1. A reaction-sensitive pressure sensor for a vehicle, comprising a housing (1), characterized in that: the bottom end of the shell (1) is fixedly provided with a connector (2), the outer side of the connector (2) is provided with a threaded connector, the bottom end of the connector (2) is provided with an air inlet (3), the interior of the air inlet (3) is provided with a cavity (4), the interior of the cavity (4) is provided with a first movable plug (5), the top end of the first movable plug (5) is fixedly provided with a first piston rod (6), the outer side of the first piston rod (6) is sleeved with a first spring (7), the top end of the first piston rod (6) is fixedly provided with a first piston plate (8), the top of the first piston plate (8) is provided with a compression cavity (9), one side of the top of the compression cavity (9) is provided with a communication port (10), the communication port (10) is fixedly connected with a second compression cavity (11), the top of the second compression cavity (11) is provided with an oil cavity (12), and the oil cavity (12) is fixedly connected with a cooling cavity (13), the cooling device is characterized in that a second movable plug (14) is arranged in the cooling cavity (13), a cleaning disc (15) is arranged at the top of the cooling cavity, a rotating disc (16) is fixedly connected to the top end of the cleaning disc (15), and a potentiometer (17) is arranged on one side of the rotating disc (16).

2. A responsive pressure sensor for an automobile as claimed in claim 1, wherein: be provided with fixed plate (18) between first activity stopper (5) and first piston board (8), first piston rod (6) are provided with two sets ofly, and are two sets of first piston rod (6) are installed in first activity stopper (5) top both sides along cavity (4) central point symmetry respectively, first piston rod (6) all run through fixed plate (18) top one side and are connected to first piston board (8), first piston rod (6) all with fixed plate (18) swing joint, first piston rod (6) are close to fixed plate (18) bottom one side and all overlap and have first spring (7).

3. A responsive pressure sensor for an automobile as claimed in claim 1, wherein: one side is provided with piston head (19) in compression chamber (9), piston head (19) are including chassis (20), activity post (21) and separation blade (22), intercommunication mouth (10) top one side sets up by draw-in groove (23), draw-in groove (23) are provided with two sets ofly, and are two sets of compression chamber (9) central axis symmetry is followed respectively in draw-in groove (23), and are two sets of all be provided with spring strip (24) in draw-in groove (23), equal fixedly connected with activity post (21) in spring strip (24) bottom, activity post (21) are close to compression chamber (9) one side fixed mounting and have separation blade (22), activity post (21) run through intercommunication mouth (10) one side fixedly connected with chassis (20), activity post (21) bottom cover has second spring strip (25), just activity post (21) both ends diameter all is greater than the intermediate position diameter.

4. A responsive pressure sensor for an automobile as claimed in claim 1, wherein: the second compression cavity (11) and the oil cavity (12) are arranged in two groups, the second compression cavity (11) and the oil cavity (12) are symmetrically arranged on two sides of the outer wall of the cooling cavity (13) along the central line of the cooling cavity (13), a third movable plug (26) is arranged between the second compression cavity (11) and the oil cavity (12), the top end of the third movable plug (26) is fixedly connected with a third movable column (27), a third piston plate (28) is fixedly arranged at the top end of the third movable column (27), an oil cavity (12) is arranged at the top of the third piston plate (28), a cooling pipeline (29) is fixedly connected with one side of the oil cavity (12), the other end of the cooling pipeline (29) is fixedly connected with a cooling cavity (13), the oil cavity (12) and the cooling cavity (13) are communicated with each other through the cooling pipeline (29), and cooling oil (30) is arranged in the oil cavity (12) and the cooling cavity (13).

5. A responsive pressure sensor for an automobile as claimed in claim 1, wherein: the utility model discloses a cooling chamber (13) internal fixed mounting has second fixed plate (31), second fixed plate (31) bottom one side is provided with second movable stopper (14), the equal fixed mounting in second movable stopper (14) top both sides has second piston rod (32), second piston rod (32) run through second fixed plate (31) fixedly connected with second piston board (33), swing joint between second piston rod (32) and second fixed plate (31), second piston rod (32) one side is located and all overlaps between second piston board (33) and second fixed plate (31) has second spring (34).

6. A responsive pressure sensor for a vehicle as claimed in claim 1 or 5, wherein: second piston plate (33) top is provided with clearance dish (15), clearance dish (15) bottom fixedly connected with dwang (35), dwang (35) run through second piston plate (33) top one side, are provided with movable block (41) in carrying second piston plate (33), dwang (35) all are provided with helicitic texture with movable block (41) contact site, clearance dish (15) outside sets up and uses the scraper blade, clearance dish (15) bottom is provided with the separation net.

7. A responsive pressure sensor as claimed in claim 1 or 6, said potentiometer (17) comprising a sliding post (39) and a stop bar (40), a connecting column (36) is fixedly arranged at the center of the top end of the cleaning disc (15), the top end of the connecting column (36) is fixedly connected with a fixing frame (37), a rotating disc (16) is fixedly arranged at the top end of the fixed frame (37), a spiral groove (38) is arranged at one side of the top end of the rotating disc (16), a sliding column (39) is arranged in the spiral groove (38), a resistance strip (40) is arranged at one side of the sliding column (39), two groups of the blocking strips (40) are arranged, one end of each group of the blocking strips (40) penetrates through one side of the sliding column (39), the other end of the resistance strip (40) penetrates through one side of the inner wall of the shell to be connected to the chip, and the resistance strip (40) is connected with the sliding column (39) in a sliding mode.

Background

The automobile air inlet pressure sensor is mounted on the manifold of the back door of the automobile throttle valve, detects the absolute pressure of the air inlet manifold behind the throttle valve, detects the change of the absolute pressure in the manifold according to the rotating speed and the load of the engine, converts the absolute pressure into signal voltage and sends the signal voltage to the electronic controller, and the electronic controller controls the basic oil injection quantity according to the signal voltage. Traditional car air intake pressure sensor inserts back in the air intake manifold, thereby air pressure in the air intake manifold will direct effect on the pressure chip, form the signal of telecommunication, conduct electronic controller on the car, perhaps make the ripple diaphragm produce the displacement through air pressure, and then make the contact on the potentiometre slide, thereby change the resistance value, change the size of electric current, measure the size of air intake pressure, but two kinds of measuring methods connect and have some not enoughly, gas pressure can produce a large amount of heat energy when conducting to pressure sensor in, influence the measuring result and make resistance displacement with the tympanic membrane situation through the diaphragm simultaneously, it has the location inaccurate, the reaction is sensitive inadequately, can't the accuracy measure, lead to measuring inaccurate.

Disclosure of Invention

The invention aims to provide a pressure sensor for an automobile with sensitive reaction, which has the advantages of accurate positioning, sensitive reaction and capability of carrying out accurate measurement and solves the problems in the background technology.

In order to achieve the purpose, the invention provides the following technical scheme: a pressure sensor sensitive in reaction for an automobile comprises a shell, wherein a connector is fixed at the bottom end of the shell, a threaded connector is arranged on the outer side of the connector, an air inlet is formed in the bottom end of the connector, a cavity is formed in the air inlet, a first movable plug is arranged in the cavity, a first piston rod is fixedly mounted at the top end of the first movable plug, a first spring is sleeved on the outer side of the first piston rod, a first piston plate is fixedly mounted at the top end of the first piston rod, a compression cavity is formed in the top of the first piston plate, a communicating port is formed in one side of the top of the compression cavity, a second compression cavity is fixedly connected with the communicating port, an oil cavity is formed in the top of the second compression cavity, the oil cavity is fixedly connected with a cooling cavity, a second movable plug is arranged in the cooling cavity, a cleaning disc is arranged at the top of the cleaning disc, and a rotating disc is fixedly connected with the top end of the cleaning disc, and a potentiometer is arranged on one side of the rotating disc.

Preferably, be provided with the fixed plate between first activity stopper and the first piston board, first piston rod is provided with two sets ofly, two sets of first piston rod is installed in first activity stopper top both sides along cavity central point respectively to put the symmetry, first piston rod all runs through fixed plate top one side and is connected to first piston board, first piston rod all with fixed plate swing joint, first piston rod all overlaps on one side near the fixed plate bottom and has first spring.

Preferably, one side is provided with the piston head in the compression chamber, the piston head includes chassis, activity post and separation blade, intercommunication mouth top one side sets up by the draw-in groove, the draw-in groove is provided with two sets ofly, and is two sets of compression chamber central axis symmetry is followed respectively to the draw-in groove all be provided with the spring strip in the draw-in groove, the equal fixedly connected with activity post in spring strip bottom, the activity post is close to compression chamber one side fixed mounting and has the separation blade, the activity post runs through intercommunication mouth one side fixedly connected with chassis, activity post bottom cover has the second spring strip, just activity post both ends diameter all is greater than the intermediate position diameter.

Preferably, the second compression chamber and the oil cavity are both arranged by two sets, the second compression chamber and the oil cavity are both symmetrically arranged on two sides of the outer wall of the cooling cavity along the central line of the cooling cavity, a third movable plug is arranged between the second compression chamber and the oil cavity, a third movable plug top end fixedly connected with a third movable column is arranged on the top end of the third movable column, a third piston plate is fixedly arranged on the top end of the third piston plate, the oil cavity is arranged on the top of the third piston plate, a cooling pipeline is fixedly connected to one side of the oil cavity, a cooling cavity is fixedly connected to the other end of the cooling pipeline, the oil cavity and the cooling cavity are communicated with each other through the cooling pipeline, and cooling oil is arranged in the oil cavity and the cooling cavity.

Preferably, the cooling cavity is internally and fixedly provided with a second fixed plate, one side of the bottom of the second fixed plate is provided with a second movable plug, two sides of the top end of the second movable plug are fixedly provided with a second piston rod, the second piston rod penetrates through a second fixed plate fixedly connected with a second piston plate, the second piston rod is movably connected with the second fixed plate, and one side of the second piston rod is positioned between the second piston plate and the second fixed plate and is sleeved with a second spring.

Preferably, second piston plate top is provided with the clearance dish, clearance dish bottom fixedly connected with dwang, the dwang runs through second piston plate top one side, be provided with the movable block in the second piston plate, dwang and movable block contact site all are provided with helicitic texture, the clearance dish outside sets up with the scraper blade, clearance dish bottom is provided with the separation net.

Preferably, the potentiometre is including the slip post and hinder the strip, clearance dish top central point puts fixed mounting with the spliced pole, spliced pole top fixedly connected with mount, mount top fixed mounting has the rotary disk, rotary disk top one side is provided with the helicla flute, be provided with the slip post in the helicla flute, slip post one side is provided with hinders the strip, it is provided with two sets ofly, two sets of to hinder strip one end and all run through slip post one side, hinder the strip other end and all run through shells inner wall one side and be connected to the chip, just hinder equal sliding connection between strip and the slip post.

Compared with the prior art, the invention has the following beneficial effects:

1. the pressure sensor for the automobile with sensitive reaction is provided with the first movable plug, and the first movable plug is pushed to move and the first piston plate moves upwards by the gas entering the cavity, the compression cavity is compressed, the chassis and the movable column move upwards at the same time, the communication port and the compression cavity can be communicated with each other through the upward movement of the chassis and the movable column, the communicating opening is communicated with the compression cavity, so that the compression cavity can apply air pressure to the second compression cavity through the communicating opening, meanwhile, the air pressure in the second compression cavity generates an upward driving force on the third movable plug and the third piston plate, the cooling oil in the oil cavity is conveyed into the cooling cavity through the cooling pipeline, the cooling cavity is cooled along with the cooling oil, so that the problem that a large amount of heat energy is generated when the gas pressure is conducted into the pressure sensor can be effectively solved, and the accuracy of a measuring result is improved;

2. this kind of pressure sensor for car sensitive in reaction, link up each other through oil pocket and compression chamber, pass through cooling pipeline with the cooling oil in the oil pocket and carry to the cooling intracavity, the cooling oil produces thrust upwards to the second movable stopper, make the second movable stopper upward movement, the second movable stopper promotes second piston rod upward movement simultaneously, second piston rod upward movement promotes second piston plate upward movement simultaneously, through second piston plate upward movement, the dwang that makes progress is promoted to the second piston plate, be provided with the movable block through the second piston inboard, can make the dwang rotate. The top end of the rotating rod is fixedly connected with the cleaning disc to rotate through the rotation of the rotating rod, the inner wall of the cavity is cleaned through the rotation of the rotating rod, and meanwhile, oil is prevented from flowing into one end of the rotating disc from a gap through the arrangement of the isolation net;

3. this kind of pressure sensor for car that reaction is sensitive, rotate through setting up the clearance dish, the rotary disk that can make clearance dish top rotates, can make the post that slides in the helicla flute through the rotary disk rotation, can make the post that slides along hindering the strip and remove at the horizontal direction, slide along hindering the strip outside through the slip post and can make thereby change the resistance value size, the pressure size of air inlet pressure is measured to the size that changes the electric current simultaneously, can effectively solve and now make resistance displacement with the tympanic membrane situation through the diaphragm, it has the location inaccurate, the reaction is sensitive inadequately, unable accurate problem of measuring of carrying out.

Drawings

FIG. 1 is a schematic perspective view of a pressure sensor for an automobile with sensitive response according to the present invention;

FIG. 2 is a schematic cross-sectional view of a pressure sensor for an automobile with a sensitive response according to the present invention;

FIG. 3 is a schematic structural diagram of a chassis of a pressure sensor for an automobile with sensitive response according to the present invention;

FIG. 4 is a schematic structural diagram of a rotary plate of a pressure sensor for an automobile with sensitive response according to the present invention;

FIG. 5 is a schematic structural diagram of a cleaning plate of a pressure sensor for an automobile with sensitive response according to the present invention;

FIG. 6 is an enlarged schematic structural diagram of a point B of the pressure sensor for an automobile with sensitive response according to the present invention;

fig. 7 is an enlarged structural diagram of point a of the pressure sensor for an automobile with sensitive response according to the present invention.

In the figure: 1. a housing; 2. a connector; 3. an air inlet; 4. a cavity; 5. a first movable plug; 6. a first piston rod; 7. a first spring; 8. a piston plate; 9. a compression chamber; 10. a communication port; 11. a second compression chamber; 12. an oil chamber; 13. a cooling chamber; 14. a second movable plug; 15. cleaning the disc; 16. rotating the disc; 17. a potentiometer; 18. a fixing plate; 19. a piston head; 20. a chassis; 21. a movable post; 22. a baffle plate; 23. a card slot; 24. a spring bar; 25. a second spring bar; 26. a third movable plug; 27. a third movable column; 28. a third piston plate; 29. a cooling duct; 30. cooling oil; 31. a second fixing plate; 32. a second piston rod; 33. a second piston plate; 34. a second spring; 35. rotating the rod; 36. connecting columns; 37. a fixed mount; 38. a helical groove; 39. a sliding post; 40. and (4) blocking the strips.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Referring to fig. 1 to 7, the present invention provides a technical solution: a pressure sensor sensitive in reaction for an automobile comprises a shell 1, a connector 2 is fixed at the bottom end of the shell 1, a threaded connector is arranged on the outer side of the connector 2, an air inlet 3 is arranged at the bottom end of the connector 2, a cavity 4 is arranged in the air inlet 3, a first movable plug 5 is arranged in the cavity 4, a first piston rod 6 is fixedly arranged at the top end of the first movable plug 5, a first spring 7 is sleeved on the outer side of the first piston rod 6, a first piston plate 8 is fixedly arranged at the top end of the first piston rod 6, a compression cavity 9 is arranged at the top of the first piston plate 8, a communication port 10 is arranged on one side of the top of the compression cavity 9, the communication port 10 is fixedly connected with a second compression cavity 11, an oil cavity 12 is arranged at the top end of the second compression cavity 11, the oil cavity 12 is fixedly connected with a cooling cavity 13, a second movable plug 14 is arranged in the cooling cavity 13, a cleaning disc 15 is arranged at the top end of the cleaning disc 16, the rotary disk 16 is provided with a potentiometer 17 on one side.

Referring to fig. 2, a fixed plate 18 is disposed between the first movable plug 5 and the first piston plate 8, two sets of first piston rods 6 are disposed, the two sets of first piston rods 6 are symmetrically mounted on two sides of the top end of the first movable plug 5 along the center of the cavity 4, the first piston rods 6 penetrate through one side of the top end of the fixed plate 18 and are connected to the first piston plate 8, the first piston rods 6 are movably connected to the fixed plate 18, a first spring 7 is sleeved on one side of each of the first piston rods 6, which is close to the bottom end of the fixed plate 18, and when gas enters the cavity 4 through the gas inlet 3 by disposing the first movable plug 5. The first movable stopper 5 of gaseous promotion moves, has first piston rod 6 through 5 top fixed mounting on the first movable stopper, can make first movable stopper 5 promote the first piston plate 8 upward movement of 6 top fixed mounting on first piston rod, can compress the air in the compression chamber 9 through 8 upward movement of first piston plate.

Referring to fig. 2 and 6, a piston head 19 is disposed on one side in a compression chamber 9, the piston head 19 includes a base plate 20, a movable column 21 and a blocking piece 22, a blocking slot 23 is disposed on one side of the top of a communication port 10, two sets of blocking slots 23 are disposed, the two sets of blocking slots 23 are respectively symmetrical along the central axis of the compression chamber 9, spring strips 24 are disposed in the two sets of blocking slots 23, the bottom ends of the spring strips 24 are fixedly connected with the movable column 21, the blocking piece 22 is fixedly mounted on one side of the movable column 21 close to the compression chamber 9, the movable column 21 is fixedly connected with the base plate 20 through one side of the communication port 10, a second spring strip 25 is sleeved on the bottom end of the movable column 21, the diameters of the two ends of the movable column 21 are larger than the diameter of the middle position, the interior of the compression chamber 9 can be compressed by setting a first piston plate 8 to move upwards, the base plate 20 can move upwards, the base plate 20 pushes the movable column 21 fixedly mounted on the top end of the base plate 20 to move upwards, through activity post 21 upward movement, can make activity post 21 to draw-in groove 23 internal motion, all be greater than the intermediate position diameter through setting up activity post 21 both ends diameter, can make intercommunication mouth 10 and compression chamber 9 link up each other, link up each other through intercommunication mouth 10 and compression chamber 9, can make second compression chamber 11 and compression chamber 9 link up each other.

Referring to fig. 2, two sets of the second compression chamber 11 and the oil chamber 12 are provided, the second compression chamber 11 and the oil chamber 12 are symmetrically installed on two sides of the outer wall of the cooling chamber 13 along the center line of the cooling chamber 13, a third movable plug 26 is provided between the second compression chamber 11 and the oil chamber 12, a third movable column 27 is fixedly connected to the top end of the third movable plug 26, a third piston plate 28 is fixedly installed on the top end of the third movable column 27, the oil chamber 12 is provided on the top of the third piston plate 28, a cooling pipe 29 is fixedly connected to one side of the oil chamber 12, a cooling chamber 13 is fixedly connected to the other end of the cooling pipe 29, the oil chamber 12 and the cooling chamber 13 are communicated with each other through a cooling pipe 29, cooling oil 30 is provided in the oil chamber 12 and the cooling chamber 13, the second compression chamber 11 and the compression chamber 9 are communicated with each other, the compression chamber 9 can be compressed by the upward movement of the first piston plate 8, so that the compression chamber 9 applies air pressure to the second compression chamber 11 through the communication port 10, the air pressure in the second compression cavity 11 pushes the third movable plug 26 upwards to generate an upward pushing force, so that the third piston plate 28 can move upwards, the third piston plate 28 pushes the third piston plate 28 to move upwards through the upward movement of the third piston plate 28, the cooling oil 30 in the oil cavity 12 is conveyed into the cooling cavity 13 through the cooling pipeline 29, and the cooling cavity 13 is cooled through the arrangement of the cooling oil 30.

Referring to fig. 2, a second fixed plate 31 is fixedly installed in the cooling chamber 13, a second movable plug 14 is disposed on one side of the bottom of the second fixed plate 31, second piston rods 32 are fixedly installed on both sides of the top end of the second movable plug 14, the second piston rods 32 penetrate through the second fixed plate 31 and are fixedly connected with a second piston plate 33, the second piston rods 32 are movably connected with the second fixed plate 31, second springs 34 are sleeved between the second piston plates 33 and the second fixed plate 31 on one side of the second piston rods 32, cooling oil 30 is delivered into the cooling chamber 13 through a cooling pipeline 29, the cooling oil 30 generates an upward thrust on the second movable plug 14, so that the second movable plug 14 moves upward, the second movable plug 14 pushes the second piston rods 32 to move upward, and the second piston rods 32 move upward and push the second piston plate 33 to move upward.

Referring to fig. 2, 5 and 7, a cleaning plate 15 is disposed on the top of the second piston plate 33, a rotating rod 35 is fixedly connected to the bottom end of the cleaning plate 15, the rotating rod 35 penetrates through one side of the top end of the second piston plate 33, a movable block 41 is disposed in the second piston plate 33, a threaded structure is disposed at a contact portion between the rotating rod 35 and the movable block 41, a scraping plate is disposed on the outer side of the cleaning plate 15, an isolation net is disposed at the bottom of the cleaning plate 15, the second piston plate 33 moves upwards, the second piston plate 33 pushes the upwards rotating rod 35, and the movable block 41 is disposed in the second piston plate 33, so that the rotating rod 35 can rotate. Rotate through dwang 35 and can make dwang 35 top fixed connection clearance dish 15 rotate, rotate through dwang 35 and clear up the cavity inner wall, prevent through setting up the separation net that oil from flowing into to rotary disk 16 one end in the gap simultaneously.

Referring to fig. 2, 4 and 7, the potentiometer 17 includes a sliding column 39 and a blocking bar 40, a connecting column 36 is fixedly installed at a central position of a top end of the cleaning disc 15, a fixed frame 37 is fixedly connected to a top end of the connecting column 36, a rotating disc 16 is fixedly installed at a top end of the fixed frame 37, a spiral groove 38 is provided at one side of a top end of the rotating disc 16, a sliding column 39 is provided in the spiral groove 38, a blocking bar 40 is provided at one side of the sliding column 39, two sets of blocking bars 40 are provided, one end of each set of blocking bar 40 penetrates through one side of the sliding column 39, the other end of each blocking bar 40 penetrates through one side of an inner wall of the housing and is connected to the chip, the blocking bar 40 is connected to the sliding column 39 in a sliding manner, the rotating disc 16 at the top of the cleaning disc 15 can be rotated by arranging the cleaning disc 15, the sliding column 39 in the spiral groove 38 can be moved along the blocking bar 40 in a horizontal direction by the rotating disc 16, the sliding column 39 can be slid along an outer side of the blocking bar 40 to change a resistance value, and simultaneously, the magnitude of the current is changed to measure the pressure magnitude of the intake pressure.

The working principle is as follows: when the pressure sensor sensitive in reaction for the automobile is used, the connector 2 is fixedly connected with a main pipe of a rear door of an automobile throttle valve, when gas enters a cavity 4, the first movable plug 5 is pushed to move and the first piston plate 8 moves upwards to compress the interior of a compression cavity 9, meanwhile, a chassis 20 and a movable column 21 move upwards, the communication port 10 and the compression cavity 9 can be communicated with each other through the chassis and the movable column 21 moving upwards, the communication port 10 and the compression cavity 9 are communicated with each other through the communication port 10, the compression cavity 9 can apply air pressure to the second compression cavity 11 through the communication port 10, meanwhile, the air pressure in the second compression cavity 11 upwards generates an upwards driving force to the third movable plug 26 and the third piston plate 28, cooling oil 30 in an oil cavity 12 is conveyed into a cooling cavity 13 through a cooling pipeline 29, the interior of a cooling wall is cooled through the cooling oil 30, and the cooling oil 30 is conveyed into the cooling cavity 13 through the cooling pipeline 29, the cooling oil produces thrust upwards to second movable stopper 14, promote the upward movement of second piston plate 33 and promote, can make dwang 35 rotate, rotate through dwang 35 and clear up the cavity inner wall, prevent that oil from flowing into to rotary disk 16 one end in the gap through setting up the separation net, can make the rotary disk 16 at clearance dish 15 top rotate, can make the sliding column 39 in the helicla flute 38 through the rotary disk 16 rotation, can make sliding column 39 remove at the horizontal direction along hindering strip 40, slide along hindering strip 40 outside through sliding column 39, thereby change the resistance value size, change the size that the size of electric current measured the oil pressure simultaneously, this kind of automobile pressure sensor that reacts sensitively, it is accurate to possess the location, the reaction is sensitive, have and can carry out accurate measurement advantage.

Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.