JPS597068B2 - gasket - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to gaskets, and more particularly to collapse knotted and metal jacketed gaskets used under high temperature and/or high pressure loads.

As is well known, at least the periphery of the opening for fluid flow is made of iron, stainless steel, etc. with a thickness of 0.05 to 0. Grommeted and metal jacketed gaskets with approximately 3% thin metal sheets are used in many industrial machines, various devices, and internal combustion or external combustion engines such as automobiles and ships, especially for high-temperature and/or high-pressure fluids. It has been widely used as an effective gasket between the joint surfaces of equipment in which fluid flows.

However, such a gasket with a thin metal plate, as shown by the symbol C in FIG.
This included serious defects such as cracks occurring at the peripheral edge of the thin metal plate near the opening peripheral edge, resulting in leakage of fluid and a reduction in sealing effectiveness.

Therefore, in order to prevent the occurrence of such cracks, attempts have been made to increase the thickness of the thin metal sheet and improve the material of the thin metal sheet, especially its rigidity.

However, in the case of an increase in wall thickness, accurate attachment of the metal sheet, especially at the periphery of the opening, becomes difficult, and, for example, a rectangular shaped opening (this is a configuration that is applied in a wide range of fields).

) When a thin metal plate is wrapped around and expanded into a gasket having a gasket having This is also a frequently used configuration when the openings with and without sheet metal are formed in the same gasket.

), it has the disadvantage that the surface pressure near the opening periphery where there is no thin metal plate cannot reach a predetermined value.

On the other hand, even when improving the material quality of the thin metal sheet, particularly its rigidity, there are similar drawbacks such as distortion of the surface of the metal sheet, deterioration of the material quality at bent portions, and increased material costs.

Furthermore, in both of the above cases, although there is a time delay, it is not possible to completely avoid cracking as shown by C in the end, and fluid leakage due to aging is still substantially prevented. It was something that could not be resolved.

Furthermore, when cracking as described above occurs, it also causes substantial fusion of the thin metal plate to the joint surface, causing a shift in the relative positional relationship between the gasket and the joint surface.
A phenomenon occurs in which the peripheral edge of the fluid opening of the gasket 1- protrudes into the fluid opening of the joint surface, thereby inhibiting the normal flow of fluid.

Therefore, an object of the present invention is to provide a gasket in which at least the periphery of the opening is covered and expanded with a thin metal plate, which does not crack even when used under high temperature and/or high pressure loads. be.

Another object of the present invention is to provide a gasket that can effectively prevent the above-mentioned cracking without using special members.

Another object of the present invention is to prevent cracking even under severe conditions such as cylinder head gaskets and manifold gaskets of internal combustion engines where high temperature and high pressure loads are applied periodically and intermittently. Our goal is to provide fearless gaskets.

Still another object of the present invention is to provide a gasket that always maintains a relative positional relationship with the joint surface of the gasket, thereby not inhibiting the normal flow of fluid.

The present invention will be explained below with reference to the drawings using a gasket with a 11% suspension as an example, but it will be explained later that the same applies to gaskets of metal jacket type and other shapes in which thin metal plates are applied to the periphery of the fluid opening. It can be easily understood from.

Possible causes of cracks as described above occurring in gaskets that are subjected to high temperature and/or high pressure loads include changes in the material itself such as oxidation due to periodic and/or intermittent high heat application, and bonding. Weakening due to mechanical vibrations caused by pressure changes in parts not sandwiched between surfaces, weakening due to induced vibrations in non-pinched parts due to mechanical vibration of joint surfaces, or chemical changes due to retention of corrosive fluid between joint surfaces. etc. were considered.

Therefore, typically, stainless steel (SUS304), which is the most common metal sheet, has a wall thickness of 0.1 and 0.1.
3% and a wall thickness of 0.3% with better heat resistance and stiffness.
A cylinder head gasket for a two-cylinder engine having a grommeted cylinder bore opening A, as shown by reference numeral G, made of 1X cold rolled steel material (SPCB, for deep drawing) (Fig. 2). (Reference) were made, 5 of each were assembled into the engine by conventional means, and 3000
Measurements were conducted under a high temperature and high pressure load that was applied periodically or intermittently by repeating 1 hour of continuous operation at RPM, followed by 1 hour of rest, and checking for cracks in the grommet. The average time until cracks occur, converted to actual operating time (actual working time), is as follows.

Stainless steel (0.1% thickness) 5.8 hours tt (Q, 3% thickness) 14.6 hours Cold rolled steel plate (0.1% friction) 19.2 hours Also, three types of gaskets similar to those mentioned above As shown in FIG. 3, the positional deviation d of the opening A with respect to the joint surface was measured at the time of assembly and after 36 hours of actual operation, and the average value was as follows.

Stainless steel (o.i'x thickness) 5.3% Stainless steel (0.3% nominal) 4.9% Cold rolled steel plate (0.1% thickness) 4.4% Here, as is well known, the opening Although the circumference of A is dimensioned and arranged so as to have a space of about 0.3 to 0.5X between it and the fluid hole H on the joint surface, in each of the above-mentioned gaskets, the circumference of all openings A is It will be easily understood that the portion protrudes into the fluid hole H and obstructs the normal flow of fluid.

As a result, it has been found that cracks occurring in the grommet and misalignment of the gasket cannot be resolved simply by improving the material and increasing the wall thickness.

Therefore, the cause of the occurrence of cracks was reexamined, and the following was proven through experiments described below.

That is, a) Thermal expansion occurs in the parts having joint surfaces (in the case of this measurement and experiment, the cylinder head and cylinder block) and the grommet due to the thermal load of the fluid.

b) The coefficient of thermal expansion varies depending on the type of object, for example, aluminum alloy forming the cylinder head (ADC 1)
is 21.0~2 1. 8 X 10'3/'C, and the cast iron forming the cylinder fins is 11X10-
The stainless steel (SUS 304) that forms the grommet is 1 8.4 x 1.
0-6/°C, which is an intermediate value between the two, and it is assumed that the difference in the expansion coefficient of each part due to the same overall heat load is the main factor that causes cracking of the grommet. confirmed.

Experimental example 1 Wall thickness of 0.1% where cracking occurs in an extremely short time as described above
Five 2-cylinder cylinder head gaskets fitted with stainless steel (SUS304) grommets were made, and as shown in Figure 4, each grommet G had a wall thickness of 0.0 mm on both sides.
1-0.2%, friction coefficient o. I ~ 0.2 graphite was attached by baking, coating, pasting, or other suitable well-known means, and continuous operation for 1 hour and rest for 1 hour was continued for 3 days (actual working time 36 hours), but no cracks were visible. Ta.

After that, after repeating 6 hours of continuous operation, 2 hours of rest, and visual inspection of cracks for one week, a minute crack was visible on only one of the 10 grommets when checking the 158th hour of actual working time. It was done.

Continuous operation for 12 hours followed by 12 hours of rest and visual inspection was continued, but no cracks appeared on the other brains even after 30 days, ie, 522 hours of actual working time.

In this case, the cracked knots were found to have cracks in the areas where the graphite had peeled off because the graphite was not completely adhered to the knots.

Experimental Example 2 An experiment was conducted under the same conditions as Experimental Example 1 using a gasket in which molybdenum disulfide (0.01 to 0.2% and molybdenum disulfide with a friction coefficient of 0.04 to 0.1) was similarly attached to both sides of Gromez L-G. However, in the end, no cracks could be visually observed on the groove.

Experimental Example 3 An experiment was conducted in the same manner as in the previous example using boron nitride, which has a friction coefficient of 0.04 to 0 and is particularly effective as a high-temperature lubricant, but cracks in the grommet were not visually recognized in the end. I couldn't.

Experimental Example 4 Using three types of gaskets in which graphite 1, molybdenum disulfide, and boron nitride were attached to the grommet G as the lubricant L tested in each of the experimental examples above, continuous operation was continued for 8 hours every day. When the test was carried out for 90 days, no cracks were visible on any of the grommets, except that the cracks that had appeared on one of the grommets to which graphite was attached, as described in Experimental Example 1, had spread by about 2.8 times.

Furthermore, these grommets were inspected for flaws using X-rays, but no internal cracks were found.

Here, the average surface temperature of the joint surface during each experiment was about 860'C, and the load pressure was about 85 kg/cII.
It was L.

It should also be noted that there was virtually no difference in sealing performance, which is the original purpose of gasketing, between before and after the experiment started.

Experimental Example 5 Five similar gaskets with graphite, molybdenum disulfide, and boron nitride attached to the chrysanthemum knot described above and gaskets with no attachment were made, and the gaskets were operated continuously for 8 hours per day for 90 days. The following results were obtained by measuring the deviation dimension d between the gasket and the joint surface and the protrusion dimension t of the opening peripheral portion of the gasket into the cylinder bore (see FIG. 3).

These experiments have shown that by interposing a lubricant between the joint surface and the gasket, it is possible to reliably prevent cracks from occurring in the grommet or the thin metal plate covering the opening periphery, and to ensure that the gasket is in the specified position. It turns out that it can be maintained at

This is because, as schematically shown in Fig. 5, each joint surface and the knot can expand and contract separately due to heat load, etc., and before the start of operation, the solid line As shown, one joint surface CH and the corresponding joint surface C
The gasket having the grommets I-G sandwiched between the gasket and the gasket B is held in a fixed positional relationship by the mounting bolt B.

When operation is started, that is, when a fuel load or the like is applied, each portion expands outward as a whole as shown by a dashed line Y.

At this time, each part expands differently due to the difference in the expansion coefficient of each part, but both joint surfaces CH and C
The lubricant L interposed between B and the grommet G facilitates desired positional movement (expansion).

When the operation is stopped, conversely, contraction begins in the direction shown by the broken line Z, but each part can easily perform the desired positional movement as described above.

This means that there is no risk of restricting the positional movement of each part, especially the grommet made of thin plate members, and mechanical strain (
In other words, this means reliably avoiding the occurrence of cracks, etc.).

In the above experiment, graphite, molybdenum disulfide, and boron nitride were used as the lubricant L, but depending on the load conditions on the applied joint surface and the type of fluid, PTF
Synthetic resin members such as E and EEP, metal members such as lead, silver, and gold, and solid lubricants such as gelenide, mica, and tungsten disulfide can be used.

However, from the viewpoint of manufacturing cost, handling, durability, etc., graphite and molybdenum disulfide are most suitable for high temperature and/or high pressure gaskets.

Furthermore, the thickness of the lubricant L applied to the surface of the grommet or grommet-corresponding portion should be as thin as 0.01 to 0.2%, as suggested in the above-mentioned experimental example. Essentially, when the lubricant L is installed between the joint surfaces, the lubricant L will have the desired effect if a thickness that can maintain the lubricating properties is left between the grommet or the grommet-corresponding portion and the joint surface. The purpose and effect can be fully achieved.

On the other hand, if the wall thickness of the lubricant L is set to be large, the lubricant L will be damaged due to mechanical vibration of the tightening surface or the joint surface when it is installed between the joint surfaces, stress from the flowing fluid, etc. This will cause loss of gas and reduce the sealing effect, which is the main purpose of the gasket.

As described above, according to the present invention, by attaching a lubricant so that it is interposed between the joint surface applied to a gasket with a grommet or a metal jacket type, etc.
This not only reliably prevents the thin metal plate around the fluid-conducting opening from cracking that would cause fluid leakage, but also allows the conventional thin metal plate to be completely fused to the joint surface, making the opening's periphery more ideal for fluid conduction. It is possible to create a gasket that does not protrude into the mouth and obstruct its flow, and unlike conventional methods, increasing the thickness of the thin metal plate prevents insufficient blood pressure at the opening covered by the thin non-metal plate, and the high quality of the material. This is extremely useful as it can avoid the rise in manufacturing prices due to

In each of the above experiments, a gasket was explained in which lubricant was attached to both sides of the Gubushimet, but depending on the applicable joint surface, the gasket may be applied only to one side and be substantially integrated with one joint surface. , and the other joint surface, which has larger factors such as temperature changes, can perform a lubricating action, and there is no limitation on the range to which the lubricant is applied, such as metal jacket type gaskets, etc. If a thin metal plate is spread over the entire surface of the gasket, as in the case of the gasket, it is also possible to apply lubricant to the entire surface.

[Brief explanation of the drawing]

Figure 1 is a diagram explaining cracks in the grommet, Figure 2 is a diagram showing a gasket as a sample for measurement and experimentation in the present invention, Figure 3 is an explanatory diagram of measurement and experiment points, and Figure 4 is Figure 2. FIG. 5 is a cross-sectional view of the gasket according to the present invention shown in FIG.

Claims (1)

[Claims] 1 A gasket with a grommet processing type or metal jacket type structure, which has a metal grommet or a portion corresponding to a grommet of a thin metal plate member on the periphery of the opening through which high-temperature and/or high-pressure fluid flows, and has a grommet-processed or metal jacket-type structure with On at least one surface of the grommet or the surface of the grommet-corresponding portion of the thin plate member that comes into contact with the grommet,
Graphite, molybdenum disulfide, boron nitride, or a lubricating material having similar properties is applied to the entire surface between the grommet or grommet-corresponding part and the joint surface at a thin enough thickness to maintain lubrication. A gasket characterized by: