synchronizing belt (5), and the fourth synchronizing wheel (6) drives a large weight (27) to rotate in the horizontal direction through the lower support (3), the upper support (2) and the large weight hanging block (1);

the tray small weight rotating mechanism comprises a fifth synchronizing wheel (19), a second synchronizing belt (20), a tray driving synchronizing wheel (21), a synchronizing wheel mounting cylinder (22), a transition block (34), a driving cylinder (35), a second bearing (14) and a small weight tray (15), wherein the driving rod (18) drives the tray driving synchronizing wheel (21) to rotate through the fifth synchronizing wheel (19) and the second synchronizing belt (20), the tray driving synchronizing wheel (21) drives the small weight tray (15) to rotate through the synchronizing wheel mounting cylinder (22), the transition block (34) and the driving cylinder (35), and the small weight tray (15) drives the small weight to rotate; the driving cylinder (35) drives the weight hanging tray (26) to rotate, and the weight hanging tray (26) drives the large weight (27) and the small weight (28) loaded on the tray (15) to synchronously rotate.

4. The fully automatic piston pressure gauge of claim 3, wherein:

the vacuum system comprises a vacuum cover (25), a vacuum pump (31) and a vacuum sensor (38), the vacuum cover (25) covers the bottom plate of the weight loading system, the weight rotating system and the piston system, the vacuum pump (31) is connected with the inner cavity of the vacuum cover (25), and the vacuum sensor (38) is arranged in the inner cavity of the vacuum cover (25); and starting the vacuum pump (31) when the measurement is started, vacuumizing the space in the vacuum cover (25), reading absolute pressure when the vacuum degree reaches within 50Pa, and compensating the absolute pressure reading by the vacuum degree.

Technical Field

The invention relates to the technical field of piston type pressure gauges, in particular to an anti-abrasion absolute pressure full-automatic piston type pressure gauge.

Background

A piston manometer is a gauge that measures pressure using the principle of hydrostatic balance (i.e., the fluid pressure acting on the active area of the piston is balanced by the weight it is loaded with). The absolute pressure piston manometer generally comprises a piston system, a special weight, a pressure controller and a vacuum system. Most piston manometers are manually added with weights, are manually pressurized, and waste time and labor in verification work. When the manual absolute pressure piston pressure gauge works, a vacuum cover must be opened at first, weights are placed manually, the vacuum cover is covered, vacuumizing is performed, pressure is controlled, the piston is in a suspension state, a power supply of a rotating motor is turned on, the weights are rotated, reading is performed, in the vacuumizing process, the pressure is adjusted at any time in a manual mode, the piston is kept in the suspension state, the operation is troublesome and difficult, if the piston does not stop rotating at any moment in the suspension state, each detection point must be repeated, the vacuumizing time is long, the detection time is long, and the working efficiency is extremely low. If the pressure control is not good, the piston system is in the limit position and does not stop rotating immediately, abrasion is generated, and the fact that the piston system stops rotating immediately when in the limit position is difficult to guarantee, so that the abrasion is generated frequently.

The existing automatic weight adding piston pressure gauges are like common pistons, weights added on a hanging basket or a tray rotate, weights not placed on the hanging basket or the tray are hung by a static lifting hook and do not rotate, when the weights are added or reduced, friction can be generated between the weights, and the measuring error is possible to exceed the standard for a precision piston system with the accuracy of 0.005% and the like due to the slight change of the weight mass; some automatic weight pistons that add stop rotating earlier the weight that adds on string blue or tray when adding the plus-minus weight, subtract the weight again, then rotate string blue or tray again, troublesome operation like this, speed is slow, and work efficiency is low, and the work efficiency that often is full-automatic piston does not have ordinary manual piston height yet.

Accordingly, there is a need for improvements in the art.

Disclosure of Invention

The invention aims to provide an efficient anti-abrasion absolute pressure full-automatic piston pressure gauge.

In order to solve the technical problem, the invention provides an anti-abrasion absolute pressure full-automatic piston pressure gauge which comprises a piston system, a self-hanging weight automatic loading system, a weight rotating mechanism and a vacuum system, wherein the piston system is connected with the self-hanging weight automatic loading system;

the piston system is connected with the self-hanging weight automatic loading system;

the weight rotating mechanism is arranged on the self-hanging weight automatic loading system;

the piston system, the self-hanging weight automatic loading system and the weight rotating mechanism are arranged in the vacuum system;

the self-hanging weight automatic loading system comprises a large weight loading system and a small weight loading system.

As a further technical scheme of the invention:

the large weight loading system and the small weight loading system are both arranged on the frame, and the frame comprises an upper top plate, a lower bottom plate and a guide rail supporting rod;

the large weight loading system comprises a large weight supporting plate, a screw rod, a first screw nut, a first motor and a bracket, wherein the large weight supporting plate is placed at the top of the first screw nut;

the support comprises a large weight hanging block, an upper support and a lower support, the lower support is connected with a support plate through a first bearing, a first motor drives a first synchronizing wheel to rotate through a synchronizing wheel and a synchronizing belt, the first synchronizing wheel is fixedly connected with a first lead screw nut, the first synchronizing wheel and the first lead screw nut are integrally formed, the first synchronizing wheel drives the first lead screw nut to rotate, the support plate is enabled to move up and down, the large weight is hung on the support when the support plate moves upwards, and the large weight is loaded on a weight hanging tray when the support plate moves downwards;

the piston system comprises a piston head arranged in the self-hanging weight automatic loading system and a piston pressure controller connected with the piston head; the piston head is arranged on a piston head mounting base in the tray driving synchronizing wheel, the synchronizing wheel mounting cylinder, the transition block, the driving cylinder, the second bearing and the small weight tray, and the piston pressure controller is connected with the piston head through the piston head mounting base;

the small weight loading system comprises a small weight supporting plate, a small weight tray, a screw rod, a second screw nut, a second motor and a second synchronous wheel, wherein the small weight supporting plate is placed on the second screw nut; the second motor drives a second synchronizing wheel to rotate through a synchronizing wheel and a synchronizing belt, the second synchronizing wheel is fixedly connected with a second screw nut and integrally formed, the second synchronizing wheel drives the second screw nut to rotate, so that the supporting plate moves up and down, small weights are loaded on the small weight tray when the supporting plate moves upwards, and the small weights are hung on the small weight tray when the supporting plate moves downwards; a weight hanging tray is arranged on the piston head, large and small weights can be loaded on the weight hanging tray, and the distance of the weight hanging tray moving up and down is measured by a position sensor;

the large weight supporting plate and the small weight supporting plate are connected with the guide rail supporting rod through bearings.

As a further technical scheme of the invention:

the weight rotating mechanism comprises a driving rod system, a large weight rotating mechanism and a tray small weight rotating mechanism;

the driving rod system comprises a third motor, a speed change system and a driving rod, and the third motor drives the driving rod to rotate through the speed change system;

the large weight rotating mechanism comprises a support and a synchronizing wheel system, the support comprises a large weight hanging block, an upper support and a lower support, a first bearing and a fourth synchronizing wheel are mounted on the lower support, the lower support is connected with a support plate through the first bearing, a driving rod drives the fourth synchronizing wheel to rotate through a third synchronizing wheel and a first synchronizing belt, and the fourth synchronizing wheel drives the large weight to rotate in the horizontal direction through the lower support, the upper support and the large weight hanging block;

the tray small weight rotating mechanism comprises a fifth synchronizing wheel, a second synchronizing belt, a tray driving synchronizing wheel, a synchronizing wheel mounting cylinder, a transition block, a driving cylinder, a second bearing and a small weight tray, a driving rod drives the tray driving synchronizing wheel to rotate through the fifth synchronizing wheel and the second synchronizing belt, the tray driving synchronizing wheel drives the small weight tray to rotate through the synchronizing wheel mounting cylinder, the transition block and the driving cylinder, and the small weight tray drives the small weight to rotate; the driving barrel drives the weight hanging tray to rotate, and the weight hanging tray drives the large weights and the small weights loaded on the tray to synchronously rotate.

As a further technical scheme of the invention:

the vacuum system comprises a vacuum cover, a vacuum pump and a vacuum sensor, the vacuum cover covers the bottom plate so as to cover all the piston systems, the weight loading system and the weight rotating system, the vacuum pump is connected with the inner cavity of the vacuum cover, and the vacuum sensor is arranged in the inner cavity of the vacuum cover; and starting a vacuum pump when measurement is started, vacuumizing the space in the vacuum cover, reading absolute pressure when the vacuum degree reaches within 50Pa, and compensating the absolute pressure reading by the vacuum degree.

The technical advantages of the anti-abrasion absolute pressure full-automatic piston pressure gauge provided by the invention are as follows:

according to the anti-abrasion absolute pressure full-automatic piston pressure gauge, the self-hanging type automatic weight loading system is arranged in the vacuum cover of the anti-abrasion absolute pressure full-automatic piston pressure gauge, the servo motor is matched to drive the large and small weight loading mechanisms to automatically load weights, the vacuum cover does not need to be opened in the verification process, the piston pressure gauge is always in a vacuum state, the structure is simple, the weight movement control precision is high, the operation is convenient, the working efficiency is improved, the weights loaded on the tray and not loaded on the tray can synchronously rotate, the weights can be added and subtracted simultaneously, basically no friction exists when the weights are added and subtracted, the possibility of friction is greatly reduced by installing the piston head of the anti-abrasion anti-breakage rod, the stability of the piston pressure gauge is obviously improved, and the service life is prolonged.

Drawings

The following describes embodiments of the present invention in further detail with reference to the accompanying drawings.

FIG. 1 is a schematic structural view showing that the weights of the abrasion-proof absolute pressure full-automatic piston pressure gauge are hung up completely;

FIG. 2 is a schematic structural diagram of the abrasion-proof absolute pressure fully automatic piston pressure gauge of the present invention, which is fully loaded on a tray;

fig. 3 is a schematic structural view of the large weight 27 and the small weight 28.

In the figure: 1-large weight hanging block, 2-upper bracket, 3-lower bracket, 4-third synchronizing wheel, 5-first synchronizing belt, 6-fourth synchronizing wheel, 7-first motor, 8-first synchronizing wheel, 9-screw rod, 10-large weight supporting plate, 11-second motor, 12-second synchronizing wheel, 13-small weight supporting plate, 14-second bearing, 15-small weight tray, 16-third motor, 17-speed change system, 18-driving rod, 19-fifth synchronizing wheel, 20-second synchronizing belt, 21-tray driving synchronizing wheel, 22-synchronizing wheel mounting cylinder, 23-upper top plate, 24-lower base plate, 25-vacuum cover, 26-weight hanging disc, 27-large weight, 28-small weight, 21-tray driving synchronizing wheel, 29-displacement sensor, 30-piston head, 31-vacuum pump, 32-pressure controller, 33-first bearing, 34-transition block, 35-driving cylinder, 36-first screw nut, 37-second screw nut, 38-vacuum sensor, 39-guide rail support rod, 40-piston head mounting base.

Detailed Description

The invention will be further described with reference to specific examples, but the scope of the invention is not limited thereto.

Embodiment 1, an anti-abrasion absolute pressure full-automatic piston manometer, as shown in fig. 1-3, comprises a piston system, a self-hanging weight automatic loading system, a weight rotating mechanism, and a vacuum system,

the piston system comprises a piston head 30 arranged in the self-hanging weight automatic loading system and a piston pressure controller 32 connected with the piston head 30, wherein the piston head 30 comprises a piston rod and a piston cylinder limiting seat, and in the automatic weight adding and pressurizing process, weight adding and pressurizing cannot be completely synchronous, so that the piston rod can work at the upper and lower limit positions, and in order to prevent abrasion when the piston rod works at the upper and lower limit positions, the piston head 30 of an abrasion and breakage preventing rod is adopted, and the possibility of abrasion is further reduced;

as a further technical scheme of the patent: the self-hanging weight automatic loading system comprises a large weight loading system and a small weight loading system, wherein the large weight loading system and the small weight loading system are both arranged on a frame, and the frame consists of an upper top plate 23, a lower bottom plate 24 and a guide rail supporting rod 39;

the large weight loading system comprises a large weight supporting plate 10, a screw rod 9, a first screw nut 36, a first motor 7 and a support, wherein the large weight supporting plate 10 is placed at the top of the first screw nut 36, the first screw nut 36 is in threaded connection with the screw rod 9, and the first motor 7 is installed on the large weight supporting plate 10.

The support comprises a large weight hanging block 1, an upper support 2 and a lower support 3, the lower support 3 is connected with a support plate 10 through a first bearing 33, and a first motor 7 drives a first synchronous wheel 8 to rotate through a synchronous wheel and a synchronous belt; the first synchronizing wheel 8 and the first screw nut 36 are fixedly connected through a screw nut and a key on the connecting block, the first synchronizing wheel 8 drives the first screw nut 36 to rotate, so that the supporting plate 10 moves up and down, the large weight 27 is hung on the bracket when the supporting plate 10 moves up, and the large weight 27 is loaded on the weight hanging disc 26 when the supporting plate 10 moves down;

the small weight loading system comprises a small weight supporting plate 13, a small weight tray 15, a screw rod 9, a second screw nut 37, a second motor 11 and a second synchronizing wheel 12, wherein the small weight supporting plate 13 is placed on the second screw nut 37, the small weight tray 15 is placed on the small weight supporting plate 13, the second screw nut 37 is in threaded connection with the screw rod 9, and the second motor 11 is installed on the small weight supporting plate 13; the second motor 11 drives the second synchronizing wheel 12 to rotate through the synchronizing wheel and the synchronizing belt, the second synchronizing wheel 12 is fixedly connected with the second lead screw nut 37, the second synchronizing wheel 12 and the second lead screw nut 37 are integrated, the second synchronizing wheel 12 drives the second lead screw nut 37 to rotate, the support plate 13 is enabled to move up and down, the small weights 28 are loaded on the small weight tray 15 when the support plate 13 moves upwards, and the small weights 28 are hung on the small weight tray 15 when the support plate 13 moves downwards; the piston head 30 is provided with a weight hanging disc 26, large and small weights can be loaded on the weight hanging disc 26, and the up-and-down movement distance of the weight hanging disc 26 is measured by a position sensor 29.

The piston system comprises a piston head 30 arranged in the self-hanging weight automatic loading system and a piston pressure controller 32 connected with the piston head 30, the piston head 30 is arranged on a piston head mounting base 40 in the tray driving synchronizing wheel 21, the synchronizing wheel mounting cylinder 22, the transition block 34, the driving cylinder 35, the second bearing 14 and the small weight tray 15, and the piston pressure controller 32 is connected with the piston head 30 through the piston head mounting base 40.

The large weight 27 and the small weight 28 have the same structure and are both: from the top down including last weight main part ring 271 and weight main part ring 272 down, the diameter of going up weight main part ring 271 is less than the diameter of weight main part ring 272 down, it is provided with the level outside last baffle 273 that extends to go up weight main part ring 271 top lateral wall, weight main part ring 272 bottom inside wall is provided with level inside extension down baffle 274 down, the last weight main part ring 271 of a big weight 27 (or little weight 28) stretches into in the inner chamber of the lower weight main part ring 272 of another big weight 27 (or little weight 28), the external diameter of going up baffle 273 is greater than the internal diameter of baffle 274 down, connect adjacent big weight 27 (or little weight 28) through going up baffle 273 and baffle 274 down.

When the weights (the large weight 27 and the small weight 28) are lifted up, the characteristic parameter d must be the same as the characteristic parameter d when the weights are put down, d is the step length of moving the weights up and down, if n weights are to be put down, the weight hanging block moves down by the distance of n x d, and the n weights are placed on the tray, and similarly, if the n weights are to be lifted up, the weight hanging block moves up by the distance of n x d, and the n weights leave the tray, further, the characteristic parameter d is set to be more suitable as the piston stroke plus 4mm, the piston stroke is generally 3-4mm, and the lifted weight cannot collide or rub with the put-down weight when the piston is jacked up or sunk.

The large weight support plate 10 and the small weight support plate 13 are connected with the guide rail support rod 39 through bearings;

as a further technical scheme of the patent: the weight rotating mechanism comprises a driving rod system, a large weight rotating mechanism and a tray small weight rotating mechanism;

the driving rod system comprises a third motor 16, a speed change system 17 and a driving rod 18, wherein the third motor 16 drives the driving rod 18 to rotate through the speed change system 17;

the large weight rotating mechanism comprises a support and a synchronous wheel system, the support comprises a large weight hanging block 1, an upper support 2 and a lower support 3 (namely the support of the large weight loading system), a first bearing 33 and a fourth synchronous wheel 6 are installed on the lower support 3, the lower support 3 is fixedly connected with a support plate 10 through the first bearing 33, a driving rod 18 drives the fourth synchronous wheel 6 to rotate through a third synchronous wheel 4 and a first synchronous belt 5, and the fourth synchronous wheel 6 drives a large weight 27 to rotate in the horizontal direction through the lower support 3, the upper support 2 and the large weight hanging block 1;

the tray small weight rotating mechanism comprises a fifth synchronizing wheel 19, a second synchronizing belt 20, a tray driving synchronizing wheel 21, a synchronizing wheel mounting cylinder 22, a transition block 34, a driving cylinder 35, a second bearing 14 and a small weight tray 15, and the driving rod 18 drives the tray driving synchronizing wheel 21 to rotate through the fifth synchronizing wheel 19 and the second synchronizing belt 20; tray drive synchronizing wheel 21, synchronizing wheel installation section of thick bamboo 22, transition piece 34, drive cylinder 35 pass through screw thread fixed connection, and drive cylinder 35 and little weight tray 15 pass through the spout to be connected, and little weight tray 15 can reciprocate outside drive cylinder 35. The tray driving synchronizing wheel 21 drives the small weight tray 15 to rotate through the synchronizing wheel mounting cylinder 22, the transition block 34 and the driving cylinder 35, and the small weight tray 15 drives the small weight to rotate; the driving cylinder 35 drives the weight hanging disc 26 to rotate, and the weight hanging disc 26 drives the large weight 27 and the small weight 28 loaded on the weight hanging disc 26 to synchronously rotate. Thus, the large weight 27 hung on the stand, the small weight 28 placed on the small weight tray, and the weight hanging tray 26 rotate in synchronization. The rotating speed ratio of the large weight rotating driving wheel 6 to the tray small weight rotating driving wheel 35 is the same, namely the rotating speeds of the two driving wheels are the same, so that the weights basically have no friction in the addition and subtraction processes, and the precision of the piston pressure gauge is improved.

As a further technical scheme of the patent: the vacuum system comprises a vacuum cover 25, a vacuum pump 31 and a vacuum sensor 38, wherein the vacuum cover 25 covers the bottom plate 24, so that all the piston systems, the weight loading system and the weight rotating system are covered (the third motor 16 is rotated and placed in a normal pressure state, and heat dissipation is facilitated), the vacuum pump 31 is connected with the inner cavity of the vacuum cover 25, and the vacuum sensor 38 is arranged in the inner cavity of the vacuum cover 25; and starting the vacuum pump 31 when measurement is started, vacuumizing the space in the vacuum cover 25, reading absolute pressure when the vacuum degree reaches within 50Pa, and compensating the absolute pressure reading by the vacuum degree.

Finally, it is also noted that the above-mentioned lists merely illustrate a few specific embodiments of the invention. It is obvious that the invention is not limited to the above embodiments, but that many variations are possible. All modifications which can be derived or suggested by a person skilled in the art from the disclosure of the present invention are to be considered within the scope of the invention.