JPH01257750A - Heating element having ptc wafer for vessel - Google Patents

Abstract

PURPOSE: To heat the sucked fuel steam and to rapidly release it by installing a wafer made of electrothermal material in air inlet of a fuel steam recovery container. CONSTITUTION: A heating element 16 is arranged in a container 10 that contains absorbent carbon 15 therein for sucking and releasing fuel steam. The heating element 16 made of wafer 18 of PTC ceramics is installed in the heating element casing 20. An inlet 28 is formed in the bottom wall 26 of the heating element casing 20, and a suction regulating disc 40 composed of circuit plate is pressed in. While fuel steam is released, the air passes through the suction passageway 52, an inlet 28 formed in the bottom wall 26 and a hole 41 formed in the suction regulating disc 40, and last is sucked into the chamber formed by the suction regulating disc and the wafer 18. Therefore, the air is uniformly heated by the wafer 18.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an automotive vehicle containing an absorbent material that captures and stores fuel vapor from the fuel tank and carburetor and releases it during operation of the vehicle. Relating to a fuel vapor recovery vessel.

BACKGROUND OF THE INVENTION Various attempts have been made to limit the escape of gasoline vapors from automobiles into the atmosphere, particularly gasoline vapors produced during idle operation. Special fuel tank caps were used to reduce or eliminate vapors from the fuel tank. Others included a carbon-filled container connected to the fuel tank to absorb and condense fuel vapor. Connection to the fuel tank is made at the inlet port of the carbon-filled vessel. The second or discharge port of this type of container is connected to the engine's intake manifold or carburetor. When the engine starts, the condensed fuel and vapor stored in the carbon
Once released, it is sucked into the engine and burned.

Both open-bottom and open-bottom containers have been proposed. Open-bottom containers typically have one or more large air intake passages to admit outside air from the engine section during engine operation. This inflow of outside air into the vessel picks up the stored fuel from the carbon and carries it to the carburetor or suction manifold. Steam subsequently entering the vessel during engine operation is continuously vented to keep the carbon "dry" and ready to absorb steam after the engine has shut down. A fibrous filter material is used at the outside air intake to prevent dirt and dust from entering the container.

Some vessels draw vapor from both the fuel tank and the float chamber of the carburetor when the engine is stopped and release it while the engine is running, while others recover vapor only from the fuel tank.

If it is desired to draw vapor from both the fuel tank and the float chamber of the carburetor, a control valve can be used to vent the float chamber into a container when the engine is not running, without interfering with normal operation of the engine. That's how it is. Some engines also incorporate a plurality of pressure valves for the fuel tank to limit exhaust from the fuel tank during idle operation and to increase exhaust to the container during engine operation.

A problem with activated absorbent materials contained in vapor vessels is that low temperatures make it difficult for the fuel to release. Many absorbers release stored fuel well at room temperature, but
Efficiency decreases at lower temperatures.

For this reason, a container unit of this type is installed in the engine part of a motor vehicle in order to ultimately obtain the desired high temperature. Initially, the fuel within the container tends to stay there and not be immediately withdrawn.

U.S. Patent Nos. 3,221,724 and 3,757
No. 753 shows a container of this type which is heated directly by the engine. In U.S. Pat. No. 3,221,724, a container is placed in an automobile air-strainer and heated by air from the engine.

No. 3,757,753, heat is obtained from a jacket placed around the exhaust pipe from the engine. The top of the container is connected to the carburetor's air purifier. Both of these devices rely on heat from the engine.

U.S. Patent Nos. 3,191,587 and 3,675
No. 634 discloses a vapor recovery vessel connected to receive and store vapor from a motor vehicle fuel tank.

U.S. Pat. No. 3,927,300 shows another use of PTc ceramic materials as self-regulating heating elements.

U.S. Patent Section 4108125, No. 42792
No. 34, No. 4387!190, No. 4448173 and No. 4450823 show PTC materials for heating fuel entering the carburetor brake.

In many vapor recovery vessels, the release of vapor is too slow. In cold weather, the initial engine temperature is too low. The jacket around the exhaust pipe does not provide enough transfer heat.

Unexamined Japanese Patent Publication No. 1983-1986, released on October 8th, 1937.
No. 226,554 discloses a mechanism for heating air within a container using a self-regulating PTC ceramic heating element. Each slab uses a zinc die-cast acid grid to improve heat transfer. In addition, a single PTC with a honeycomb structure
A heating element is also disclosed. Although these conventional devices have sufficient performance, the present invention is intended to simplify and modify them in order to reduce the cost while maintaining efficiency.

PROBLEM SOLVED BY THE INVENTION The shortcomings of conventional carbon containment vessels are overcome by the present invention, which provides an improved charcoal-type pollution control device that is simple, reliable, and significantly reduces the release of vapor to the outside atmosphere over a wide temperature range. Solved by invention.

It is also an object of the present invention that heat transfer from a single flat PTC element is carried out along an air flow path passing through heating chambers provided on both sides of the element, and that heat is generated on both sides of the PTC element itself. It is an object of the present invention to provide an improved contamination control device as described above, in which heat transfer to the air is significantly improved due to the increased contact between the surfaces and the opposing walls of the heating chamber.

It is also an object of the present invention to provide an improved pollution control device as described above, in which heating of the air within the container occurs along an efficient serpentine path.

Furthermore, it is an object of the present invention to provide an improved contamination control device as described above in which the bottom of the container is substantially closed to eliminate water ingress.

A related object of the present invention is to provide the above-described improved pollution control device using only a single, inexpensive and simple flat PTC heating element.

It is a further object of the present invention to provide an improved pollution control system as described above, in which fuel vapor recovery begins upon engine startup, and the fuel vapor is efficiently drawn into the shilling and combusted.

Furthermore, it is an object of the present invention to provide an improved pollution control device as described above, which can be installed in a variety of motor vehicles with no or little modification using simple molded plastic and metal parts. It is in.

Means for Solving the Problems These objectives are achieved by an electrical heating element structure attached to the outside air intake of the fuel vapor recovery vessel. The heating element is a wafer of electrically resistive heating material with electrical connections and spacious sides. There is a first chamber wall on one side of the wafer and a second chamber wall on the other side. These two chambers communicate with each other around the wafer, with air flowing into the first chamber, through one side and around the wafer, and into the second chamber roughly on the opposite side of the wafer. Each time the absorbent material is guided through the container, heat is added to the absorbent material inside the container.

The wafer preferably consists of a ceramic material with a positive temperature coefficient. The initial power of the PTC material is high, resulting in rapid heating, which gradually decreases as the temperature increases.

Extremely efficient heat transfer to the air stream is obtained by the serpentine flow path, allowing high efficiency to be achieved without making the geometry of the PTC material more complex.

Other features will be described later.

EXAMPLE FIG. 2 shows a cylindrical container 10 with a side wall 12 and an inner bottom flange 14. FIG. Container 10 is made of activated carbon or carbon that absorbs vapors collected through a vent line (not shown) extending from the vehicle's fuel tank and releases this vapor to the motor vehicle's carburetor (not shown) after the engine has been started. It has carbon 15. This operation is described in Japanese Patent Laid-Open No. 61-226554 published on October 8, 1985.

According to the present invention, activated carbon 1 is used as a retrofit for current fuel vapor recovery vessels.
A new and improved heating element structure 16 is provided which facilitates the release of stored fuel vapor/condensate for combustion in a motor vehicle engine by increasing the temperature of the heating element 5 . The heating element structure 16 consists of a solid, non-porous wafer 18, which is enclosed by a molded plastic heating element case 2.
It is preferably formed of a positive temperature coefficient (PTC) ceramic material, which is attached to the substrate. Heating element case 2
0 comprises eight upright elastic spring pieces 22 by which the heating element case can be snapped onto the inner bottom flange 14. The heating element case 20 is a wafer 18
The base 21 has an upright annular flange 24 surrounding and supporting the base 21 and a bottom wall 26. An intake port 28 is formed in the bottom wall 26 of the heating element case.

On both sides of the wafer 18 are the leads @34. shown in FIG.
An annular terminal 30 integrally provided with a hoe-shaped protrusion 32 connected to 36 is pressed and provided. A plurality of grooves 38 provided in the bottom plate, which will be described later, allow the lead wires 34.
A gap for 36 is provided.

On the bottom wall 26 of the heating element case 20, there is an air intake adjustment disc body 40 made of an aluminum, copper, or copper-coated circuit board (printed circuit board) whose surface facing the wafer 18 is conductive or coated with a metal. Being pushed. This disc body 40 has a hole 41 formed therein. A corrugated washer 42 is placed on one side between the intake adjustment disk 40 and one of the annular terminals 30, and on the other side is an air vent disk 44 in which a plurality of discharge holes 46 are formed.
and the other annular terminal 30.

A molded plastic stop cap 48 is fitted over the upright annular flange 24. Wafer 18, annular terminal 30, wave washer 42, intake adjustment disc body 4
0 and the deflection disk 44 are held in the position shown in FIG. 2, and the corrugated washer 42 applies a spring pressure to the wafer 18 through the annular terminal, thereby pressing the annular terminal against both sides of the wafer 18. This provides good electrical and thermal contact between the two.

As shown in FIGS. 1, 2 and 6, four connecting passages are formed in the inner surface of the upright annular flange 24,
Provides communication between the lower portion of wafer 18 and the upper portion of wafer 18. The connecting passage 50 is shown slightly exaggerated in FIG.

The heating element case 20 is formed on a separate disk-shaped bottom wall 53, and the air intake provided on the bottom wall 26 of the heating case 20]]2
It has a part that covers a wide groove 52 constituting an intake passage communicating with the air intake passage 8. The air flow is expressed as A=4=t in Figure 6.
This is indicated by the arrow. During the discharge operation of the container, the air
Passing through the intake passage 52 from the engine section, the intake port 28 formed in the bottom wall 26 and the hole 41 formed in the intake adjustment disc body 40
and is drawn into the chamber formed by the intake adjustment disk 40 and the wafer 18. In FIG. 6, this lower chamber is designated by the reference numeral 54. The air hitting the center of the lower surface of the wafer 18 is guided radially outward and
, the lower corrugated washer 42, which is in thermal contact therewith, and the intake conditioning disk 40, which receives heat from the wafer 18 by thermal conduction and radiation. Air is in the lower chamber 54
, it is pulled up through four connecting passages 50 and reaches the upper chamber formed by one side of the wafer 18 and the deflecting disk 44 . In FIG. 6, this upper chamber is designated by the reference numeral 56. The air is then directed somewhat radially inward, again absorbing heat from the wafer 18, top corrugated washer 42, and deflector disc 44. The air then exits through holes 46 in the baffle disk and enters the interior of the container 40. Because of the spacing between the plurality of holes 46, air entering the interior of the container has a diffuse flow pattern, effectively achieving a more uniform heat distribution. Two sets of six holes 46 each having a different diameter are arranged so that the larger circular holes are placed circumferentially between the smaller circular holes. A much more satisfactory effect is obtained than if the central hole were deflected and provided in the disk body 44.

Three walls constituting each of the two intake passages 52 are formed by the bottom plate 53, and the remaining walls of each intake passage 52 are formed by the base 21 of the heating element case 2o.

The bottom plate 53 is attached to the heating element case 20 after the parts are assembled.
It is preferably sonic welded to the base 21 of. The stop cup 48 is also preferably sonic welded to the heating element case 20.

To apply the heating element structure according to the present invention to current containers,
A mounting ring 60 with an inwardly facing flange 62 is added to the bottom of the heating element structure. The shape and dimensions of the inwardly facing flange 62 are similar to the shape and dimensions of the inner bottom flange 14 of the container, so the attachment is similar when using the ring 60.
Current mounting on automobiles may utilize brackets (not shown). Current installations connect the bracket with the inward facing flange 62, whereas if a heating element is not attached to the container 10, the current installation has the bracket pre-mated with the inside bottom flange. Attachment is such that the ring 60 is preferably sonic welded at points around the periphery of the bottom plate 53. Typically, the container shown in FIG. 2 is provided with a bottom grate (not shown) above the interior bottom flange 14 to trap the activated carbon within the container. This grid does not constitute the present invention and is therefore omitted from FIG. 2 for the sake of clarity.

Another embodiment of the invention is shown in FIG. 8, in which parts similar to those of the embodiment shown in FIGS. 1-7 are designated by the same reference numerals. The heating element structure of this embodiment includes a wafer 18, an annular terminal 30, and a wave washer 42. The intake disc may be a metallized circuit board 40a with a metal surface facing the wafer 18.

The baffle disk may be a metallized plate 40a with a plurality of holes 46a similar to the holes in the baffle disk 44. The metal surface of the disk body 44a.

It faces the wafer 18. These plates have a thickness of 5/1000 or 6/1000 inches (approximately 0.0
The thin metal layer (127 cm or 0.01524 cm) warms up rapidly upon initial energization of the wafer. Because the ther-mal masses of metal are small, these metallized circuit boards absorb thermal radiation and reach high temperatures quickly. As metallized circuit boards warm, they radiate and transfer heat to the air passing through the chambers they form. The insulating effect of the fiberglass or phenolic materials that typically constitute metallized circuit boards significantly reduces radiation or conduction by the metal in an outward direction and transfers most of the heat received by the metallization to the airflow flowing through it. You will finally be able to tell.

When this metal coating comes into contact with the corrugated washer,
Improved heat transfer to metallized parts.

The heating element structure according to the present invention provides the following effects. That is, a large number of PTC elements or a PTC element with a special shape such as a honeycomb structure is not required. In the device according to the invention it is sufficient to use only one flat plate of a single thickness.

The tortuous route taken by the air flow, indicated by the arrows labeled A in FIGS. 6 and 7, provides a highly effective transfer of heat from the wafer 18. The wafer 18 is in thermal contact with the corrugated washer 42, the air intake conditioning disc 40, and the deflection disc 44.

To this end, two circular chambers 54 and 56 are formed, one below the wafer and one above the wafer. Lower chamber 54
The airflow entering is radially outward while the upper chamber 56
Therein, the airflow is radially inward and exits through a plurality of holes 46 in the baffle disk 44. Since the intake disc 40 and the deflection disc 44 continuously receive heat from the wafer 18 by both thermal conduction and thermal radiation, heat is transferred from these components to the air as well as from the wafer 18. . Such a structure provides high efficiency because the heat conduction and heat radiation surfaces exposed to the air flow are almost doubled. The use of thermally conductive components in the intake disc 40 and the deflection disc 44 significantly increases the temperature inside the container.

The corrugated washer 42 is an important feature. These provide a favorable gap between the wafer 18 and the intake disc 40 and between the wafer 18 and the deflection disc 44, creating two separate chambers through which the dual airflows pass. 54
．． 56 is formed. The corrugated washer provides contact pressure between the annular terminal 30 and both sides of the wafer 18, reducing damage to the wafer.

Since the corrugated washer itself is not thick, the portion of the air stream that passes close to the corrugated washer is thus heated. The corrugated washer provides a conductive path for heat flow between the wafer 18 and the intake disk 40 and deflection disk 44.

The presence of the elastic piece 22 allows the heating element structure to be easily removed from the container, facilitating replacement and repair. The heating element structure according to the invention can be applied to existing container designs without modification.

The open-bottom design reduces the possibility of water entering the container.

Changes and modifications are possible.

[Brief explanation of the drawing]

FIG. 1 shows a part of a heating element structure according to the present invention, which is equipped with a disc-shaped heat insulating support structure and eight retaining pieces that can detachably support the heating element structure in an annular recess provided at the bottom of the container. FIG. 2 is a plan view and a partially sectional view. Figure 2 shows the first
FIG. 2 is a cross-sectional view taken along line 2-2 in the figure. FIG. 3 shows a partial cross-sectional view taken along line 3--3 of FIG. Fourth
The diagram is. 2 shows a partial cross-sectional view taken along line 4--4 of FIG. 1. FIG. FIG. 5 shows a partial cross-sectional view taken along line 5--5 of FIG. FIG. 6 is a partial view and a sectional view similar to FIG. 2 except that it is an enlarged view. FIG. 7 shows an end view of the flat heating element of the heating element structure shown in FIGS. 1 to 6, and arrows indicate air paths. FIG. 8 shows a partial view of the heating element structure of another embodiment of the present invention in which the intake disc and the deflection disc are metallized circuit boards. 15... activated carbon, 18... wafer, 30...
...Annular contact, 40...Intake adjustment disc body, 44 Air vent disc body, 52...Groove, 54...Lower chamber, 56...Upper chamber.

Claims (1)

[Claims] 1) a) A wafer made of an electrical resistance heating material and a mechanism for electrically contacting the wafer and energizing it; b) Spacious surfaces formed on both sides of the wafer; c) The wafer. d) a first wall with a spacious surface disposed on one side of the wafer and coextensive with one side of the wafer; e) a first chamber formed by these first walls and the wafer, and a second chamber formed by these second walls and the wafer; a lever communicating with the first chamber at the periphery of the wafer; and f) from the outside of the container into the first chamber through one side of the wafer and its periphery to the second chamber, the other side of the wafer. a mechanism for applying heat to a material suitable for alternately absorbing, storing and releasing fuel vapor contained in the container by directing air through the side of the container and into the interior of the container. An electrical heating element structure installed in the inlet port of a fuel vapor recovery vessel of a type containing materials suitable for alternate absorption, storage, and release. 2) a) a container contains a quantity of said fuel vapor absorption and release material, and b) said air directing mechanism includes an inlet hole and a mounting mechanism supporting said two walls and the wafer in a fixed position with respect to the container. An electrical heating element structure according to claim 1, comprising a molded plastic heating element case comprising: 3) a) The electric heating element structure according to claim 2, wherein the heating element case has a mechanism for detachably attaching the heating element case to the container. 4) The electrical heating element structure of claim 1, wherein a) said first wall comprises a perforated metal plate. 5) The electrical heating element structure as claimed in claim 1, wherein a) said second wall comprises a perforated metal plate. 6) The electric heating element structure as claimed in claim 1, wherein a) the first wall comprises a metallized heat insulating circuit board. 7) The electric heating element structure as claimed in claim 1, wherein a) the second wall comprises a metallized heat insulating circuit board. 8) a) The electric heating element structure according to claim 6, wherein the metal part of the circuit board faces the wafer. 9) a) The electric heating element structure according to claim 7, wherein the metal part of the circuit board faces the wafer. 10) a) the container comprises an inlet passage and an outlet passage;
An electrical heating element structure as claimed in claim 1 supporting an enclosure surrounding said wafer and a wall. 11) The electric heating element structure according to claim 1, wherein a) a spacer mechanism is provided between the wall and the wafer to maintain the wall and the wafer in a spaced relationship from each other. 12) A) The electrical heating element structure of claim 11, wherein a) the spacer mechanism comprises a pair of corrugated washers. 13) a) The electric heating element structure according to claim 1, wherein the wafer is a disc made of PTC ceramic material. 14) a) The mechanism for making the electrical connection consists of a pair of annular contacts provided on each side of the wafer, and b) A pair of lead wires respectively connected to these annular contacts.
Claim 2 protruding from the heating element case
The electrical heating element structure described in section. 15) a) The electric heating element structure according to claim 13, wherein the disk body is non-porous.