JPH048609A - Air pressure sensing device for tire - Google Patents

Abstract

PURPOSE:To enlarge change of magnetic flux without using centrifugal force and facilitate return to the initial state of rotary magnet by rotating the rotary magnet on the basis of differential pressure between a sealed pressure chamber and a tire, changing the relative position with a pair of stationary magnets, stopping the rotary magnet, and sensing the direction of the pole at the time. CONSTITUTION:A shaft 139 is moved to the left in the attached illustration while the tire pressure is normal, and a magnetic body 165 is in the attached state by No.1 magnet 157. A magnetism amplifying means 161 confronts the S-pole of a magnet 159, and a sensing means senses this S-pole. When the tire pressure sinks to cause the differential pressure from a pressure chamber 163 to exceed the force of No.1 magnet 157 to attract the magnetic body 165, the two members separate from each other, and the differential pressure from a displacing means 135 moves it to the right. Now another magnetic body 167 is attracted by the magnet 159, and the magnetism amplifying means 161 confronts the N-pole of the No.1 magnet 157, and sensing means senses it and issues information about drop of the air pressure. Thus the width of change in the magnetic flux can be enlarged without resorting to centrifugal force.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a tire air pressure detection device for detecting tire air pressure.

[Conventional technology]

Conventionally, as a tire pressure detection device, the
As shown in Publication No. 39, there is a known device in which a magnetic body moves due to centrifugal force when the air pressure of a tire decreases, this is detected by a magnetic force detection device, and the magnetic body is returned to its original position by being attracted by a magnet 7). Ta.

[Problem to be solved by the invention]

However, in this conventional tire pressure detection device, in order to accurately detect a decrease in tire air pressure, that is, to increase the change in the magnetic flux of the magnetic body when the tire air pressure decreases, this magnetic body is applied with centrifugal force. It was moved further. For this reason, there has been a problem in that a decrease in tire air pressure cannot be detected when no centrifugal force is acting on the tire.

The present invention has been made in view of the above-mentioned problems, and aims to provide a tire pressure detection device that can increase the change in magnetic flux without using centrifugal force, and can easily restore the magnetic body. .

[Means to solve the problem]

In order to achieve the above object, the present invention includes a displacement means that is displaced according to the air pressure of the tire.

a housing having the displacement means; a pressure chamber formed by the housing and the displacement means and sealed with gas at a predetermined pressure; and a pressure difference between the predetermined pressure of the gas in the pressure chamber and the air pressure of the tire. a rotatable rotating magnet that is provided to be reciprocally movable within the pressure chamber in conjunction with the displacement means; and a pole that is provided parallel to the reciprocating direction of the cough rotating magnet and that faces the rotating magnet. first and second fixed magnets that are different from each other; and a detection means that detects a change in the polar direction of the rotary magnet, and when the air pressure of the tire is greater than a predetermined value, one of the rotary magnets is and the first fixed magnet attract each other, and when the air pressure of the tire is below a predetermined value, the rotating magnet rotates and the other pole of the rotating magnet attracts the second fixed magnet. It has a structure that attracts each other.

The present invention also includes: a displacement means that is displaced in accordance with the air pressure of the tire; a housing having the displacement means; a pressure chamber formed by the housing and the displacement means and sealed with gas at a predetermined pressure; a shaft provided to be able to reciprocate within the pressure chamber in conjunction with the displacement means based on a differential pressure between a predetermined pressure and the air pressure of the tire; a rotating magnet that is rotatably provided around the shaft; first and second fixed magnets that are provided parallel to the reciprocating direction of the shaft and have magnetic poles in mutually different directions; detection means for detecting the direction of a pole of a magnet, and when the air pressure of the tire is greater than a predetermined value, one pole of the rotary magnet and the first fixed magnet attract each other, and the air pressure of the tire is If is less than a predetermined value, the rotary magnet may rotate so that the other pole of the rotary magnet attracts the second fixed magnet.

Further, the present invention further comprises: a displacement means that is displaced according to the air pressure of the tire; a housing having the displacement means; a pressure chamber formed by the housing and the displacement means and sealed with gas at a predetermined pressure; first and second magnets, which are provided so as to be reciprocally movable within the pressure chamber in conjunction with the displacement means based on a differential pressure between a predetermined pressure and the air pressure of the tire, and have magnetic poles in mutually different directions; 1
and a second magnet is provided within the pressure chamber at a predetermined distance from both ends of the first and second magnets in the reciprocating direction of the magnet, and when the air pressure of the tire is greater than a predetermined value, the first When the air pressure of the tire is below a predetermined value, the displacement means is displaced by the differential pressure between the predetermined pressure of the gas in the pressure chamber and the air pressure of the tire, and the tire is attracted to the second magnet. It may be configured to include a magnetic body and a detection means for detecting a change in the direction of the magnetic pole due to the reciprocating motion of the first and second magnets.

Furthermore, the displacement means may be an elastic member that maintains airtightness.

Furthermore, the housing may include an air pressure relaxation means that is provided in the housing and alleviates sudden fluctuations in air pressure that the air pressure of the tire applies to the displacement means.

Further, the vehicle may be provided with a shutoff means that shuts off the air in the tire and the air acting on the displacement means when the tire pressure exceeds a reference value.

Further, the direction of the reciprocating motion may be perpendicular to the direction of the centrifugal force of the tire.

[Effect]

Claim 1 having the above configuration. Or, in the tire air pressure detection device described in 2, when the tire air pressure is higher than a predetermined value, the displacement means is displaced according to the differential pressure between the tire air pressure and the predetermined pressure of the gas in the pressure chamber. , the rotating magnet performs reciprocating motion in conjunction with this. In this case, the attractive force between one pole of the rotating magnet and the first fixed magnet is greater than the repulsive force between one pole of the rotating magnet and the second fixed magnet, so the rotating magnet The state in which one pole and the first fixed magnet are attracted to each other continues.

Next, when the tire air pressure falls below a predetermined value, the displacement means is displaced according to the differential pressure between the tire air pressure and the predetermined pressure of the gas in the pressure chamber, and in conjunction with this, the rotating magnet moves and rotates. The repulsive force between one pole of the rotating magnet and the second fixed magnet is greater than the attractive force between one pole of the rotating magnet and the first fixed magnet, so the rotating magnet rotates and rotates. The other pole of the magnet attracts the second fixed magnet. In this state, the attractive force between the other pole of the rotating magnet and the second fixed magnet is greater than the repulsive force between the other pole of the rotating magnet and the first fixed magnet. When listening, the state in which the second field fixed magnet and the magnet continue to attract each other continues. The detection means detects a change in the direction of the pole due to rotation of the rotary magnet.

Further, in the tire air pressure detection device according to claim 3, when the tire air pressure is higher than a predetermined value, the displacement means is displaced according to the tire air pressure, and the first displacement means is operated in conjunction with the displacement means. The second magnet is attracted to the magnetic body, and the second magnet is not attracted to the magnetic body.

Next, when the air chamber of the tire becomes lower than a predetermined value, the first
The thrust of the displacement means due to the differential pressure between the predetermined pressure of the gas in the pressure chamber and the tire air pressure is greater than the attraction force between the magnet and the magnetic body, and therefore the displacement means moves in the other direction. , the second magnet is attracted to the magnetic body. Since the first magnet and the second magnet have different magnetic pole directions, the detection means detects a change in the magnetic pole direction.

In addition, claims 1 and 2. Or, in the tire pressure detection device described in 3, if the displacement means is constituted by an elastic member that maintains airtightness, the rotating magnet or the first and second The second magnet moves more quickly due to its elasticity.

Further, even if the air pressure of the tire suddenly fluctuates, the air pressure relaxation means relieves the sudden fluctuation and applies it to the displacement means.

In addition, when a cutoff means is provided, when the tire air pressure exceeds the standard value, this cutoff means cuts off the air in the tire and the air acting on the displacement means, so even if the tire air pressure fluctuates, the displacement means will not work. It will no longer be displaced.

Furthermore, since the reciprocating direction of the rotating magnet or the first and second magnets is perpendicular to the direction of the centrifugal force of the tire, even if centrifugal force is generated in the tire, the rotating magnet or the first and second magnets It does not affect the reciprocating movement of the magnet in step 2.

[Example] The present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a first embodiment of the present invention, in which the present invention is applied to a normal tire. 3 is a tire, and the rim 3 is fixed to the wheel shaft 7 with a hole nut 5. The brake drum 9 is welded to a plate 11, and the plate 11 is fixed to the wheel axle 7 with bolts (not shown).

The inner ring of the hair ring 13 and the wheel shaft 7 are fixed with a nut 15. The bearing housing 17 and the cover plate 19 are fixed to the hub 21 together with the outer ring of the hair ring 13 by bolts (not shown). The lower end of the shock absorber 23 is fixed to the hub 21 with a bolt 25, and the upper end (not shown) of the shock absorber 23 is fixed to the vehicle body side. One end of the suspension arm 27 is rotatably supported by the hub 21 by a bolt 28, and a lower end (not shown) of the suspension arm 27 is supported by the vehicle body. Reference numeral 29 denotes a pressure detection section which is a main part of this embodiment, and is fixed inside the tire by a fixing means 30, the details of which will be described later. 31 is a detection means, which detects a change in the direction of the magnetic pole due to the reciprocating motion of the first and second magnets, which will be described later, converts it into an electric signal, and sends the signal to a control circuit 35 as a determination means via a wire harness 33. Send out electrical signals. 36 is a battery, and 38 is a switch. In FIG. 1, tires 1. Rim 3. Wheel nut 5, wheel axle 7. Brake drum9. Plate 11 nuts 15. Pressure detection section 29
．． The inner ring of the hair ring 13 rotates while the vehicle is running, but the other parts are supported by the vehicle body and do not rotate.

FIG. 2 is a detailed sectional view of the pressure sensing section 29.

101 is a cylindrical housing made of non-magnetic metal such as aluminum, and both ends 103 and 105 are constricted at right angles. 107 and 109 are bases made of stainless steel or aluminum, and the housing 10
O-rings 111 are provided at both ends of 1 to maintain airtightness.
, 113 and gaskets 115 and 117 made of copper or aluminum. base 107
An air pressure relief means 119 is provided at the end of the air pressure relief means 119 .

This air pressure relaxation means 119 is composed of a filter made of sintered metal, and prevents the air pressure inside the base 107 from fluctuating drastically even if the tire air pressure fluctuates rapidly. .

Reference numeral 123 denotes a check valve, one end of which discharges from inside the base, and the other end biased by a coil spring 127 via a circular tail 125. This coil spring 127 always urges the air pressure relief means 119 and the check valve 123 in a direction in which they are pressed together. 129
is a chamfered portion of the check valve 123, and this chamfered portion 1
29 forms a communication hole 131 in the base 107, and air enters and exits the base through this communication hole 131. The distal end 124 of the check valve 123 is chamfered and is in contact with a displacement means 135, for example a bellows, and it is the displacement means 135 that biases the check valve 123 in the right direction in FIG. A coil spring 127 biases the check valve 123 toward the left in FIG.

A rubber grommet 133 is provided on the check valve 123, and when the tire air pressure increases abnormally and exceeds the reference value, the displacement means 135 moves to the left in FIG. Chie 7 Riben 1
23, the grommet 133 also moves to the left to close the communication hole 131 and prevent the air inside the tire from passing through the communication hole 131. This coil spring 127. Check valve 123. The grommet 133 constitutes a blocking means. The displacement means 135 is a bellows made of metal such as nickel and has a bag shape, and its end 135a is fixed to the base 107 with an airtight fixing means such as adhesive. Airtightness is maintained between the air inside the tire that enters through the hole 131 and the gas inside the pressure chamber 163, which will be described later. 137 is a connecting member for interlocking the displacement means 135 and the soyaft 139, and its detailed shape is shown in FIGS. 3(a) and 3(
'b). The connecting member 137 is made of a non-magnetic metal such as stainless steel, and has a shape similar to a cylinder covered with a lid, and has a notch 137a and a protrusion 137 inside the cylinder.
It has b. Here, Fig. 311a (a) is a perspective view of the connecting member 137 seen from the notch 137a, and Fig. 3 (g)) is a perspective view seen from the opposite direction.

As can be seen from FIG. 2, the displacement means 135
It is fixed to the convex portion 137b of No. 37 by a fixing means such as adhesive.

The resin mold 151 is formed by molding resin onto the shaft 139, and is made of stainless steel.
It has grooves 151a and 151b for inserting the and 155. Reference numeral 157 indicates a first magnet, and reference numeral 159 indicates a second magnet, in which a permanent magnet on a ring is fixed to the shaft 139 by a resin mold 151. Here, the directions of the magnetic poles of the first magnet 157 and the second magnet 159 are different from each other. For example, as shown in FIG. The north pole is the north pole, and the second magnet 159 is the south pole. The magnetic amplification means 161 has the shape of two stacked cylinders of two sizes, and is made of iron.

The small diameter portion 161a is the first magnet 157 or the second magnet 1.
On the other hand, the large diameter portion 161b is provided so as to face the detection means 31.

Note that this magnetic amplification means 161 is not limited to this shape,
Any shape is sufficient as long as the area facing the first or second magnet 157, 159 is small and the area facing the detection means 31 is large; thereby, the magnetism of the first or second magnet can be amplified. can.

The pressure chamber 163 is a sealed space formed by the housing 101, the base 109, and the displacement means 135, and has a pressure that determines a decrease in tire air pressure and a pressure that is the center value of the normal pressure (1.7 kgf/cTIG in this example). ) is filled with air or inert gas. Magnetic materials 165 and 167
is a stator provided in the housing 101 at a predetermined distance from the end faces of the first magnet 157 and the second magnet 159, and may be made of any magnetic material. In this case, iron is used.

FIG. 4 shows a perspective view of a plate spring 141 made of stainless steel. As can be seen from FIG. 4, a hole 143 is provided at the center of the leaf spring 141, and the tip 139a of the shaft 139 is slidably inserted into this hole 143, as shown in FIG. , the leaf spring 141 is in a bent state.

FIG. 5 shows a shaft 139 and a first magnet 157 fixed to the shaft 139 by a resin mold 151.
FIG. 3 is a perspective view showing a second magnet 159 and the like. This fifth
In the figure, three to four grooves 151a and 151b are provided, and a stopper portion 151C is formed by resin molding near the tip 139a of the shaft 139. This stopper part 1.51c is inserted into the notch part 137a during assembly, and then the shaft 139 is inserted into the notch part 137a.
By rotating the shaft 139 by 0°, the shaft 139 is prevented from coming off the connecting member 137.

In FIG. 2, the cylinder 145 is made of aluminum;
The purpose of assembly is to improve performance. That is,
The assembly is sometimes carried out after the magnetic body 167 is assembled into the housing 101, and then the connecting member 1 is assembled into the cylinder 145.
37. Displacement means 135, check valve 123. base 10
7. Insert the O-ring 111 etc. together with the cylinder 145 into the housing 101 from the right side in FIG.
The shaft shown in FIG. 5 is inserted from the left side in FIG. 2, and the connecting member 137 and the damper portion 151C are engaged with each other.

Next, the detailed configuration of the detection means 31 is shown in FIG. In FIG. 6, 61 is a case made of a non-magnetic metal such as an aluminum alloy, and 63 is a magnetic core. Iron or non-excited ferrite is used as the magnetic material. The coil 65 is an insulated conductive wire that is connected to the magnetic material 63 via a resin bobbin 67.
The ends of the conductive wire are tied together by a metal fitting 69.
They are tied together with a wire harness 33, each of which is electrically connected to a wire berth. With the above configuration, the detection means 31 can detect changes in external magnetism and convert them into electrical signals.

Further, both ends of the conductive wire may be electrically connected together with the two wire harnesses 33 by a connecting means such as soldering using metal terminals fixed to the resin bobbin.

Next, the operation of this embodiment configured as described above will be explained. When the tire pressure is normal (e.g. 1.8kgf/
c-tlTc), as shown in FIG. 2, the shaft 139 moves to the left in FIG.
The magnet 157 and the magnetic body 165 are attracted to each other. In this state, the magnetic amplification means 161 faces the S pole of the second magnet 159, so the magnetic pole detected by the detection means 31 is the S pole.

Next, the tire air pressure decreases, and the determination pressure for tire air pressure decrease (in this example, 1.6 kg f /cn
When the temperature drops below G, the pressure of the gas in the pressure chamber 163 and the communication hole 1
The thrust force of the displacement means due to the differential pressure between the tire air pressure and the tire air pressure acting on the displacement means 135 through 31 exceeds the force of attracting the first magnet 157 and the magnetic body 165 to each other, and the first magnet 157
and the magnetic body 165 separates. First magnet 157 and magnetic body 1
65 is separated, due to the spring force of the displacement means 135 and the differential pressure between the pressure inside the pressure chamber 163 and the tire air pressure,
The displacement means 135 moves rapidly to the right in FIG. As the displacement means 135 rapidly moves to the right, the shaft 139 also moves to the right in conjunction with it, and the second magnet 159 and the magnetic body 167 are attracted to each other. In this state, the magnetic amplification means 161 is in a state facing the north pole of the first magnet, and the magnetic pole detected by the detection means changes to the north pole. By detecting this change in magnetic pole, the determining means 35 determines whether the tire air pressure has decreased.

The air pressure relaxation means 119 is designed to directly respond to pulsations in the tire air pressure that occur when the vehicle runs on a bumpy road, in other words, when the tire air pressure changes suddenly. This is to prevent it from being transmitted to the displacement means 135.

As a result, even when the vehicle runs on a bumpy road,
Misjudgment, that is, it is not determined that the tire air pressure is normal when the tire air pressure is normal, or it is not determined that the tire air pressure is normal when the tire air pressure is decreased.

Next, a check valve 123 serving as a shielding means. Coil spring 127. The function of the grommet 133 will be explained. Even if the tire pressure is normal or has fallen below the judgment pressure for low tire pressure,
The coil spring 127 pushes the air pressure relief means 119 and the check valve 123 together, and the tip 1 of the check valve 123
24 is pressed against the displacement means 135, the grommet 133 is separated from the communication hole 131, so the air pressure inside the tire acts on the displacement means 135 through the communication hole 131. Here, if you accidentally overinflate the tire when refilling the air, and as a result, the tire air pressure becomes, for example, 10 atmospheres, the tire air pressure will directly act on the displacement means 135 if there is no blocking means. As a result, problems such as damage to the displacement means 135 and a decrease in the restoring force of the spring member occur.However, in this embodiment, when the air pressure inside the tire reaches a high pressure such as 10 atmospheres, the shaft in FIG. 139 moves to the left, the magnetic body 165 and the first magnet 157 attract each other, and although the shaft cannot move further to the left, the displacement means 135 moves to the left, and the connecting member 137 is connected to the leaf spring. As a result of moving leftward while further bending valve 141, check valve 123
However, when the check valve 123 reaches a position where the grommet 133 closes the communication hole 131, it does not move further to the left and moves the grommet 133 to the base 107.
The above-mentioned problem does not occur because the air pressure of the tire does not act on the displacement means 135 by closing the communication hole 131 in close contact with the displacement means 135.

In this embodiment, after the air pressure of the tire has decreased and the second magnet 159 is attracted to the magnetic body 167, and after the determining means 35 determines that the air pressure has decreased, the driver When refilled, the air pressure relief means 11
9 and the communication hole 131, the air pressure inside the tire acts on the displacement means 135, and the air pressure of the tire becomes 1.8 f.
kg/cIIIG or more, the differential pressure between the tire air pressure and the pressure chamber 163 becomes larger than the sum of the biasing force of the displacement means 135 and the attractive force of the second magnet 159 and the magnetic body 167. The magnet 159 and the magnetic body 167 are separated, and the shaft 139 moves to the left in FIG. 2 together with the displacement means 135, and the first magnet 157 and the magnetic body 1
65, and the tire can be returned to its initial state with normal air pressure. In this embodiment, the displacement means 135 is configured such that the tire air pressure is 1.7 kg.
In the case of f/ctllG, that is, when the tire air pressure and the pressure in the pressure chamber 163 are equal, the biasing amount of the spring is set to be O.

Here, the attraction force between the first or second magnet and the magnetic body is g
, the stroke of the connecting member 137 is χ, and the displacement means 135 is
The thrust force of the connecting member 137 is f, and the thrust force of the connecting member 137 is F, and FIGS. 7 and 8 show the respective relationships when the tire air pressure is 1.8 kg/cnG and when the tire air pressure is 1.6 kgf/cnG. Shown below.

In the embodiment described above, the pressure sensing section 29 is mounted so that the reciprocating direction of the shaft 139 is perpendicular to the plane of the paper of FIG. 1, as shown in FIG. However, the present invention is not limited to this, and any direction may be used as long as the centrifugal force does not act on the reciprocating motion of the shaft. For example, as shown in FIG. 9, the reciprocating direction of the shaft is the left-right direction in FIG. The pressure detection section 29 may be provided in the pressure detection section 29. In addition, in the 9th episode, the pressure sensing section 2
9 is installed near the air valve 169 for filling air in the tire, and when replacing a tire, tools are not inserted near the near valve 169, so there is no risk of damage to the pressure detection part 29. This has the effect of lowering the possibility of

Next, a second embodiment of the present invention will be described using FIGS. 10 to 19. In this embodiment, the pressure detection section 29 in the first embodiment is replaced with a pressure detection section 200, and since the other configurations are the same, the explanation thereof will be omitted. FIG. 10 is a detailed cross-sectional view of the pressure sensing section 200,
The same or equivalent parts as in the first embodiment are given the same reference numerals,
The last part is omitted. In FIG. 10, 202 is a stepped cylindrical connecting member, with a central hole 20 in the center.
4 is provided and fixed by welding or soldering to the displacement means 135. A tip end 208 of a shaft 206 is inserted into the center hole 204 of the connecting member 202 and troweled. The shaft 206 has bearings 210, 212
It is supported by and can reciprocate in the left-right direction in FIG. 214 and 216 are retainers of the bearing 210, and 218 and 220 are balls of the bearing 210. 222 is a fan-shaped stop collar provided on the shaft 206; 224 is a stainless steel E-ring fixed to the constriction 226 of the shaft 206; There is. A cylindrical ring 228 made of metal can slide on the shaft 206, and can reciprocate and rotate with the rotating magnet 232 due to the resin mold 230. Note that both ends of this resin mold 230 and the stopper 222. The distance between the E-ring 224 and the E-ring 224 is approximately 0.05 mm. In the housing 101, a first fixed magnet 234 and a second fixed magnet 236 are provided at positions facing the rotating magnet 232.

In this embodiment, the first fixed magnet 234 and the second fixed magnet 2
Although the fixed magnets 36 are provided in contact with each other, the fixed magnets are not limited to this, and the fixed magnets may be provided separated by a predetermined distance, or a magnetic shielding member may be provided in between.

Fig. 11 shows a front view of the shaft 2o6, Fig. 12 shows a right side view of Fig. 11, and Fig. 13 shows the A-A of Fig. 11.
A cross-sectional view is shown. Further, FIG. 14 shows a detailed partial sectional view of the vicinity of the rotating magnet 232, FIG. 15 shows a right side view of FIG. 14, and FIG. 16 shows a BB sectional view of FIG. 14. .

In FIG. 16, the resin mold 230 is also formed in a notched main portion 229 of a part of the outer circumference of the cylindrical ring 228, thereby making the connection between the rotary magnet 232 and the cylindrical ring 228 stronger. 14 and 15, a part of the resin mold 230 is provided with a protrusion 231 as a stopper. This protrusion 231 is the stopper surface 2 of the stopper 222 shown in FIGS. 12 and 13.
If the rotating magnet 232 hits either of 22a and 222b, it will not rotate any further.

Next, the operation of the second embodiment of the present invention configured as described above will be explained using schematic diagrams 17 to 19.

If the tire pressure is normal (for example, 1.8 kgf
/cillG), as shown in FIG. 17(a), the rotating magnet 232 is located closer to the first fixed magnet 234 than the second fixed magnet 236; The force P between the N pole of the rotating magnet 232 and the S pole of the rotating magnet 232 attracts each other.
S poles of the first and second fixed magnets 236 and S poles of the rotating magnet 232
The sum (P, +P2) of the mutually repulsive force P2 of the poles is larger than the rightward bellows thrust F indicated by the arrow in the figure. In this state, P,>P2.

Next, the air pressure of the tire gradually decreases and F〉(PI+
P2), and when the herous 135 as a displacement means is displaced, the shaft 206 also moves to the right in FIG. 10 or FIG. It becomes 6kgf/c'IIIG,
When the rotating magnet 232 comes to the position shown in FIG. 18(a),
When the first fixed magnet 234 and rotating magnet 232 come together, the first
The attractive force P between the fixed magnet 234 and the rotating magnet 232 is smaller than the repulsive force P2 between the second fixed magnet 236 and the rotating magnet 232, so this repulsive force P2 causes the rotating magnet 2 to
As a result of the rotating magnet 232 being rotated by the rotational force applied to the rotating magnet 32, the state shown in FIGS. 19(a) and 19(b) is achieved. In this state, the attractive force P1 between the S pole of the second fixed magnet 236 and the N pole of the rotating magnet 232 is stronger than the repulsive force P2 between the Ni of the first fixed magnet 234 and the N pole of the rotating magnet 232. is large.

In this way, when the air pressure of the tire becomes less than a predetermined value, the rotating magnet 232 is reversed, so the detection means 31 detects the change in the polarity of this rotating magnet (in this embodiment, from the N pole to the S pole). ).

After that, if air is injected into the tire and the tire air pressure returns to normal, the driver can return to the normal initial state shown in FIG. 17(a) without any operation.

Note that the first example in the first and second embodiments described above
The second magnet, the rotating magnet, and the first and second fixed magnets may be composed of electromagnets.

〔Effect of the invention〕

As explained above, according to the invention described in claim 1 or 2, when the tire air pressure becomes below a predetermined value,
The rotating magnet rotates due to the attraction and repulsion between the first and second fixed magnets and the rotating magnet, and the detection means detects the change in the polar orientation of the rotating magnet, so the magnetic flux is In addition, since the attraction and repulsion of the first and second fixed magnets and the rotating magnet are used to return the rotating magnet to its initial state, the rotational magnet's Excellent effects can be achieved if recovery is easy.

Further, according to the invention described in claim 3, when the tire air pressure decreases and the first magnet and the magnetic body are once separated, the second magnet is The magnet and the magnetic body are attracted to each other, and the detection means detects the change in the orientation of the first and second magnetic poles. Therefore, it is possible to increase the change in magnetic flux when the tire air pressure decreases without using centrifugal force. can. In addition, when the tire is filled with air after it has been determined that the tire air pressure has decreased, the second
Since the first magnet and the magnetic body are separated from each other and the first magnet and the magnetic body are attracted to each other, an excellent effect is achieved in that a return means is not required.

In addition, if the displacement means is made of an elastic member that maintains airtightness, the direction of the magnetic pole changes more quickly, so even when the tire air pressure is around a predetermined value, the direction of the magnetic pole is ambiguous. This can be prevented.

In addition, when an air pressure relief means is provided, sudden changes in tire air pressure are not directly transmitted to the displacement means, so even when driving on a highly uneven road surface, the direction of the magnetic poles changes frequently, making accurate tire adjustment possible. Problems such as not being able to detect air pressure do not occur.

Furthermore, when the blocking means is provided, the displacement means will not be displaced even if the tire air pressure changes when the tire air pressure exceeds the reference value, so that the displacement means will not be damaged.

In addition, since the reciprocating direction of the rotating magnet or the first and second magnets is perpendicular to the direction of the centrifugal force of the tire, centrifugal force is generated in the reciprocating movement of the rotating magnet or the first and second magnets. The reciprocating motion is based only on the pressure difference between the tire air pressure and the predetermined pressure of the gas in the pressure chamber.

[Brief explanation of drawings]

FIG. 1 is a sectional view of essential parts showing the overall configuration of the first embodiment of the present invention, FIG. 2 is a detailed sectional view of the pressure detection section of the above embodiment,
FIG. 3(a) and the third appearance) are perspective views showing the shape of the connecting member in the above embodiment, FIG. 4 is a perspective view showing the shape of the leaf spring in the above embodiment, and FIG. 5 is a perspective view showing the shape of the plate spring in the above embodiment. 6 is a sectional view showing the detection means of the above embodiment, FIGS. 7 and 8 are characteristic diagrams for explaining the thrust of the connecting member in the above embodiment, and FIG. 9 is a sectional view showing the detection means of the above embodiment. FIG. 10 is a detailed sectional view of the pressure sensing portion of the second embodiment of the present invention, and FIG. 11 is a sectional view of the main part showing a modification of the above embodiment.
The front view of the shaft in the example, FIG. 12 is a right side view of FIG. 11, FIG. 13 is a sectional view taken along line A-A in FIG.
FIG. 4 is a detailed partial sectional view of the vicinity of the rotating magnet of the second embodiment, FIG. 15 is a right side view of FIG. 14, and FIG.
BB sectional view in Figure 4, Figures 17(a) to 19(b)
FIG. 2 is a schematic diagram for explaining the operation of the second embodiment. 31... Detection means, 35... Judgment means, 101...
・Housing, 119...Air pressure relaxation means, 123・
...Check valve, 127...Coil spring, 13
3... Grommet 135... Displacement means, 139.
...Nyaft 157...First magnet, 159...
Second magnet 163...pressure chamber, 165, 167...
Magnetic body, 206... Shaft, 232... Rotating magnet, 234... First fixed magnet, 236... Second fixed magnet.

Claims (7)

[Claims] (1) A displacement means that is displaced according to the air pressure of the tire, a housing having the displacement means, a pressure chamber formed by the housing and the displacement means and sealed with gas at a predetermined pressure, and the gas in the pressure chamber. a rotary magnet provided to be able to reciprocate within the pressure chamber in conjunction with the displacement means based on a differential pressure between a predetermined pressure of the rotary magnet and the air pressure of the tire; first and second fixed magnets that are provided and have different poles facing the rotating magnet; and a detection means that detects a change in the direction of the poles of the rotating magnet, and the tire has a predetermined air pressure. If the tire pressure is greater than the predetermined value, one pole of the rotary magnet and the first fixed magnet attract each other, and if the air pressure of the tire is less than a predetermined value, the rotary magnet rotates to prevent the rotation. A tire air pressure detection device characterized in that the other pole of the magnet attracts the second fixed magnet. (2) a displacement means that is displaced according to the air pressure of the tire; a housing having the displacement means; a pressure chamber formed by the housing and the displacement means and sealed with gas at a predetermined pressure; and the gas in the pressure chamber. a shaft provided to be able to reciprocate within the pressure chamber in conjunction with the displacement means based on a differential pressure between a predetermined pressure of the tire and the air pressure of the tire; and axial movement of the shaft with respect to the shaft is restricted; a rotating magnet rotatably provided around the shaft; first and second fixed magnets provided parallel to the reciprocating direction of the shaft and having magnetic poles in mutually different directions; detection means for detecting the orientation of a plate of a moving magnet, and when the air pressure of the tire is greater than a predetermined value, one pole of the rotating magnet and the first fixed magnet attract each other, A tire air pressure detection device characterized in that when the air pressure is below a predetermined value, the rotary magnet rotates so that the other pole of the rotary magnet attracts the second fixed magnet. (3) a displacement means that is displaced according to the air pressure of the tire; a housing having the displacement means; a pressure chamber formed by the housing and the displacement means and sealed with gas at a predetermined pressure; and the gas in the pressure chamber. first and second magnets, which are provided so as to be able to reciprocate within the pressure chamber in conjunction with the displacement means based on the differential pressure between the predetermined pressure of the tire and the air pressure of the tire, and have magnetic poles in different directions; A second magnet is provided within the pressure chamber at a predetermined distance from both ends of the first and second magnets in the reciprocating direction of the first and second magnets, and when the air pressure of the tire is greater than a predetermined value, When the air pressure of the tire is below a predetermined value, the displacement means is displaced by the differential pressure between the predetermined pressure of the gas in the pressure chamber and the air pressure of the tire, and the second magnet A tire air pressure detection device comprising: a magnetic body that attracts; and a detection means that detects a change in the direction of the magnetic pole due to reciprocating motion of the first and second magnets. (4) The tire air pressure detection device according to claim 1, 2, or 3, wherein the displacement means is an elastic member that maintains airtightness. (5) Claims 1 and 2 are characterized in that the housing is provided with an air pressure alleviating means for alleviating sudden fluctuations in the air pressure applied to the displacement means by the air pressure of the tire.
The tire air pressure detection device according to , 3 or 4. (6) Claims 1, 2, 3, and 4 further comprising a blocking means for blocking the air in the tire and the air acting on the displacement means when the air pressure in the tire exceeds a reference value.
, or the tire air pressure detection device according to 5. (7) The tire air pressure detection device according to claim 1, 2, 3, 4, 5, or 6, wherein the reciprocating direction is perpendicular to the direction of centrifugal force of the tire.