JP2005147317A - Sealing device and fuel injection pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sealing device, decreasing the number of parts, reducing the size of the device and attaining compatibility between pressure tightness and sealing performance, and a fuel injection pump including the sealing device. <P>SOLUTION: A main seal 12 is mounted on an annular groove 11b provided in a pressure reducing seal 11. The main seal 12 is slid on the shaft surface on the back side of a first seal lip 11a provided on the pressure reducing seal 11. The pressure reducing seal 11 mainly exhibits the pressure tightness and the main seal 12 mainly exhibits the sealing performance. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a sealing device for sealing an annular gap between two relatively moving members, and a fuel injection pump equipped with such a sealing device.

  For example, in a fuel injection pump used in a direct injection internal combustion engine, an annular gap between a reciprocating plunger and a cylinder is sealed by a sealing device (see, for example, Patent Document 1). The sealing device prevents the fuel on one side from leaking to the other through the sealing device, and prevents the lubricating oil on the other side from leaking to the other side. Here, since the fuel side has a high pressure, the sealing device is required to have pressure resistance. In particular, in recent years, the demand for pressure resistance has been increasing for sealing devices used in the fuel injection pumps for reasons such as exhaust gas regulations and fuel efficiency improvements.

  With reference to FIGS. 8 and 9, two examples of the sealing device used in the fuel injection pump according to the conventional example will be described. 8 and 9 are schematic cross-sectional views showing a usage state of the sealing device according to the conventional example. As shown in FIGS. 8 and 9, the sealing device according to the conventional example includes decompression seals 100 and 100 a and a main seal 200. The pressure reducing seal 100 of the sealing device according to the conventional example shown in FIG. 8 includes a resin seal ring 101 and a rubber seal ring 102. On the other hand, the decompression seal 100a of the sealing device according to the conventional example shown in FIG. 9 includes a resin-made seal ring 101a having a U-shaped cross section and a spring member 102a provided inside the seal ring 101a. The main seal 200 has the same configuration in any conventional example, and includes a metal ring 201 and a seal lip 202 provided on the metal ring 201.

  In the sealing device configured as described above, the pressure-reducing seals 100 and 100a mainly exert the pressure resistance performance, and the main seal 200 mainly exhibits the sealing performance. As described above, the reason why the pressure resistance performance and the sealing performance are exhibited by separate seals is as follows. That is, if importance is attached to pressure resistance performance, a highly rigid resin material can be suitably used, but in this case, the sealing performance is poor. On the other hand, if the sealing performance is regarded as important, a rubber material having high viscoelasticity can be suitably used, but in this case, the pressure resistance performance is inferior. Therefore, by using the decompression seals 100, 100a having the seal rings 101, 101a made of a resin material in combination with the main seal 200 made of a rubber material, the advantages of both are utilized and the disadvantages of both are compensated. It was like that.

By the way, in recent years, fuel injection pumps tend to be miniaturized, and there is an increasing demand for miniaturization of sealing devices. However, since the sealing device according to the conventional example has a configuration in which two types of seals are installed at two locations, it is difficult to meet the demand for downsizing.
JP 2003-21241 A

  One of the objects of the present invention is to reduce the size of the sealing device.

  Another object of the present invention is to reduce the number of parts.

  Another object of the present invention is to achieve both pressure resistance and sealing performance.

  The present invention employs the following means in order to solve the above problems.

That is, the sealing device of the present invention is a sealing device that seals an annular gap between two relatively moving members.
A reduced pressure seal having a seal lip that slides on one of the two members;
And a main seal mounted on a mounting portion provided on the pressure-reducing seal and sliding on the back side of the seal lip with respect to the one member.

  According to the configuration of the present invention, the pressure resistance performance is exhibited by the reduced pressure seal, and the sealing performance is exhibited by the main seal attached to the attachment portion provided in the reduced pressure seal. And, compared with the configuration in which the reduced pressure seal and the main seal are installed at different locations, the present invention can reduce the size of the sealing device because the main seal is mounted on the mounting portion of the reduced pressure seal, It is possible to reduce the number of parts.

  Here, the decompression seal is preferably made of a material having high rigidity (a material having rigidity higher than that of at least the main seal). Thus, by constructing the pressure reducing seal with a material having high rigidity, it is possible to sufficiently exert the pressure resistance performance. As a material having high rigidity, for example, a resin material such as PTFE can be cited as a suitable example.

  Further, the main seal may be made of a material having high viscoelasticity (at least a material having higher viscoelasticity than the reduced pressure seal). As described above, by configuring the main seal with a material having high viscoelasticity, the sealing performance can be sufficiently exhibited. As a material having high viscoelasticity, for example, a rubber material can be cited as a suitable example.

The fuel injection pump of the present invention is
In a fuel injection pump that injects fuel by pressurizing fuel in a pressurized chamber by a plunger that reciprocates in a cylinder,
An annular gap between the cylinder and the plunger is sealed by the sealing device.

  According to the configuration of the present invention, since the sealing device can be downsized, the fuel injection pump can be downsized.

  In addition, said each structure can be employ | adopted combining as much as possible.

  As described above, according to the present invention, the sealing device can be reduced in size and the number of parts can be reduced. Moreover, both pressure resistance and sealing performance can be achieved.

  The best mode for carrying out the present invention will be exemplarily described in detail below with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention only to those unless otherwise specified. .

With reference to FIG. 1, the sealing apparatus which concerns on Example 1 of this invention is demonstrated. FIG. 1 is a schematic cross-sectional view showing a usage state of a sealing device according to Embodiment 1 of the present invention. The sealing device 10 according to the present embodiment is used for sealing an annular gap between a shaft and a shaft hole through which the shaft provided in the housing is inserted. Here, the shaft and the housing are configured to reciprocate relatively. Further, the sealing device 10 according to the present embodiment is installed in an annular groove provided on the housing side.

  The sealing device 10 according to the present embodiment includes a decompression seal 11 and a main seal 12. The main body part (the part excluding the spring member 11e) of the decompression seal 11 is made of a resin material (for example, PTFE) having high rigidity and low frictional resistance. On the other hand, the main seal 12 is made of a rubber material having high viscoelasticity. The first sealing fluid side (O 1) and the second sealing fluid side (O 2) are blocked by the sealing device including the decompression seal 11 and the main seal 12. Here, in the present embodiment, the sealing fluid on the first sealing fluid side (O1) may be in a high pressure state.

  The decompression seal 11 includes a first seal lip 11a extending toward the first sealing fluid side (O1). The first seal lip 11a slides with respect to the shaft surface when the shaft and the housing move relative to each other. Further, the decompression seal 11 includes an annular groove 11b serving as a mounting portion to which the main seal 12 is mounted in the vicinity of the base of the first seal lip 11a. Further, the decompression seal 11 includes a second seal lip 11c and a protruding seal 11d that are in close contact with the inner peripheral surface of an annular groove provided in the housing. And in the pressure reduction seal | sticker 11, the cross-sectional shape of the part with which the 1st seal lip 11a and the 2nd seal lip 11c were provided is a substantially U shape. A spring member 11e is provided on the inner side of the substantially U-shaped section. The spring member 11e presses the first seal lip 11a toward the shaft surface and the second seal lip 11c toward the inner peripheral surface of the annular groove provided in the housing.

  The main seal 12 is mounted in an annular groove 11 b provided in the pressure reducing seal 11. The main seal 12 is a D ring having a substantially D-shaped cross section. When the shaft and the housing move relative to each other, the inner periphery of the main seal 12 slides on the shaft surface. Further, the outer peripheral side of the main seal 12 is in close contact with the inner peripheral surface of the annular groove 11b. Further, the main seal 12 exerts an action of pressing the decompression seal 11 in the outer diameter direction by its elastic repulsion force. Thereby, the sealing function by the protruding seal 11d provided in the decompression seal 11 is more effectively exhibited.

  As described above, the first sealing fluid side (O1) and the second sealing fluid side (O2) are shut off by the sealing device 10 including the decompression seal 11 and the main seal 12. Here, as described above, the first sealed fluid side (O1) may be in a high pressure state. Therefore, the sealing device 10 is required to have pressure resistance performance and sealing performance. And in the sealing device 10 which concerns on a present Example, the pressure reduction seal | sticker 11 mainly exhibits the pressure resistance performance, and the main seal 12 mainly exhibits the sealing performance. That is, as described above, the decompression seal 11 is made of a highly rigid resin material and has excellent pressure resistance. On the other hand, the main seal 12 is made of a rubber material having high viscoelasticity and has excellent sealing performance.

In the present embodiment, the main seal 12 is configured to slide relative to the shaft surface on the back side of the first seal lip 11 a provided in the decompression seal 11. Therefore, only the decompression seal 11 is exposed to the first sealing fluid side (O1), and the main seal 12 is not exposed to the first sealing fluid side (O1). Thereby, even if the 1st sealing fluid side (O1) becomes a high pressure state, the main seal 12 does not receive a high pressure directly. Therefore, the main seal 12 exhibits sufficient sealing performance and suppresses deterioration over time. However, the decompression seal 11 is inferior in sealing performance compared to the main seal 12. Therefore, the first sealing fluid may leak to the second sealing fluid side (O2) from the sliding portion of the first seal lip 11a. However, the main seal 12 having excellent sealing performance prevents the first sealing fluid from leaking to the second sealing fluid side (O2). The second sealing fluid is also prevented from leaking to the first sealing fluid side (O1) by the main seal 12.

  As described above, the pressure-reducing seal 11 mainly exhibits the pressure resistance performance, and the main seal 12 mainly exhibits the sealing performance, whereby the demand for the pressure resistance performance and the demand for the sealing performance can be met by the single sealing device 10. Further, by providing the main seal 12 on the back side of the first seal lip 11a provided in the decompression seal 11, the disadvantages of the both (the main seal 12 is inferior in pressure resistance and the decompression seal 11 is inferior in sealing performance). Can supplement each other. In addition, the angle which the front-end | tip of the 1st seal lip 11a makes with the shaft surface becomes larger on the inclined surface on the first sealing fluid side (O1) than on the inclined surface on the second sealed fluid side (O2). Is set to Accordingly, when the first seal lip 11a and the shaft relatively reciprocate, the amount of the sealing fluid pushed out to the first sealing fluid side (O1) rather than the amount of the sealing fluid drawn into the second sealing fluid side (O2). There are more. Therefore, the fluid pressure in the sealed region between the first seal lip 11a and the main seal 12 is prevented from becoming higher than the pressure on the first sealed fluid side (O1).

  Here, the decompression seal 11 made of a material having high rigidity has a larger amount of strain over time due to creep than the main seal 12 made of a rubber material. In particular, the first seal lip 11a is also worn by sliding. However, in this embodiment, since the spring member 11e is provided, the sliding state with respect to the shaft surface of the first seal lip 11a and the close contact state with respect to the housing of the second seal lip 11c are stably maintained. Therefore, the deterioration with time of the sealing performance of the decompression seal 11 is suppressed. Furthermore, in this embodiment, the cross-sectional shape of the portion provided with the first seal lip 11a and the second seal lip 11c is substantially U-shaped. Therefore, each seal lip is pressed outward by the pressure of the sealing fluid inside this portion. That is, the pressure by the sealing fluid is added to the pressing force by the spring member 11e. Therefore, the deterioration with time of the sealing performance of the decompression seal 11 is more reliably suppressed.

  As described above, according to the sealing device 10 according to the present embodiment, the pressure resistance performance and the sealing performance can be exhibited with a single device. And compared with the structure which installs a pressure_reduction | reduced_pressure seal | sticker and a main seal in a different location, it can aim at reduction of a number of parts, size reduction of a sealing device, and reduction of arrangement space. In addition, this makes it possible to reduce assembly man-hours. Furthermore, these lead to cost reduction.

  Next, a preferred application example of the sealing device 10 according to the present embodiment will be described. A direct injection internal combustion engine is provided with a fuel injection pump for injecting fuel. For example, a fuel injection pump configured to inject fuel by pressurizing fuel in a pressurizing chamber with a plunger that reciprocates in a cylinder is known (the fuel injection pump is known in the art). Because there is, detailed explanation is omitted). In such a fuel injection pump, it is necessary to seal an annular gap between a reciprocating plunger (corresponding to a shaft) and a cylinder (corresponding to a housing). Therefore, the sealing device 10 described above can be suitably applied to seal the annular gap.

The sealing device 10 applied in this way shuts off the fuel (corresponding to the first sealing fluid) and the lubricating oil (corresponding to the second sealing fluid) on the pressurized chamber side. The sealing device 10 must prevent the fuel from leaking from the pressurizing chamber side and prevent the lubricating oil from entering the pressurizing chamber. Further, the pressure on the pressurized chamber side is very high. However, as described above, since the sealing device 10 has both pressure resistance and sealing performance, when used in such a fuel injection pump, the function is sufficiently exhibited. In recent years, fuel injection pumps tend to be miniaturized, but as described above, the sealing device 10 according to the present embodiment can sufficiently meet the demand for miniaturization.

  FIG. 2 shows a second embodiment of the present invention. FIG. 2 is a schematic cross-sectional view showing a usage state of the sealing device according to the second embodiment of the present invention. In the said Example 1, the case where the main seal was a D ring was shown. On the other hand, the sealing device 10a according to the present embodiment shows a case where the main seal 12a is an O-ring. Even in this case, it goes without saying that the same effects as those of the first embodiment can be obtained. The decompression seal 11 is the same as that in the first embodiment, and a description thereof will be omitted.

  FIG. 3 shows a third embodiment of the present invention. FIG. 3 is a schematic cross-sectional view showing a usage state of the sealing device according to Embodiment 3 of the present invention. The sealing device 20 according to this embodiment includes a decompression seal 21, a main seal 22, and an outer peripheral seal 23. That is, also in the present embodiment, the main seal 22 is mounted in the annular groove 21 a provided on the inner peripheral side of the pressure reducing seal 21 as in the first embodiment. Further, in this embodiment, an annular groove 21b is also provided on the outer peripheral side of the decompression seal 21, and the outer peripheral seal 23 is attached thereto. Here, each of the main seal 22 and the outer peripheral seal 23 is a D-ring made of a rubber material. In the present embodiment, since the sealing device 20 and the housing are also sealed by the outer peripheral seal 23 made of a rubber material having excellent sealing performance, the sealing performance is further improved as compared with the first embodiment. The decompression seal 21 is made of a resin material, and the main seal 22 is made of a rubber material as in the first embodiment.

  FIG. 4 shows a fourth embodiment of the present invention. FIG. 4 is a schematic cross-sectional view showing a usage state of the sealing device according to Embodiment 4 of the present invention. In the said Example 3, the case where the main seal and the outer periphery seal were D rings was shown. On the other hand, the sealing device 20a according to the present embodiment shows a case where the main seal 22a and the outer peripheral seal 23a are O-rings. Even in this case, it is needless to say that the same effect as in the third embodiment can be obtained. Since the decompression seal 21 is the same as that in the third embodiment, the description thereof is omitted.

  FIG. 5 shows a fifth embodiment of the present invention. FIG. 5 is a schematic cross-sectional view showing a usage state of the sealing device according to Embodiment 5 of the present invention. Also in the sealing device 30 according to the present embodiment, similarly to the first embodiment, the pressure reducing seal 31 made of a resin material and the rubber material mounted in the annular groove provided in the pressure reducing seal 31 are also configured. The main seal (D ring) 32 is provided. In the present embodiment, the shape of the decompression seal 31 is different from that of the first embodiment. That is, in this embodiment, the outer peripheral side of the decompression seal 31 is configured so that the entire surface is in close contact with the housing. In the first embodiment, the seal lip (first seal lip 11a) that slides on the shaft surface is easily bent and deformed, whereas in this embodiment, the seal lip 31a that slides on the shaft surface. Has a shape that is not so bent and deformed. In this embodiment, the spring member is not used as in the first embodiment.

  In the present embodiment, since the shape and structure of the decompression seal 31 is simplified, depending on the material and usage conditions, wear due to sliding of the seal lip 31a, and distortion over time due to creep are not a significant problem. It is valid.

FIG. 6 shows a sixth embodiment of the present invention. FIG. 6 is a schematic cross-sectional view showing a usage state of the sealing device according to Embodiment 6 of the present invention. In the said Example 5, the case where the main seal was a D ring was shown. On the other hand, the sealing device 30a according to the present embodiment shows a case where the main seal 32a is an O-ring. Even in this case, it goes without saying that the same effects as those of the fifth embodiment can be obtained. The decompression seal 31 is the same as that in the fifth embodiment, and a description thereof will be omitted.

  FIG. 7 shows a seventh embodiment of the present invention. FIG. 7 is a schematic cross-sectional view showing a usage state of the sealing device according to Embodiment 7 of the present invention. The present embodiment is a modification of the third embodiment, and is an embodiment in which the seal lips of the decompression seal are provided symmetrically.

  That is, the sealing device 40 according to the present embodiment includes a decompression seal 41, a main seal 42, and an outer peripheral seal 43. The decompression seal 41 includes a first seal lip 41a extending toward the first sealing fluid side (O1) and a first seal lip 41b extending similarly toward the second sealing fluid side (O2). These first seal lips 41a and 41b slide relative to the shaft surface when the shaft and the housing move relative to each other. Further, the decompression seal 41 includes an annular groove 41c serving as a mounting portion to which the main seal 42 is mounted in the vicinity of the roots of the first seal lips 41a and 41b. The decompression seal 41 is provided with second seal lips 41e and 41f that are in close contact with the inner peripheral surface of an annular groove provided in the housing. Further, the decompression seal 41 includes an annular groove 41d serving as a mounting portion to which the outer peripheral seal 43 is mounted in the vicinity of the bases of the second seal lips 41e and 41f. In the decompression seal 41, the cross-sectional shape of the portion provided with the first seal lip 41a and the second seal lip 41e is U-shaped, and similarly, the first seal lip 41b and the second seal lip 41f. The cross-sectional shape of the portion provided with is U-shaped. And spring members 41g and 41h are provided inside these U-shaped sections.

  According to the sealing device 40 according to the present embodiment, the pressure resistance performance is exhibited not only on the first sealing fluid side (O1) but also on the second sealing fluid side (O2). Therefore, when the pressure of the sealing fluid on both sides becomes high, the sealing device 40 according to the present embodiment can be suitably used.

(Other)
In each of the embodiments described so far, the case where the main seal is a D-ring or an O-ring has been shown. In Examples 1, 2, 3, 4, and 7, a configuration including a spring member was shown to stably slide or closely contact the first seal lip and the second seal lip with respect to the counterpart member. . However, if there is no particular problem depending on the use environment or the like, it is possible to eliminate the spring member and simplify the configuration. Furthermore, in each Example demonstrated so far, the structure which installs a sealing device in the annular groove provided in the housing side was demonstrated. However, the present invention is not limited to this, and a configuration in which a sealing device is installed in an annular groove provided on the shaft side can be employed. In this case, the seal lip and the main seal slide with respect to the housing. Moreover, although the said Example demonstrated as a sealing device used for reciprocation, it can be used also as a sealing device for rotation or rocking | fluctuation.

FIG. 1 is a schematic cross-sectional view showing a usage state of a sealing device according to Embodiment 1 of the present invention. FIG. 2 is a schematic cross-sectional view showing a usage state of the sealing device according to the second embodiment of the present invention. FIG. 3 is a schematic cross-sectional view showing a usage state of the sealing device according to Embodiment 3 of the present invention. FIG. 4 is a schematic cross-sectional view showing a usage state of the sealing device according to Embodiment 4 of the present invention. FIG. 5 is a schematic cross-sectional view showing a usage state of the sealing device according to Embodiment 5 of the present invention. FIG. 6 is a schematic cross-sectional view showing a usage state of the sealing device according to Embodiment 6 of the present invention. FIG. 7 is a schematic cross-sectional view showing a usage state of the sealing device according to Embodiment 7 of the present invention. FIG. 8 is a schematic cross-sectional view showing a usage state of a sealing device according to a conventional example. FIG. 9 is a schematic cross-sectional view showing a use state of a sealing device according to a conventional example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10,10a Sealing device 11 Pressure reducing seal 11a First seal lip 11b Annular groove 11c Second seal lip 11d Protruding seal 11e Spring member 12, 12a Main seal 20, 20a Sealing device 21 Pressure reducing seal 21a, 21b Annular groove 22, 22a Main Seal 23, 23a Peripheral seal 30, 30a Sealing device 31 Pressure reducing seal 31a Seal lip 32a Main seal 40 Sealing device 41 Pressure reducing seal 41a, 41b First seal lip 41c, 41d Annular groove 41e, 41f Second seal lip 41g, 41h Spring member 42 Main seal 43 Outer seal

Claims (4)

In a sealing device for sealing an annular gap between two relatively moving members,
A reduced pressure seal having a seal lip that slides on one of the two members;
And a main seal mounted on a mounting portion provided on the pressure-reducing seal and sliding on the back side of the seal lip with respect to the one member. The decompression seal is made of a material having higher rigidity than the main seal,
The sealing device according to claim 1, wherein the main seal is made of a material having higher viscoelasticity than the decompression seal. The vacuum seal is made of a resin material,
The sealing device according to claim 1, wherein the main seal is made of a rubber material. In a fuel injection pump that injects fuel by pressurizing fuel in a pressurized chamber by a plunger that reciprocates in a cylinder,
An annular gap between the cylinder and the plunger is sealed by the sealing device according to claim 1, 2, or 3.

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