JP2011131705A - Air suspension device with piezoelectric conversion function of vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an air suspension device with the piezoelectric conversion function of a vehicle, which can secure electric power usable for on-vehicle electric equipment from large vibration energy when absorbing a shock of an air spring. <P>SOLUTION: There is provided a piezoelectric element 30 for generating AC electric power by the piezoelectric effect generated when absorbing a shock of road surface vibration, inside the air spring 15 for an air suspension interposed between a chassis frame 1 and an axle 14, and the electric power generated by the piezoelectric element 30 is supplied to a storage battery 40 being a power supply of the electric equipment mounted on the vehicle. With this constitution, the large vibrational energy when absorbing the shock of the air spring 15 disposed of so far, is converted into the electric power by the piezoelectric element 30, and is stored in the storage battery 40, and the electric power stored in the storage battery 40 is used for the on-vehicle electric equipment 6. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an air suspension device with a piezoelectric conversion function for a vehicle that can generate electric power from the behavior of an air spring when absorbing a shock of road surface vibration.

An electric vehicle using a motor as a power source and a hybrid electric vehicle (vehicle) using an engine and a motor as power sources travel using electric power stored in a storage battery mounted on the vehicle. Such an electric vehicle has a problem that the travel distance cannot be obtained because the capacity of the storage battery is limited.
Therefore, recently, the storage energy can be stored using technology that converts regenerative energy during braking into electric power and charges the battery, or technology that converts engine exhaust heat energy into electric power by Rankine cycle and charges the battery. Electric power is also used to operate electric devices such as motors.

Even this is not enough. For this reason, in electric vehicles and hybrid electric vehicles, studies are also being made on the recovery of energy generated from others. Then, focusing on the vibration of the car, it has begun to consider collecting vibration energy as electric power.
For this purpose, attention is paid to the vibration of the engine as disclosed in Patent Document 1, and it is considered that electric power is obtained from the vibration of the engine using a piezoelectric element.

Japanese Patent Laid-Open No. 2005-137881

However, the piezoelectric element has a feature that a surface charge proportional to the pressure appears. Even at the pressure of the degree of engine vibration, even if the electric power for generating heat from the heater is ensured as in the cited document 1, the electric power is large. It is far from securing.
For this reason, the vibration energy of automobiles is not effectively utilized at present, and a technique for effectively securing electric power from vibration energy using a piezoelectric element is desired.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an air suspension device with a piezoelectric conversion function for a vehicle that can secure electric power that can be used for in-vehicle electric equipment from a large vibration energy at the time of shock absorption by an air spring.

In order to achieve the above object, the invention according to claim 1 is characterized in that an AC power is generated by a piezoelectric effect generated when a shock of road surface vibration is absorbed in an air spring for air suspension interposed between a chassis frame and an axle. The piezoelectric element which generate | occur | produces was provided, and it was set as the structure which supplies the electric power which generate | occur | produced with this piezoelectric element to the storage battery used as the motive power source of the electric equipment mounted in a vehicle.
According to this configuration, large vibration energy at the time of shock absorption of the air spring that has been discarded so far is converted into electric power by the piezoelectric element and stored in the storage battery. The electric power stored in this storage battery becomes the electric power used for the on-vehicle electric device.

The invention of claim 2 further includes a rectifier connected to the piezoelectric element and the storage battery, rectifying AC power generated by the piezoelectric element into DC power, and storing the DC power in the storage battery.
In the invention of claim 3, the air spring has a cylindrical shape interposed between the plate member fixed to the chassis frame and the piston fixed to the axle so that the wiring structure for connecting the rectifying unit and the storage battery can be simplified. In addition to the configuration having a diaphragm, the piezoelectric element is supported by a plate member that is not displaced by road surface vibration.
According to a fourth aspect of the present invention, the piezoelectric element is composed of a columnar element so that a larger electric power is generated, and an input portion that receives pressure on the distal end side of the piezoelectric element can be projected from the plate member and protruded into the diaphragm. Adopted structure.

According to the invention of claim 5, the input portion of the piezoelectric element is arranged so as to avoid interference with the bump stopper so that the piezoelectric element can be attached without being affected by the bump stopper.
According to the sixth aspect of the present invention, in order to reliably avoid interference between the input portion of the piezoelectric element and the bump stopper, the input portion of the piezoelectric element is from a point of the plate member corresponding to the hole portion of the protruding end portion of the bump stopper. The inside of the diaphragm is projected so that the outer shape of the input portion is allowed to be accepted by the hole of the bump stopper.

  According to the seventh aspect of the present invention, the outer diameter of the input portion of the piezoelectric element is smaller than the diameter size of the hole portion of the bump stopper, and the diaphragm of the input portion has an outer shape that is maximum in the input portion so that interference can be prevented easily. The length dimension protruding inside was set shorter than the length dimension of the hole of the bump stopper.

According to the first aspect of the present invention, it is possible to secure electric power that can be used for the electrical equipment of the vehicle from the large vibration energy at the time of shock absorption of the air spring that has been discarded until now, using the piezoelectric effect of the piezoelectric element. .
According to invention of Claim 2, the direct-current power which rectified the alternating current power generated with the piezoelectric element can be stored in a storage battery.
According to the invention of claim 3, since the piezoelectric element is supported by the plate member on the chassis frame side that does not displace, not on the axle side that displaces following the wheel, the wiring that interacts with the piezoelectric element and the rectifying unit, storage battery, etc. The structure is simple.

According to the invention of claim 4, it is possible to generate a large power output by assembling the columnar piezoelectric element.
According to the invention of claim 5, the piezoelectric element can be attached to the plate member without being affected by the bump stopper.
According to the invention of claim 6, interference between the piezoelectric element and the bump stopper can be reliably prevented with an easy structure.
According to the seventh aspect of the present invention, interference between the piezoelectric element and the bump stopper can be easily prevented only by setting the outer shape of the piezoelectric element.

The perspective view which shows the air suspension apparatus with a piezoelectric conversion function of the 1st Embodiment of this invention. Sectional drawing which shows the attachment structure of the piezoelectric element in the apparatus with the circuit around the piezoelectric element. Sectional drawing which shows the principal part of the 2nd Embodiment of this invention.

Hereinafter, the present invention will be described based on the first embodiment shown in FIG. 1 and FIG.
FIG. 1 shows an air suspension installed in a vehicle, for example, a suspension device 10 installed in a hybrid electric truck of a large vehicle such as a truck or a bus. Here, a front-side air suspension device 10 (only one side is shown) is shown. FIG. 2 shows an air spring structure of the air suspension device 10.

  First, the outline of the vehicle structure will be described with reference to FIG. 1. In FIG. 1, reference numeral 1 denotes a chassis frame, for example, a plurality of cross members between a pair of side frames 2 (only one side is shown) extending in the vehicle front-rear direction. It has a ladder shape (not shown). On the front side of the chassis frame 1, an engine 3, a traveling motor 4, a transmission 5, a cab (not shown), a pair of front wheels 6 (corresponding to wheels of the present application), and the like are provided. On the rear side of the chassis frame 1 are provided a differential (not shown) that receives power from the engine 3 and the traveling motor 4, and a pair of rear wheels (not shown) that are driven by the driving force distributed from the differential. It is done. In addition, the chassis frame 2 is provided with a storage battery 40 serving as a power source for electric devices mounted on the vehicle such as the traveling motor 4 and other air-conditioning devices and lighting devices.

  A front wheel 6 and a rear wheel (not shown) are respectively suspended on both sides in the vehicle width direction of the chassis frame 1 by using an air suspension device 10 (FIG. 1 shows only the front wheel 6 side). The air suspension device 10 for the front wheel 6 has a structure that absorbs shock caused by road surface vibrations, for example, an axle 14 that is disposed immediately below the chassis frame 1 so as to intersect the chassis frame 1, and the axle 14 and the side An absorption structure including an air spring 15 and a shock absorber 16 interposed between the frame 2 and the frame 2 is used. As a structure for maintaining the posture, a link structure composed of various rod members, for example, a radius rod 7 is used, and the air suspension device 10 is composed of a combination of both. The front wheels 6 are attached to both end portions of the axle 14. Although not shown, the same structure is used for the air suspension device on the rear wheel side.

  As shown in FIG. 2, the air spring 15 includes a pair of disk-like upper plates 20 (corresponding to the plate member of the present application) attached to the side frame 2 and a short cylindrical piston attached to the axle 14. 21 and a cylindrical diaphragm 22 interposed between the upper plate member 20 and the piston 21 are used. The diaphragm 22 is filled with air of a predetermined air pressure from an air tube connector 23 provided on the upper plate 20. The upper plate 20 is fixed to the lower part of the side frame 2 via the chassis side bracket 25, the lower part of the piston 21 is fixed to the upper part of the front axle 14, and the shock of road surface vibration transmitted from the front wheel 3 is applied to the diaphragm 22. It is structured to be absorbed by expansion / contraction (deformation).

  A bump stopper 27 is provided on the top of the piston 21. The bump stopper 27 has, for example, a truncated cone-shaped buffer portion 27 a that protrudes into the diaphragm 22. As a result, even if the diaphragm 22 is deformed in the direction of contracting to the limit region, interference between the piston 21 and the upper plate 20 can be avoided by the restriction by the buffer portion 27a. In addition, the hole part 27b for ensuring buffer performance is formed in the center of the front end surface of the buffer part 27a.

  Each air suspension device 10 is provided with a piezoelectric conversion function for converting road surface vibration into electric power. This function converts energy at the time of shock absorption into electric power. The piezoelectric conversion structure that provides the same function is the same as the air suspension device 10 for the front and rear wheels. FIG. 2 shows the piezoelectric conversion structure of the air suspension device 10 for the front wheel 6.

  The same structure will be described. For the piezoelectric element 30, for example, a columnar element is used in order to enhance the piezoelectric effect. For example, a stacked piezoelectric element 30 that can secure a large electric power by stacking a large number of piezoelectric bodies and connecting them in series is used. The piezoelectric element 30 serves as an input portion that receives pressure from the conical tip portion 30a. The piezoelectric element 30 is attached inside the air spring 15. The piezoelectric element 30 is attached not to the axle 14 side that moves up and down following the front wheel 6 (wheel) but to the upper plate 20 on the chassis frame 1 side that does not move.

  That is, the piezoelectric element 30 is fixed to a pair of upper plates 20 that sandwich the opening end of the diaphragm 22, and the tip end 30 a protrudes into the inside of the diaphragm. Specifically, the main body portion 30 b of the piezoelectric element 30 is fixed so as to pass through the central portion of the upper plate 20 corresponding to the position of the hole portion 27 b of the bump stopper 27, and the tip end portion 30 a forming the input portion is separated from the plate 20. It protrudes to the opposite piston 21 side and protrudes into the diaphragm. For fixing the main body portion 30b, for example, a structure is used in which a set of nuts 32 is used to fasten the diaphragm 14 to the upper plate 20 while keeping the sealed state of the diaphragm 14. By arranging the piezoelectric element 30 at a point corresponding to the hole 27, interference from the bump stopper 27 is avoided. The pair of upper plates 20 are fastened with bolts and nuts 26.

  As a result, the piezoelectric element 30 generates electric power due to the piezoelectric effect when the distal end portion 30a receives the pressure of the internal air of the diaphragm 14 generated when absorbing the shock of the road surface vibration. Since the road surface vibration transmitted to the diaphragm 14 repeats up and down, AC power is continuously generated from the piezoelectric element 30. The inherent frequency of the piezoelectric element 30 is a frequency (Hz) band of road noise brought about by a general road surface input so that it matches the vibration frequency band at the time of steady running of the vehicle. An appropriate frequency is selected and set in consideration of vehicles such as passenger cars, trucks, buses, etc., which differ depending on the vehicle type, weight, driving condition, etc., and the piezoelectric effect is effective by vibration from the road surface. Is to be demonstrated. In addition, the frequency band of the road noise of “around 100 Hz to around 1000 Hz” is based on “Automotive Technology Handbook 1 Basic and Theoretical P325 FIG. 8-1” issued by the Japan Society for Automotive Engineers.

  Further, the outer shape of the tip portion 30a of the piezoelectric element 30 is set to a size allowed by the hole portion 27b of the buffer portion 27b, and even if the bump stopper 27 rises to the limit region, the tip portion 30a remains on the bump stopper 27. The buffer portion 27a is not buffered. Specifically, in the piezoelectric element 30, the diameter d of the nut 32 that is the largest diameter of the tip 30 a protruding into the diaphragm is smaller than the diameter D of the hole 27 b of the bump stopper 27, and the tip 30 a. The length dimension h protruding into the diaphragm is determined to be shorter than the length dimension H of the hole 27b of the bump stopper 27, so that interference with the bump stopper 27 can be reliably prevented.

  The piezoelectric element 30 is connected to a rectifying unit 35 provided on the chassis frame 1 side (vehicle body side). For example, as shown in FIG. 2, the rectifier 35 uses a full-wave rectifier circuit configured by a combination of four diodes 36 a to 36 d and a capacitor 37, and rectifies AC power generated by the piezoelectric element 25 into DC power. I can do it. The rectifying unit 35 is connected to the storage battery 40 so that the rectified DC power is stored in the storage battery 40.

With such an air suspension device 10, electric power that can be used for in-vehicle electric equipment is secured from the input vibration energy.
In other words, during running of the vehicle, road surface irregularities become road surface vibrations and are transmitted from the front wheels 6 and the rear wheels (not shown) to the air springs 15 and shock absorbers 16 of the air suspension devices 10. At this time, each air spring 15 and each shock absorber 16 are expanded and contracted by road surface vibration to absorb the shock.

  Specifically, when the air spring 15 gets over the road joints and the vibration in the direction of pushing up from the front wheel 6 or the rear wheel is applied, the filled internal air is pushed by the piston 21 that is displaced upward, and the pushing up is not performed. When it disappears, the piston 21 repeats the behavior of returning (or vice versa) and absorbs the shock of road surface vibration.

  Each time the vibration shock is absorbed, the tip 30a of the piezoelectric element 30 is repeatedly compressed by the internal air of the air spring 15 pushed by the piston 21 as indicated by the arrow a in FIG. Due to the effect, AC power is continuously generated from the piezoelectric element 30. At this time, since the vibration energy transmitted to the air spring 15 is much larger than the engine vibration, a considerable amount of electric power is continuously generated while the vehicle is running. Thus, the vibration energy at the time of shock absorption of the air spring 15 is converted into electric energy (piezoelectric element power generation). The output AC power is converted into DC power by the rectifying unit 35 and stored in the storage battery 40 sequentially.

  Therefore, the vibration energy at the time of shock absorption of the air suspension device 10 that has been discarded so far can be used as electric power that can be used for electric devices such as the traveling motor 4. In particular, since the piezoelectric element 30 is disposed inside the air spring, a large amount of electric power can be expected because a large amount of energy generated when absorbing the shock of the air spring 15 is used as it is to generate electric power. In addition, the piezoelectric element 30 is set to the natural frequency that matches the vibration frequency range during steady running of the vehicle, among the frequency bands of “around 100 Hz to around 1000 Hz” of road surface vibration, so that the most during the running of the vehicle. Electric power can be output effectively. The power generation by the piezoelectric element 30 is effective for a heavy vehicle with a heavy weight that easily generates a large shock.

  Further, since the piezoelectric element 30 is supported by the upper plate 20 on the side of the chassis frame 1 that is not displaced, rather than the axle 14 that moves up and down following the wheel, the rectifying unit 35 and the storage battery 40 can be easily engaged with each other. The wiring structure for engaging the storage battery 40 is simple. In addition, by assembling the columnar piezoelectric element 30 that easily generates large electric power, the electric power can be recovered from the piezoelectric element 30 more effectively.

  Further, since the piezoelectric element 30 is arranged so as to avoid the bump stopper 27, the influence of interference with the bump stopper 27 can be suppressed. In addition, the tip portion 30a of the piezoelectric element 30 is not only disposed directly above the hole portion 27a of the bump stopper 27 but also has an outer shape allowed by the hole portion 27a. Therefore, the tip portion 30a protruding inside the diaphragm and Interference with the buffer portion 27a of the bump stopper 27 can be reliably prevented. In this case, the piezoelectric element 30 has a diameter dimension d of the tip portion 30a protruding into the diaphragm smaller than a diameter dimension D of the hole portion 27b of the bump stopper 27 and a length dimension h protruding into the diaphragm of the tip portion 30a. Since it is only necessary to use an element set shorter than the length dimension H of the hole 27b of the bump stopper 27, it is simple.

Although the output of the piezoelectric element 30 is directly guided to the rectifying unit 35, when the output of the piezoelectric element 30 is desired to be increased, the piezoelectric element 30 and the rectifying unit 35 are connected as shown by the two-dot chain line in FIG. The output from the piezoelectric element 30 may be boosted with a transformer 45 interposed therebetween as a boosting means.
FIG. 3 shows a second embodiment of the present invention.
In the present embodiment, the piezoelectric element 30 is not attached to the upper plate 20 as in the first embodiment, but is attached to the piston 21 on the opposite side.

Specifically, for example, a passage 50 for inserting a piezoelectric element from the lower surface to the upper surface side is provided in the center of the piston 21 (a point corresponding to the hole 27b), and the main body portion of the piezoelectric element 30 is provided at the end of the passage 50. 30 b is fixed, and the tip 30 a of the piezoelectric element 30 is projected from the upper surface of the piston 21 into the hole 27 b of the bump stopper 27. Even in this case, similarly to the first embodiment, the piezoelectric element 30 provided inside the air spring is used to effectively generate electric power from the energy at the time of shock absorption without interfering with surrounding objects. Can do.
However, in FIG. 3, the same parts as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  Note that the present invention is not limited to the above-described embodiment, and various modifications may be made without departing from the spirit of the present invention. For example, in the above-described embodiment, an example in which a columnar piezoelectric element is used has been described. However, the present invention is not limited to this. Alternatively, the plate-shaped piezoelectric element may be attached to the inner surface of the air spring including the diaphragm 22 to output electric power. Further, although the tip 30a of the columnar piezoelectric element 30 protrudes from the upper plate 20 toward the piston 21 and protrudes into the diaphragm 22, it may be flush with the upper plate 20. In the above-described embodiment, the present invention is applied to a vehicle that uses an engine and a motor as a power source. However, the present invention is not limited to this, and may be applied to a vehicle that uses a motor as a power source and other vehicles.

1 Chassis frame 6 Front wheel
10 Air Suspension Device 14 Axle 15 Air Spring 20 Upper Plate (Plate Member)
21 Piston 22 Diaphragm 27 Bump stopper 27b Hole 30 Piezoelectric element 30a Tip (input part)
35 Rectifier 45 Storage battery

Claims (7)

The chassis frame of the vehicle,
An axle that supports the wheels of the vehicle;
An air spring for suspension that is provided between the chassis frame and the axle and absorbs road surface vibration transmitted from the wheels;
A storage battery serving as a power source for the electrical equipment mounted on the vehicle;
A piezoelectric element which is provided inside the air spring and generates electric power by a piezoelectric effect generated when absorbing a shock of road surface vibration;
An air suspension device with a piezoelectric conversion function for a vehicle, characterized in that the electric power generated by the piezoelectric element is supplied to the storage battery.   The rectifying unit connected to the piezoelectric element and the storage battery, rectifies AC power generated by the piezoelectric element into DC power, and stores the DC power in the storage battery. Air suspension device with piezoelectric conversion function for vehicles. The air spring is
A plate member fixed to the chassis frame;
A piston fixed to the axle;
A cylindrical diaphragm that is interposed between the plate member and the piston and can be deformed following the road surface vibration transmitted from the piston;
The air suspension device with a piezoelectric conversion function for a vehicle according to claim 1 or 2, wherein the piezoelectric element is supported by the plate member. The piezoelectric element is composed of a columnar element having an input part that receives pressure on the tip side,
The air suspension device with a piezoelectric conversion function for a vehicle according to claim 3, wherein the input portion protrudes from the plate member toward the piston and protrudes into the diaphragm. The piston side includes a bump stopper protruding into the diaphragm,
The air suspension device with a piezoelectric conversion function for a vehicle according to claim 4, wherein the input portion of the piezoelectric element is disposed so as to avoid interference with the bump stopper. The protruding end face of the bump stopper has a hole,
6. The vehicle piezoelectric device according to claim 5, wherein the input portion of the piezoelectric element is disposed at a point of the plate member corresponding to the hole portion, and has an outer shape that is allowed by the hole portion. Air suspension device with conversion function. The outer diameter of the input part of the piezoelectric element is such that the maximum diameter dimension in the input part is smaller than the diameter dimension of the hole part of the bump stopper, and the length dimension protruding into the diaphragm of the input part is The air suspension device with a piezoelectric conversion function according to claim 6, wherein the air suspension device is set to be shorter than the length of the hole.

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