JPS6340126B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an air cleaner, and more particularly to a casing with an inlet and an outlet, and a pleated paper filter element mounted inside the casing to prevent air from entering the air cleaner during use. The present invention relates to an air cleaner of the type having a paper filter element with flow flowing through the element from an inlet to an outlet. More specifically, the present invention provides an air cleaner in which the filter element is generally tubular in the form of a truncated cone, the open end of the cone contacting the opposite end of the casing in sealing relationship with the casing. The air cleaner is arranged in such a way that the air flowing from the inlet to the outlet is constrained to pass through the tubular wall of said element.

The filter element itself is usually replaceable, and the casing allows this filter element to be replaced, either regularly or simply when the filter element becomes clogged by contaminants passing through the air. It is divisible for In order to maximize the time interval between such subsequent exchanges, the walls of the element are provided with the maximum available surface area for containing contaminants without unduly obstructing the inlet or outlet. It is highly desirable that the flow of contaminated air be evenly distributed over this surface area. The first of these requirements can be partially satisfied by making the outside of the element the inlet side for the contaminated air, but given the dimensions of the casing, the first The requirement of 2 limits the maximum possible diameter of the element. Unfortunately,
The dimensions of the casing are also very often limited by the space available to house it, which is a factor outside the control of the cleaner manufacturer, especially in the automotive industry.

Increasing the thickness of the filter element radially inward does increase the surface area, but due to the limited dimensions of the casing, the increase in thickness also means that the outlet is at least partially occupied as well as the element. This results in excessive pressure drop across.

Another complication arises when using pleated paper. The crests and valleys of the pleats typically extend in the axial direction of the element, with the depth of the pleats determining the radial thickness of the element. Obviously the spacing of the pleats and their depth have a large effect on the total available surface area of the paper in the cleaner, but an important practical consideration is the ease with which contaminant particles can penetrate into the pleats. be. If the spacing is too close and/or the pleats are too deep, a large surface area is available, but this surface area cannot be utilized well. This is because the walls defining the pleats, especially their radially innermost regions, are too close together.

The problem of increased pressure drop when reducing the diameter of the air cleaner casing (for a given power) and the problem of excessive air velocities around the element result in asymmetric dust distribution on the element surface. They arise in conjunction with problems. The problem of increasing pressure drop is the most serious, especially in the first
This is the case when the opening of is oriented in the tangential direction.

According to the invention, an air cleaner of the type employing a pleated paper filter element in the form of a truncated cone mounted within a tubular casing, said casing comprising a relatively wide section of said truncated cone; a first opening in the axial direction of the casing that communicates with the inside of the element at an end and in a cylindrical wall of the casing that communicates with the outside of the element near the relatively narrow end of the element; a second aperture, the axis of the element being inclined away from the second aperture with respect to the axis of the casing, such that the radial gap between the filter element and the aperture is An air cleaner is provided which is characterized in that it can be increased for a given filter element without increasing the dimensions of the filter element.

Preferably, the second opening is used as an inlet to the air cleaner, and the outlet is an axial opening communicating with the inside of the element. With such a structure, the entire area of the pleated paper constituting the filter element can be better utilized. This is because the outer surface of the element becomes more accessible to debris, especially at the bottom of the pleats.

Although the modification structure according to the invention significantly reduces the pressure loss or drop primarily on the filter element, the structure according to the invention also provides a (more uniform) distribution of debris over the entire area of the paper and on the filter element. It has the effect of reducing the surrounding air velocity. However, these latter two effects are somewhat less pronounced. For a given element and casing dimensions (length and diameter) and for a standard volumetric output, the aforementioned effect translates into an increase in the usable life of the filter element. This becomes noticeable when physical limitations prevent the use of large diameter casings. Of course, with proper selection, significantly higher outputs can be achieved for the same element service life.

The present invention can be combined with the invention described in patent application Ser. In fact, it is preferable to do so. This is because the combination provides better performance than either one invention alone.

For the present invention, the desired inclination of the filter element axis can be achieved in at least two ways. First, the opposing ends of the filter element can be arranged to lie in parallel planes at an angle to a plane perpendicular to the axis of the element. Second
Additionally, the end wall portions of the casing itself can be shaped to accommodate and place the normally symmetrical elements in an inclined axial position. It is preferable to do this. This is because the manufacture of the element is considerably simplified.

The filter element may also be in the form of two pleated paper truncated conical element sections assembled in a partially nested relationship, in which case the overlapping ends of the two sections define an annular space between them. They are joined together by non-permeable members to prevent leakage. Such embodiments are provided below in Section 3.
This will be explained with reference to the figures. The preferred construction shown requires that the two frustoconical element sections have a common axis that is inclined with respect to the axis of the casing as described above.

The present invention will be described in more detail below with reference to the accompanying drawings.

The structures in FIGS. 1 and 2 will be described first, and similar parts in both figures correspond to each other, so similar reference numerals will be used unless there is a practical problem. Referring to these figures, the air filter comprises a radial opening 1 in a cylindrical wall 2 and an axial opening 3 in one end wall 4.
It has a cylindrical casing with The other end is closed by a removable cover 5, which allows access to the filter element mounted in the casing. The details of how the cover 5 is attached are not important to the invention and will not be described in detail. The filter element consists of a pleated paper filter medium 7 supported by inner and outer tubes 8, 9, each constructed of perforated metal. The ends of the pleats and tubes are sealed within end caps 10,11. The cap 11 is provided with a conventional annular outer gasket 12 which prevents electrical conduction between the inside and outside of the filter element (other than the filter medium). Cap 10 includes a central sheet metal plate 13 which serves the same purpose as gasket 12.

Referring to FIG. 1, the filter element 6 has a generally frustoconical shape, but its ends lie in parallel planes at a slight angle to a plane perpendicular to the axis of the cone. The filter element is mounted in the casing in such a way that one of its sides is substantially parallel to the wall of the casing opposite the radial opening 1. By doing this, the axis of the filter element is slightly inclined with respect to the axis of the casing and the radial gap between the opening 1 and the outer perforated metal support tube 9 of the filter element is increased.

Reference is now made to Figure 2, which shows a frustoconical filter element mounted within the casing, in which the end wall 4 and the cover 5 themselves are inclined with respect to a plane perpendicular to the casing axis. are arranged in parallel planes. The effect is exactly the same as in FIG. 1, but the filter itself is symmetrical or conventional, with its ends lying in a plane substantially perpendicular to the axis of the cone. Although this construction has the advantage that only the casing needs to be changed, the cleaner of FIG. 1 requires special elements that must be fitted correctly. The elements of FIG. 2 are automatically mounted in the correct position without operator error. However, care must be taken when reattaching the cover 5. This is because the cover 5 must be keyed to the casing to ensure proper installation. This configuration is preferred over the configuration of Figure 1 given the relative ease of manufacture of the element shown in Figure 2. As previously mentioned, the first opening in the casing is the inlet to the cleaner and the axial opening is preferably the outlet. This is because such a shape allows the area of the paper within the filter element to be utilized most effectively.

The air cleaner of FIG. 2 was compared to a similar air cleaner in which the axis of the filter element is not tilted with respect to the axis of the casing. The cleaners were otherwise equal and had the following approximate dimensions:

Casing length 47 cm Number of pleats is 160, casing diameter 22 cm Pleat depth 3.8 cm Element length 46 cm Rating 17 m ³ /min Each element is 21 cm at its relatively wide end
has an outer diameter of , and its relatively narrow end is
It had an outer diameter of 18 cm. Both the inlet and outlet of the casing were slightly less than 13 cm in diameter.

When tested at rated power, the conventional cleaner had a pressure drop of about 12 cm of water, while the cleaner of the present invention had a pressure drop of about 8 cm of water. This reduction in pressure drop was significant for relatively small changes in cleaner geometry.

It will be appreciated that in order to minimize pressure drop across the cleaner, the diameter of the first opening in the casing should be substantially equal to the inner diameter of the filter element adjacent to the opening. . Similarly, the second opening should also have at least the same diameter.

Referring now to FIG. 3, the air cleaner has a cylindrical casing with a radial opening 20 in a cylindrical wall 21 and an axial opening 22 in one end wall. The opposite end is closed by a removable cover 24, which provides access to the filter element mounted within the casing. The details of the attachment of the cover to the casing are not important to the invention and therefore need not be described in detail. The filter element comprises two pleated paper truncated conical sections 25 and 26, each section having a perforated metal section in the same manner as just described above in connection with FIGS. 1 and 2. It is supported by inner and outer tubes (not shown). The frustoconical sections are assembled in a partially nested relationship, and their overlapping ends are fitted with an impermeable member 27 to prevent leakage through the annular space between the sections.
are connected by. The ends of said sections, together with their support tubes, are sealed to end caps 28, 29, 30 and 31, respectively. The cap 28 is provided with an annular sealing gasket 32 around the axial opening 22. The cap 31 contains a central sheet metal plate 33 for closing the ends of the element. Both parts have a frustoconical configuration and have a common axis that is inclined with respect to the axis of the casing. This is achieved because of the shape of the end walls of the casing, which end walls lie in parallel planes at an angle to a plane perpendicular to the axis of the casing. This allows the filter element to be symmetrical, resulting in a configuration that is simple to manufacture. The embodiment of FIG. 3 not only accommodates a large amount of filter paper for a given axial dimension of the casing, but the pleat spaces within the individual element sections are also optimized, making use of the resulting extra paper area. It can be used most effectively.

Although in the embodiment described above a radial inlet is provided to the casing, the invention is also useful with a tangential inlet.
In fact, the present invention includes significant advantages with respect to tangential intakes. This is because it is effective in reducing the problems introduced by tangential intakes in the structure of the present invention. That is, the vortex flow (around the element) induced by the tangential intake is not converted into static pressure on the outer surface of the element. Instead, the vortex gradually dissipates around the element, resulting in an increase in pressure drop (constraint) on the order of about 20%, which typically amounts to 2.5 cm of water. Tilting the element axis counters this loss by restricting the flow around the element and creating a stalling effect on air movement. The use of tangential intakes is often desirable for aesthetic reasons. Thus, by employing such an inlet, it is often possible to provide a cleaner piping assembly, for example along the rear wall of a vehicle cab. Employing the principles of the present invention allows for the use of tangential intakes in situations where cleaner performance would otherwise be preferred.

[Brief explanation of the drawing]

FIG. 1 is a schematic side cross-sectional view of one form of an air cleaner according to the invention, FIG. 2 is a schematic side cross-sectional view of another preferred embodiment of the invention, and FIG. 3 is a schematic side cross-sectional view of another preferred embodiment of the invention. It is a figure showing an example. 1: radial opening, 3: axial opening, 2: casing cylindrical wall, 4: end wall, 5: cover, 7:
Filter element, 10, 11: End cap, 1
2: Gasket, 13: Center sheet metal plate.

Claims (1)

Claims: 1. An air cleaner of the type employing a pleated paper filter element in the form of a truncated cone mounted within a tubular casing, said casing comprising a relatively wide width of said truncated cone. a first casing axially communicating with the inside of said element at an end of said element;
a second opening in the cylindrical wall of the casing communicating with the outside of the element near a relatively narrow end of the element, the axis of the element being inclined away from said second opening with respect to the axis of the casing, such that the radial gap between said filter element and said opening is increased for a given filter element without increasing the dimensions of the casing. An air cleaner characterized by: 2. The air cleaner according to claim 1, wherein the second opening is an intake port during use, and the axial opening is an outlet port. 3. In the air cleaner according to claim 1 or 2, the relative inclination of the filter element axis is such that the opposing ends of the element are in parallel planes that are not perpendicular to the axis of the element. An air cleaner characterized by: 4. In the air cleaner according to claim 1 or 2, the inclination of the filter element axis is provided by the shape of the end wall portion of the casing, and the portion is not perpendicular to the casing axis. 1. An air cleaner characterized in that the filter element is arranged in a parallel plane perpendicular to the axis of the filter element when installed in the casing. 5. An air cleaner according to any one of claims 1 to 4, wherein said element is in the form of two truncated conical sections assembled in a partially nested relationship; An air cleaner characterized in that the overlapping ends of the two parts are joined by a non-permeable member to prevent leakage through the annular space between the parts. 6. An air cleaner according to any one of claims 1 to 5, wherein the first opening in the casing has a diameter substantially equal to the inner diameter of an adjacent filter element. An air cleaner that is characterized by: 7. The air cleaner according to any one of claims 1 to 6, wherein the second opening is oriented in a tangential direction of the casing.