CN220601803U

CN220601803U - Auxiliary air inlet type smoke exhaust pipe of balance type gas water heater

Info

Publication number: CN220601803U
Application number: CN202222986159.8U
Authority: CN
Inventors: 张永
Original assignee: Individual
Current assignee: Individual
Priority date: 2022-11-09
Filing date: 2022-11-09
Publication date: 2024-03-15
Anticipated expiration: 2032-11-09

Abstract

The utility model discloses an auxiliary air inlet type smoke exhaust pipe of a balanced gas water heater, which comprises a main pipe and an auxiliary pipe connected and communicated with the main pipe; the main pipeline comprises an exhaust inner pipe and an air inlet outer pipe fixedly sleeved outside the exhaust inner pipe, an exhaust channel is formed inside the exhaust inner pipe, a first air inlet channel is formed between the outer wall of the exhaust inner pipe and the inner wall of the air inlet outer pipe, and the exhaust inner pipe and the air inlet outer pipe both comprise an outdoor section extending outdoors and an indoor section connected with the water heater and positioned indoors; the second air inlet pipeline is formed inside the auxiliary pipeline, the first end of the auxiliary pipeline is connected with the indoor section of the air inlet outer pipe, the second air inlet pipeline is communicated with the first air inlet pipeline, and the second end of the auxiliary pipeline can extend out of the air chamber with the outdoor section of the air inlet outer pipe.

Description

Auxiliary air inlet type smoke exhaust pipe of balance type gas water heater

Technical Field

The utility model relates to the field of smoke exhaust pipes of gas water heaters, in particular to an auxiliary air inlet type smoke exhaust pipe of a balanced gas water heater.

Background

The gas water heater is also called as gas water heater, which uses gas as fuel to transfer heat to cold water flowing through heat exchanger by combustion heating mode to achieve the purpose of preparing hot water.

Most of the existing gas water heaters adopt a smoke exhaust pipe comprising a double-layer pipe body, the double-layer smoke exhaust pipe comprises an inner pipe and an outer pipe, the inner pipe is used for exhausting smoke, and an air inlet channel between the outer pipe and the inner pipe is used for allowing air to enter the water heater to be combusted.

When the existing water heater is used in cold weather, the temperature of exhaust gas discharged by the inner pipe of the smoke exhaust pipe is higher, and the temperature of air entering from the outer pipe is lower, so that condensed water is alternately generated in the cold and hot air inlet channels between the inner pipe and the outer pipe, after the water heater is stopped in use, the outdoor section of the smoke exhaust pipe is rapidly cooled, the condensed water attached to the air inlet channels or the outer pipe is frozen, and the air inlet holes and even the air inlet channels on the outer pipe of the smoke exhaust pipe are blocked by ice cubes. When the water heater is used next time, air cannot enter the water heater through the outer tube of the smoke exhaust tube, and normal use of the water heater is affected.

Disclosure of Invention

The utility model aims at the defects of the prior art and provides an auxiliary air inlet type smoke exhaust pipe of a balanced gas water heater.

The technical scheme adopted for solving the technical problems is as follows: constructing an auxiliary air inlet type smoke exhaust pipe of the balance type gas water heater, wherein the smoke exhaust pipe comprises a main pipe and an auxiliary pipe which is connected and communicated with the main pipe;

the main pipeline comprises an exhaust inner pipe and an air inlet outer pipe fixedly sleeved outside the exhaust inner pipe, an exhaust channel is formed inside the exhaust inner pipe, a first air inlet channel is formed between the outer wall of the exhaust inner pipe and the inner wall of the air inlet outer pipe, and the exhaust inner pipe and the air inlet outer pipe both comprise an outdoor section extending outdoors and an indoor section connected with the water heater and positioned indoors;

the second air inlet pipeline is formed inside the auxiliary pipeline, the first end of the auxiliary pipeline is connected with the indoor section of the air inlet outer pipe, the second air inlet pipeline is communicated with the first air inlet pipeline, and the second end of the auxiliary pipeline can extend out of the air chamber with the outdoor section of the air inlet outer pipe.

In the auxiliary air inlet type smoke exhaust pipe of the balanced gas water heater, the second end of the auxiliary pipe extends towards the outdoor section direction of the air inlet outer pipe to form an extending section which can extend outdoors, and the extending section of the auxiliary pipe is basically parallel to the outdoor section of the air inlet outer pipe.

In the auxiliary air inlet type smoke exhaust pipe of the balanced gas water heater, a first air inlet hole communicated with the first air inlet channel is formed in the side wall of the outdoor section of the air inlet outer pipe, an air outlet hole communicated with the air exhaust inner pipe is further formed in the side wall of the outdoor section of the air inlet outer pipe, and a second air inlet hole communicated with the second air inlet channel is formed in the side wall of the extending section of the auxiliary pipe.

In the auxiliary air inlet type smoke exhaust pipe of the balanced gas water heater, the air inlet outer pipe at least comprises a first straight pipe connected with the water heater, a second straight pipe different from the first straight pipe in the length direction, and a connecting pipe connected with and communicated with the first straight pipe and the second straight pipe, and the outdoor section of the air inlet outer pipe is positioned at the second end of the second straight pipe;

the auxiliary pipeline comprises a first pipe body and a second pipe body which are connected and communicated with each other, the first pipe body is fixedly connected and communicated with the indoor section of the second straight pipe, and the second pipe body and the second straight pipe are basically arranged in parallel.

In the auxiliary air inlet type smoke exhaust pipe of the balanced gas water heater, the air inlet outer pipe at least comprises a third straight pipe connected with the water heater, a fourth straight pipe different from the third straight pipe in the length direction, a fifth straight pipe different from the fourth straight pipe in the length direction, a second connecting pipe connected with and communicated with the third straight pipe and the fourth straight pipe, and a third connecting pipe connected with and communicated with the fourth straight pipe and the fifth straight pipe, wherein the outdoor section of the air inlet outer pipe is positioned at the second end of the fifth straight pipe;

the first end of the auxiliary pipeline is fixedly connected and communicated with the fourth straight pipe, and the auxiliary pipeline and the fifth straight pipe are basically arranged in parallel.

In the auxiliary air inlet type smoke exhaust pipe of the balanced gas water heater, a one-way valve which only allows outdoor air to flow to the water heater in one way is arranged on the auxiliary pipe.

In the auxiliary air inlet type smoke exhaust pipe of the balanced gas water heater, the one-way valve comprises a cylinder body, a first pipe joint arranged at the first end of the cylinder body, a second pipe joint arranged at the second end of the cylinder body, and a valve plate arranged in the cylinder body, wherein the first pipe joint is communicated with the cylinder body through a first connecting channel, the second pipe joint is communicated with the cylinder body through a second connecting channel, the top end of the valve plate is fixedly connected with the cylinder body, and the bottom end of the valve plate is movably arranged in the cylinder body and can seal and cover the first connecting channel.

In the auxiliary air inlet type smoke exhaust pipe of the balanced gas water heater, a cylindrical inclined table which can be matched with the valve plate is arranged at the joint of the cylinder body and the first pipe joint, the inclined table is communicated with the first connecting channel, and the inclined table gradually extends to the second end of the cylinder body from the top end to the bottom end.

In the auxiliary air inlet type smoke exhaust pipe of the balanced gas water heater, a first annular end plate fixedly connected with a first pipe joint is fixedly arranged at the first end of the cylinder, a second annular end plate fixedly connected with a second pipe joint is fixedly arranged at the second end of the cylinder, and the top end of the valve plate is fixedly connected with the first annular end plate.

In the auxiliary air inlet type smoke exhaust pipe of the balanced gas water heater, the valve plate is a flexible valve plate, the valve plate is provided with the counterweight part, one surface of the valve plate corresponding to the inclined table is provided with the silica gel sealing ring, and the counterweight part can drive the valve plate to seal and cover the first connecting channel under the action of self gravity.

The auxiliary air inlet type smoke exhaust pipe of the balanced gas water heater has the following beneficial effects: when the balanced gas water heater is used for assisting the air inlet type smoke exhaust pipe, waste gas generated after combustion can be discharged outdoors through the air exhaust inner pipe in the combustion process of the water heater, and meanwhile, outdoor air can be input into the water heater through the first air inlet channel between the air inlet outer pipe and the air exhaust inner pipe and the second air inlet channel in the auxiliary pipeline. Further, in cold weather, as the auxiliary pipeline is used as a branch pipe of the main pipeline and is far away from the exhaust inner pipe, cold/hot air alternation can not occur around the auxiliary pipeline, and condensed water and icing phenomena are not easy to occur on the peripheral wall of the auxiliary pipeline. When the main pipeline is condensed and frozen to cause that outdoor air cannot enter the water heater through the first air inlet channel, the outdoor air can enter the water heater through the second air inlet channel of the auxiliary pipeline, and the water heater can be used normally in cold weather.

Drawings

The utility model will be further described with reference to the accompanying drawings and examples, in which:

FIG. 1 is a schematic diagram of a first embodiment of an auxiliary intake type smoke exhaust pipe of a balanced gas water heater according to the present utility model;

FIG. 2 is a schematic diagram of a second embodiment of an auxiliary air intake type smoke exhaust pipe of the balanced gas water heater of the present utility model;

FIG. 3 is a schematic top view of a second embodiment of an auxiliary air intake type smoke exhaust pipe of the balanced gas water heater of the present utility model;

FIG. 4 is a schematic cross-sectional view of a main pipe in an auxiliary air intake type smoke exhaust pipe of the balanced gas water heater;

FIG. 5 is a schematic sectional view showing the opened state of a check valve in an auxiliary air intake type smoke exhaust pipe of the balanced type gas water heater.

Detailed Description

For the purpose of making the objects, technical solutions and advantages of the present utility model more apparent, the embodiments of the present utility model will be described in further detail with reference to the accompanying drawings.

As shown in fig. 1 to 4, in the first embodiment of the auxiliary intake type smoke exhaust pipe of the balance type gas water heater of the present utility model, the smoke exhaust pipe 10 includes a main pipe 11, and an auxiliary pipe 12 connected to and communicating with the main pipe 11.

The main pipe 11 includes an exhaust inner pipe 13 and an air inlet outer pipe 14 fixedly sleeved outside the exhaust inner pipe 13, an exhaust channel 15 is formed inside the exhaust inner pipe 13, a first air inlet channel 16 is formed between the outer wall of the exhaust inner pipe 13 and the inner wall of the air inlet outer pipe 14, and the exhaust inner pipe 13 and the air inlet outer pipe 14 both include an outdoor section 17 extending outdoors and an indoor section 18 connected with the water heater 100 and located indoors.

Wherein, a second air inlet pipe is formed inside the auxiliary pipe 12, a first end of the auxiliary pipe 12 is connected with the indoor section 18 of the air inlet outer pipe 14, and the second air inlet pipe is communicated with the first air inlet pipe, and a second end of the auxiliary pipe 12 can extend out of the room simultaneously with the outdoor section 17 of the air inlet outer pipe 14.

When the balanced gas water heater 100 is used for assisting the gas inlet type smoke exhaust pipe 10, waste gas generated after combustion can be discharged outdoors through the gas exhaust inner pipe 13 in the combustion process of the water heater 100, and meanwhile, outdoor air can be input into the water heater 100 through the first gas inlet channel 16 between the gas inlet outer pipe 14 and the gas exhaust inner pipe 13 and the second gas inlet channel in the auxiliary pipeline 12. Further, in cold weather, since the auxiliary duct 12 is a branch pipe of the main duct 11, which is far from the exhaust inner duct 13, the cold/hot air alternation around the auxiliary duct 12 does not occur, and condensed water and icing phenomenon are not easily occurred on the peripheral wall of the auxiliary duct 12. When condensation and icing occur in the main pipe 11 and outdoor air cannot enter the water heater 100 through the first air inlet channel 16, outdoor air can enter the water heater 100 through the second air inlet channel of the auxiliary pipe 12, so that the water heater 100 can be used normally in cold weather.

Specifically, the second end of the auxiliary duct 12 extends toward the outdoor section 17 of the outer intake duct 14 to form an outdoor-extendable extension 19, and the extension 19 of the auxiliary duct 12 is substantially parallel to the outdoor section 17 of the outer intake duct 14. It is understood that substantially parallel as referred to herein means that the angle between the two is equal to 0 ° or the angle is less than 10 °, or the angle between the two is equal to 0 ° or the angle is less than 15 °. Reference to substantially parallel in this application includes absolute parallel and near parallel. "substantially parallel" in the present utility model is preferably substantially parallel in the same horizontal plane.

In the present application, the outdoor section 17 of the main pipe 11 and the extension section 19 of the auxiliary pipe 12 are extended to the outside for discharging the exhaust gas generated by the combustion of the water heater 100 to the outside while sucking air from the outside for the combustion supporting of the water heater 100.

For the convenience of air intake and smoke exhaust, a first air intake hole 20 communicated with the first air intake channel 16 is arranged on the side wall of the outdoor section 17 of the air intake outer pipe 14, an air exhaust hole 22 communicated with the air exhaust inner pipe 13 is also arranged on the side wall of the outdoor section 17 of the air intake outer pipe 14, and a second air intake hole 21 communicated with the second air intake channel is arranged on the side wall of the extending section 19 of the auxiliary pipe 12.

Specifically, the exhaust hole 22 is closer to the second end of the intake outer tube 14 than the first intake hole 20, and the end of the exhaust inner tube 13 communicates with the exhaust hole 22 through a bent tube.

The first air intake hole 20, the air discharge hole 22 and the second air intake hole 21 are all located outdoors when the outdoor section 17 of the air intake outer pipe 14 and the extension section 19 of the auxiliary duct 12 are extended outdoors.

Preferably, the first air intake holes 20 and the second air intake holes 21 are in a mutually flush position.

As shown in fig. 1, in the first embodiment of the present application, the air intake outer pipe 14 includes at least a first straight pipe 23 connected to the water heater 100, a second straight pipe 24 different from the first straight pipe 23 in the longitudinal direction, and a first connecting pipe 25 connecting and communicating the first straight pipe 23 and the second straight pipe 24, and the outdoor section 17 of the air intake outer pipe 14 is located at the second end of the second straight pipe 24.

The auxiliary duct 12 includes a first tube body 36 and a second tube body 37 connected and communicating with each other, the first tube body 36 being fixedly connected and communicating with the indoor section of the second straight tube 24, the second tube body 37 being disposed substantially parallel to the second straight tube 24.

Preferably, the first straight tube 23 and the second straight tube 24 are disposed perpendicular to each other, and the connecting tube 25 is a bendable threaded C-shaped first connecting tube 25. It will be appreciated that the exhaust inner pipe 13, like the intake outer pipe 14, also includes two straight pipes and a connecting pipe connecting the two straight pipes, respectively.

In the present embodiment, the first tube 36 communicates with the indoor section 18 of the second straight tube 24, and the first tube 36, the second tube 37 and the second straight tube 24 are located on the same plane.

As shown in fig. 2 and 3, in the second embodiment of the present application, the air intake outer pipe 14 includes at least a third straight pipe 38 connected to the water heater 100, a fourth straight pipe 39 different from the third straight pipe 38 in the longitudinal direction, a fifth straight pipe 40 different from the fourth straight pipe 39 in the longitudinal direction, a second connecting pipe 41 connecting and communicating the third straight pipe 38 and the fourth straight pipe 39, and a third connecting pipe 42 connecting and communicating the fourth straight pipe 39 and the fifth straight pipe 40, and the outdoor section 17 of the air intake outer pipe 14 is located at the second end of the fifth straight pipe 40.

The first end of the auxiliary conduit 12 is fixedly connected to and communicates with the fourth straight conduit 39, and the auxiliary conduit 12 is disposed substantially parallel to the fifth straight conduit 40. In the present embodiment, the auxiliary pipe 12 is directly connected to the fourth straight pipe 39, and the fourth straight pipe 39, the fifth straight pipe 40 and the auxiliary pipe 12 are located on the same plane.

Preferably, the third straight tube 38 and the fourth straight tube 39 are disposed perpendicular to each other, the fourth straight tube 39 and the fifth straight tube 40 are disposed perpendicular to each other, and the second connection tube 41 and the third connection tube 42 are each a bendable threaded C-shaped connection tube.

Further, as shown in fig. 5, the auxiliary duct 12 is provided with a check valve 26 that allows only outdoor air to flow in one direction to the water heater 100. The check valve 26 allows only outdoor air to enter the water heater 100 through the auxiliary duct 12, restricting the reverse flow of air. In the present utility model, the check valve 26 is preferably provided in the room.

Specifically, the check valve 26 includes a cylinder 27, a first pipe joint 28 disposed at a first end of the cylinder 27, a second pipe joint 29 disposed at a second end of the cylinder 27, and a valve plate 32 disposed in the cylinder 27, where the first pipe joint 28 is communicated with the cylinder 27 through a first connecting channel 30, the second pipe joint 29 is communicated with the cylinder 27 through a second connecting channel 31, a top end of the valve plate 32 is fixedly connected with the cylinder 27, and a bottom end of the valve plate 32 is movably disposed in the cylinder 27 and can seal and cover the first connecting channel 30.

In order to achieve better unidirectional sealing effect, a cylindrical inclined table 43 capable of being matched with the valve plate 32 is arranged at the joint of the cylinder 27 and the first pipe joint 28, the inclined table 43 is communicated with the first connecting channel 28, and the inclined table 43 gradually extends from top to bottom to the second end of the cylinder 27.

By arranging the inclined table 43 in an inclined state, when the valve plate 32 moves downwards under the gravity of the valve plate, the valve plate can be better abutted with the surface of the inclined table 43, so that a better sealing effect is formed.

Further, a first annular end plate 33 fixedly connected with the first pipe joint 28 is fixedly arranged at a first end of the cylinder 27, a second annular end plate 34 fixedly connected with the second pipe joint 29 is fixedly arranged at a second end of the cylinder 27, and the top end of the valve plate 32 is fixedly connected with the first annular end plate 33.

During the intake process, the outdoor air enters through the first pipe joint 28, the first connecting passage 30 and pushes the valve to turn to open around the top thereof, and the air continues to flow into the water heater 100 along the cylinder 27, the second connecting passage 31 and the second pipe joint 29. When the gas flows reversely, the gas pushes the bottom end of the valve plate 32 to move toward the first annular end plate 33, and at this time, the valve plate 32 seals the first connecting passage 30 and forms a reverse seal.

Preferably, the valve sheet 32 is a flexible valve sheet 32. In order to better control the valve plate 32 to cover the first connecting channel 30 under the action of self gravity, the valve plate 32 is provided with a counterweight piece 35, one surface of the valve plate 32 corresponding to the inclined table 43 is provided with a silica gel sealing ring 44, and the counterweight piece 35 can drive the valve plate 32 to seal and cover the first connecting channel 30 under the action of self gravity.

In addition, in the present utility model, unless explicitly specified and limited otherwise, the terms "connected," "stacked," and the like are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally formed; can be directly connected or indirectly connected through an intermediate medium, and can be communicated with the inside of two elements or the interaction relationship of the two elements. The specific meaning of the above terms in the present utility model can be understood by those of ordinary skill in the art according to the specific circumstances.

The foregoing description is only illustrative of the present utility model and is not intended to limit the scope of the utility model, and all equivalent structures or equivalent processes or direct or indirect application in other related technical fields are included in the scope of the present utility model.

Claims

1. The auxiliary air inlet type smoke exhaust pipe of the balanced gas water heater is characterized in that the smoke exhaust pipe (10) comprises a main pipe (11) and an auxiliary pipe (12) which is connected and communicated with the main pipe (11);

the main pipeline (11) comprises an exhaust inner pipe (13) and an air inlet outer pipe (14) fixedly sleeved outside the exhaust inner pipe (13), an exhaust channel (15) is formed inside the exhaust inner pipe (13), a first air inlet channel (16) is formed between the outer wall of the exhaust inner pipe (13) and the inner wall of the air inlet outer pipe (14), and the exhaust inner pipe (13) and the air inlet outer pipe (14) both comprise an outdoor section (17) extending outdoors and an indoor section (18) connected with the water heater and located indoors;

a second air inlet pipeline is formed in the auxiliary pipeline (12), a first end of the auxiliary pipeline (12) is connected with an indoor section (18) of the air inlet outer pipe (14) and is communicated with the first air inlet pipeline, and a second end of the auxiliary pipeline (12) and an outdoor section (17) of the air inlet outer pipe (14) can extend outdoors at the same time;

the second end of the auxiliary pipeline (12) extends towards the outdoor section (17) of the air inlet outer pipe (14) to form an extension section (19) which can extend out of the room; the auxiliary pipeline (12) is provided with a one-way valve (26) which only allows outdoor air to flow to the water heater in one way.

2. Auxiliary inlet smoke exhaust pipe for a balanced gas water heater according to claim 1, characterized in that the protruding section (19) of the auxiliary pipe (12) is substantially parallel to the outdoor section (17) of the inlet outer pipe (14).

3. The auxiliary air inlet type smoke exhaust pipe of the balanced type gas water heater according to claim 2, wherein a first air inlet hole (20) communicated with the first air inlet channel (16) is formed in the side wall of an outdoor section (17) of the air inlet outer pipe (14), an air outlet hole (22) communicated with the air outlet inner pipe (13) is further formed in the side wall of the outdoor section (17) of the air inlet outer pipe (14), and a second air inlet hole (21) communicated with the second air inlet pipe is formed in the side wall of an extending section (19) of the auxiliary pipe (12).

4. The auxiliary intake smoke exhaust pipe of a balance type gas water heater according to claim 1, wherein the intake outer pipe (14) comprises at least a first straight pipe (23) connected with the water heater, a second straight pipe (24) different from the first straight pipe (23) in length direction, and a first connecting pipe (25) connecting and communicating the first straight pipe (23) and the second straight pipe (24), and the outdoor section (17) of the intake outer pipe (14) is positioned at the second end of the second straight pipe (24);

the auxiliary pipeline (12) comprises a first pipe body (36) and a second pipe body (37) which are connected and communicated with each other, the first pipe body (36) is fixedly connected and communicated with the indoor section of the second straight pipe (24), and the second pipe body (37) is basically parallel to the second straight pipe (24).

5. The auxiliary air inlet type smoke exhaust pipe of the balance type gas water heater according to claim 1, wherein,

the air inlet outer tube (14) at least comprises a third straight tube (38) connected with the water heater, a fourth straight tube (39) different from the third straight tube (38) in the length direction, a fifth straight tube (40) different from the fourth straight tube (39) in the length direction, a second connecting tube (41) connected with and communicated with the third straight tube (38) and the fourth straight tube (39), and a third connecting tube (42) connected with and communicated with the fourth straight tube (39) and the fifth straight tube (40), and the outdoor section (17) of the air inlet outer tube (14) is positioned at the second end of the fifth straight tube (40);

the first end of the auxiliary pipeline (12) is fixedly connected and communicated with the fourth straight pipe (39), and the auxiliary pipeline (12) and the fifth straight pipe (40) are arranged basically in parallel.

6. The auxiliary air inlet type smoke exhaust pipe of a balanced type gas water heater according to claim 5, wherein the one-way valve comprises a cylinder body (27), a first pipe joint (28) arranged at a first end of the cylinder body (27), a second pipe joint (29) arranged at a second end of the cylinder body (27), and a valve plate (32) arranged in the cylinder body (27), the first pipe joint (28) is communicated with the cylinder body (27) through a first connecting channel (30), the second pipe joint (29) is communicated with the cylinder body (27) through a second connecting channel (31), the top end of the valve plate (32) is fixedly connected with the cylinder body (27), and the bottom end of the valve plate (32) is movably arranged in the cylinder body (27) and can seal the first connecting channel (30).

7. The auxiliary air inlet type smoke exhaust pipe of the balanced type gas water heater according to claim 6, wherein a cylindrical inclined table (43) which can be matched with the valve plate (32) is arranged at the joint of the cylinder (27) and the first pipe joint (28), the inclined table (43) is communicated with the first pipe joint (28), and the inclined table (43) gradually extends from the top end to the bottom end to the second end of the cylinder (27).

8. The auxiliary air inlet type smoke exhaust pipe of the balanced type gas water heater according to claim 7, wherein a first annular end plate (33) fixedly connected with a first pipe joint (28) is fixedly arranged at the first end of the cylinder (27), a second annular end plate (34) fixedly connected with a second pipe joint (29) is fixedly arranged at the second end of the cylinder (27), and the top end of the valve plate (32) is fixedly connected with the first annular end plate (33).

9. The auxiliary air inlet type smoke exhaust pipe of the balanced type gas water heater according to claim 8, wherein the valve plate (32) is a flexible valve plate, a weight piece (35) is arranged on the valve plate (32), a silica gel sealing ring (44) is arranged on one surface of the valve plate (32) corresponding to the inclined table (43), and the weight piece (35) can drive the valve plate (32) to seal the cover of the first connecting channel (30) under the action of self gravity.