JP2592229Y2 - Variable tire pressure device - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for varying the air pressure of a tire, and more particularly to a technique for appropriately adjusting the air pressure.

[0002]

2. Description of the Related Art FIG. 6 shows a conventional automatic tire pressure adjusting device for an automobile (see Japanese Utility Model Application Laid-Open No. 63-163).
JP-A-151304, Japanese Utility Model Laid-Open No. 1-42904 and Japanese Utility Model Laid-Open No. 1-47022). That is, in this figure, a shaft portion 1B protruding from an end face of a main body portion 1A of a rotating wheel mounting portion 1 is rotatably supported by a center hole 2a of a fixed annular rotary joint 2. An air passage 3 communicating with the tire is formed in the main body 1A and the shaft 1B. The rotary joint 2 and the shaft portion 1B of the wheel mounting portion 1 are provided with an air supply passage portion 4 communicating with an air pressure control circuit in which an air tank, a pressure control valve, and the like (not shown) are provided.

[0003] The air from the air pressure control circuit is supplied to the tire via the air supply passage 4 and the air passage 3.

[0004]

However, such a conventional automatic tire pressure adjusting device has the following problems. That is, although the rotary sliding surface between the rotary joint 2 and the shaft portion 1B of the wheel mounting portion 1 is sealed by the air seal 5, air pressure is always applied to the seal portion. Tire pressure drops when parked or stopped.

[0005] For this reason, if the tire pressure is to be maintained at a specified value even when the vehicle is parked or stopped, it is necessary to always operate the automatic tire pressure adjusting device, and there is a problem that the air consumption increases. In addition, damage to the rotary joint 2 and wear of the seal are likely to occur. Conventionally, as a device for automatically adjusting tire air, Japanese Patent Publication No. 4-1904
There is one disclosed in Japanese Patent Application Laid-open No. 2 (1994). Japanese Patent Publication No. 4-38955 discloses an air supply device for supplying control air to an air-operated device from an outer circumferential direction of a rotating shaft through an air passage.

Accordingly, the present invention has been made in view of the above, and an object of the present invention is to perform appropriate tire pressure variation with a minimum amount of air consumption without being affected by air leakage from a rotary joint.

[0007]

According to the present invention, a shaft protruding from an end surface of a rotating wheel mounting portion is freely rotatable in a center hole of a non-rotating annular rotary joint, and the rotary joint is free from rotation. The main body portion and the shaft portion of the wheel mounting portion are supported so as to be slidable by a predetermined amount, and an air passage portion that communicates with a tire is formed, and the rotary joint and the shaft portion communicate with an air pressure control circuit. Forming an air supply passage portion, communicating the air passage portion with the air supply passage portion, and interposing a check valve downstream of a communication portion of the air passage portion with the air supply passage portion; A return spring is provided which constantly urges the joint in a direction away from the end face side of the main body portion of the wheel mounting portion, and the rotary joint opposes the elastic force of the return spring. A sliding means for slidably moving in a direction approaching the main body end face side, and a normally closed release valve which is pressed by the rotary joint to release the air passage when the rotary joint slides; It is configured to be provided on the end face side.

[0008]

In this configuration, no pressure is applied to the rotary joint except when the tire air pressure is changed.
Tire pressure drop, damage to the rotary joint, seal wear, etc. can be prevented.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 2 shows a rotating wheel mounting portion 11 and the wheel mounting portion 1.
FIG. 2 is a cross-sectional view showing a structure of a non-rotary rotary joint 12 that supports the rotary joint 1. The wheel mounting portion 11 includes a main body 11A and a shaft 11B protruding from an end surface of the main body 11A, and is made of a magnetic material such as a metal.

The rotary joint 12 is formed in an annular shape having a central hole 12a penetrated therein. In this central hole 12a, a shaft portion 11B of the wheel mounting portion 11 is rotatable and a predetermined amount of the rotary joint 12 is provided. Fitted and supported to be slidable. In this case, the end of the shaft 11B protrudes from the center hole 12a, and the washer 13 and the snap ring 14 are fitted around the projected end.

An annular projecting portion 11a is formed on the outer periphery of the end of the main body 11A on the rotary joint 12 side, and is formed between the inner peripheral surface of the projecting portion 11a and the outer peripheral surface of the end of the rotary joint 12. Is provided with an air seal 15. The air seal 15 is a rubber lip-type seal having a lip portion 15a as shown in FIG. 2, and its operation will be described later.

An air seal 16 such as an O-ring is interposed between the outer peripheral surface of the shaft portion 11B and the inner peripheral surface of the center hole 12a of the rotary joint 12. The wheel mounting part 11
An air passage communicating with the tire is formed in the main body 11A and the shaft 11B. In this case, the hole 17A extending from the outer peripheral surface of the main body 11A to the center of the main body 11A and the main body 1 extending in the axial direction from the center of the end face of the shaft 11B.
A hole 17B communicating with the hole 17A on the 1A side is formed, and the holes 17A and 17B constitute the air passage portion. An air hose 18 connected to the tire is connected to the opening end of the outer surface of the main body 11A of the hole 17A. An opening end of the hole 17B at the center of the end face of the shaft 11B is closed by the plug 19.

The rotary joint 12 and the shaft 1
An air supply passage is formed in 1B. In this case, a hole 20A extending from the outer peripheral surface of the rotary joint 12 to the inner peripheral surface of the center hole 12a, an annular groove 20B formed along the inner peripheral surface of the center hole 12a, and a hole 2A formed on the outer peripheral surface of the shaft portion 11B.
A hole 20C extending from the position communicating with 0A to the hole 17B.
Are formed, and these holes 20A and 20C and the annular groove 2 are formed.
0B constitutes the air supply passage. The hole 2
An air hose 21 connected to an air pressure control circuit, which will be described later,
Is connected.

A check valve (check valve) that allows only air flow from the hole 20C to the hole 17B is provided downstream of the communicating portion of the hole 17B forming the air passage portion with the hole 20C forming the air supply passage portion. 22 is interposed. Here, the rotary joint 12 is connected to the main body 11A of the wheel mounting portion 11.
There is provided a return spring 23 which is constantly biased in a direction away from the end face side.

That is, the main body 1 of the rotary joint 12
An annular recessed portion 12b is formed around the shaft portion 11B at the end opposite to 1A, and the return spring 23 is disposed inside the recessed portion 12b. A plurality of stoppers 24 that can come into contact with the end surface of the main body 11A are formed at a plurality of positions around the recess 12b at the end of the rotary joint 12 facing the main body 11A. Further, a thrust bearing 25 is provided inside the recess 12b to receive the movement of the rotary joint 12 in the thrust direction, that is, the movement at the time of sliding movement.

Further, a slide means is provided for sliding the rotary joint 12 in a direction approaching the end face side of the main body 11A of the wheel mounting portion 11 against the elastic force of the return spring 23. This sliding means is constituted by a solenoid having the rotary joint 12 as a movable body.

That is, the main body 1 of the rotary joint 12
An exciting coil 26 is fitted around the stopper 24 at the end facing 1A. Here, by forming the rotary joint 12 from a magnetic material such as a metal, the rotary joint 12 is magnetized by energizing the excitation coil 26 to become an electromagnet, and the rotary joint 12 is formed of the metal wheel mounting portion 11. It is magnetically attracted to the end face side of the main body 11A and slides. The excitation coil 26 receives a control signal from a control unit described later via a harness 27.

A normally closed release valve 28 which is pressed by the rotary joint 12 to release the air passage when the rotary joint 12 slides.
Is provided. That is, a communication hole 29 extending from the vicinity of the shaft portion 11B on the end face of the main body portion 11A on the rotary joint 12 side to the hole 17A is formed.
9 is provided with a release valve 28. This release valve 28
As shown in the figure, the valve body 28a, the valve seat 28b and the valve body 28a
And a spring 28c that elastically biases the valve body 28a in a direction of contact with the valve seat 28b.
Protruding toward the side end face.

Accordingly, when the rotary joint 12 slides, the thrust bearing 25 of the rotary joint 12 presses the operating portion 28d of the release valve 28 to release the valve body 28a against the elastic force of the spring 28c. It is made to let. Next, the configuration of the air pressure control circuit will be described with reference to FIG.

That is, the air circuit from the air compressor 30 to the air hose 21 connected to the air supply passage of the rotary joint 12 has an air reservoir 31, a pressure regulating valve 32 for setting the circuit pressure to a predetermined value, and a circuit pressure. A pressure sensor 33 for detecting, a flow rate sensor 34 for measuring a flow rate of the circuit, and a pressure increasing valve 35 for increasing the pressure of the circuit are provided respectively.

The target value setting signal of the pressure regulating valve 32, the circuit pressure detection signal and the flow rate detection signal output from the pressure sensor 33 and the flow rate sensor 34, respectively, are input to the control unit 36. Also, this control unit 3
From 6, the excitation coil of the solenoid 35 a that operates the booster valve 35 based on the signal for controlling the pressure regulating valve 32 and the circuit pressure detection signal and the flow rate detection signal so that the circuit pressure becomes the target value. A signal for controlling the excitation coil 26 of the solenoid (the rotary joint 12 is a movable body) for operating the release valve 35b and the release valve 28 is output.

In FIG. 4, a portion A (a portion of the tire 37, the check valve 22, and the release valve 28) surrounded by a dotted line is a portion that rotates integrally with the tire 37. The operation of the air pressure control circuit having such a configuration will be described with reference to the flowchart of FIG. In the flowchart, step 1 (in the figure,
Abbreviated as S1. In the following, the pressure regulating valve 32 is set to the target value based on the output signal from the control unit 36. In step 2, the pressure increasing valve 35 is opened, and in step 3, the timer is operated to allow a predetermined time to elapse, and wait for the pressure to stabilize. In step 4, based on the flow rate detection signal output from the flow rate sensor 34, it is determined whether or not air is being supplied to the circuit. If the air is not being supplied, proceed to step 5 to shift to the decompression process,
The pressure increasing valve 35 is closed, the process proceeds to step 6, the release valve 28 is released for a predetermined time, and the process returns to step 2 to open the pressure increasing valve 35. On the other hand, if it is determined in step 4 that the air is being supplied, the process proceeds to step 7 in order to shift to the pressure increasing process, and it is determined whether or not the pressure of the circuit is the target value. If not, the process returns to step 7 and repeats this determination. If the pressure is the target value, the process proceeds to step 8, closes the pressure increasing valve 35, and returns to the step.

In the structure shown in FIG.
Prevents the intrusion of dust and dirt from the outside, but the release valve 28 is opened by the above operation, and the air passage portion (hole 17) is opened.
A, 17B), the air escapes and the internal pressure of the space B between the main body 11A and the rotary joint 12 increases, so that the lip 15a is deformed and the seal of the space B is released, and the space B is released. Acts to let air escape from the outside.

According to this configuration, the tire pressure is increased or reduced by the air pressure control circuit so as to become the target value, and the tire pressure can be set to an appropriate value. A check valve 22 that allows only the air flow from the hole 20C to the hole 17B is provided downstream of the communication portion between the hole 17B that forms the air passage portion and the hole 20C that forms the air supply passage portion. Therefore, except when air is supplied to the tire, no pressure is applied to the seal portion of the rotary joint 12, air leakage is small, and the tire air pressure does not drop during parking and stopping for a short time. Therefore, even if the tire pressure is to be maintained at the specified value even when the vehicle is parked or stopped, it is not necessary to always operate the tire pressure control circuit, and the air consumption can be reduced.

Further, damage to the rotary joint 12 and abrasion of the seal hardly occur. As described above, the present invention has been described with reference to the specific embodiments. However, the present invention is not limited to the embodiments, and may be implemented by a person skilled in the technical field attached to the present invention. It should be noted that various changes and modifications can be made without departing from the scope of the claims.

[0026]

As described above, according to the present invention, the pressure is not applied to the rotary joint except when the tire air pressure is changed, so that a decrease in tire air pressure, damage to the rotary joint, seal wear, etc. can be prevented. This has a great practical effect that an appropriate tire pressure can be varied with a minimum amount of air consumption without being affected by air leakage from a joint.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of an embodiment of a tire air pressure varying device according to the present invention.

FIG. 2 is a partially enlarged sectional view of the embodiment.

FIG. 3 is a partially enlarged sectional view of the embodiment.

FIG. 4 is a diagram showing a tire pressure control circuit in the embodiment.

FIG. 5 is a flowchart illustrating control contents of a tire pressure control circuit according to the first embodiment;

FIG. 6 is a sectional view showing a conventional automatic tire pressure adjusting device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Wheel attachment part 11A Body part 11B Shaft part 12 Rotary joint 12a Center hole 17A hole 17B hole 20A hole 20B Annular groove 20C hole 22 Check valve 23 Return spring 26 Excitation coil 28 Release valve

Claims (1)

(57) [Scope of request for utility model registration] 1. A shaft protruding from an end surface of a main body portion of a rotating wheel mounting portion is supported in a center hole of a non-rotating annular rotary joint so that the rotary joint can freely rotate and slide by a predetermined amount, The main body portion and the shaft portion of the wheel mounting portion form an air passage portion that communicates with a tire, and the rotary joint and the shaft portion form an air supply passage portion that communicates with an air pressure control circuit. Section and the air supply passage section, and a check valve is interposed on the downstream side of the communication section of the air passage section with the air supply passage section, while the rotary joint is connected from the end face side of the main body section of the wheel mounting section. A return spring that constantly urges in a direction away from the wheel is provided, and the rotary joint slides in a direction approaching the end surface of the main body portion of the wheel mounting portion against the elastic force of the return spring. Providing slide means for moving,
An air pressure varying device for a tire, characterized in that a normally closed release valve, which is pressed by the rotary joint when the rotary joint slides to release the air passage portion, is provided on an end surface side of the main body portion of the wheel mounting portion.