JP2000087799A - Piston having ceramic piston head for engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a ceramic piston head from being damaged during operation of an engine by abnormal surface pressure applied thereon or by free movement collision and to reduce costs of manufacturing parts for retaining the ceramic piston head on a metal piston body. SOLUTION: A head outer peripheral surface retaining material 11 is inserted between a head outer peripheral surface 8 of a ceramic piston head 3 and an inner peripheral surface 9 of a head housing 2. A head upper surface pressing material 13 is inserted between a peripheral upper surface 6 of the piston head 3 and a head retainer 7. The head outer peripheral surface retaining material 11 and the head upper surface pressing material 13 is formed of a material having a thermal expansion coefficient higher than a metal material of a piston body 1. The head outer peripheral surface retaining material 11 and the head upper surface pressing material 13 are made of a heat-resisting elastic material having voids over the entire thickness thereof.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piston with a ceramic piston head used for an engine such as a diesel engine, a gasoline engine, or a gas engine.

[0002]

[Assumption] A piston having a ceramic piston head for an engine according to the present invention is intended to have the following assumption as shown in FIG. 1 (present invention) or FIG. 9 (prior art). FIG. 1 shows a first embodiment of a piston with a ceramic piston head of an engine according to the present invention, wherein FIG. 1 (A) is a longitudinal sectional front view, and FIG. 1 (B) is a cutaway plan view of a main part. FIG. 9 is a longitudinal sectional front view of a piston with a ceramic piston head showing the prior art 1.

A head accommodating chamber (2) is formed in an upper wall portion of a metal piston body (1), and a ceramic piston head (3) is inserted into the head accommodating chamber (2). The lower surface of the piston head (3) on the bottom surface (4) of the head storage chamber (2)
(5) Make them accept. Metal head retainer that presses downward on the upper surface (6) of the head periphery of the piston head (3)
(7) is fixed to the piston body (1). Above piston body
Examples of the metal forming (1) include an aluminum alloy and cast iron.

[Operation of Premise Configuration] The combustion performance of the engine is enhanced, and the thermal efficiency is also enhanced. The gas that burns and expands in the combustion chamber of the engine is insulated by the ceramic piston head (3), thereby reducing heat loss. Therefore, the combustion performance of the engine is improved, and the thermal efficiency is also improved.

[0005] The cylinder can be made of metal which is inexpensive to manufacture. Since the metal piston body (1) matches well with the metal cylinder, the cylinder does not need to be made of expensive ceramics, and can be made of metal with low manufacturing cost.

[0006]

2. Description of the Related Art In the above-mentioned premise, there are the following prior arts for assembling a ceramic piston head to a metal piston main body. ○ Conventional technology 1. See FIG. (The actual opening 61-164
FIG. 9 is a longitudinal sectional front view of a piston with a ceramic piston head.

The outer peripheral surface (51) of the ceramic piston head (3) and the inner peripheral surface of the head storage chamber (2)
(52) is interviewed. A gap (53) is formed between the upper peripheral surface (6) of the piston head (3) and the head retainer (7). A seal ring (54) is interposed between the head upper surface (6) of the piston head (3) and the head retainer (7).

[0008]

In the prior art 1 described above,
There are the following problems. (I). When the engine is stopped or started, the piston head (3) made of ceramics is easily damaged due to abnormal surface pressure.
When the engine is stopped or started, the temperature of the piston is low, so the metal piston body (1) has a larger heat shrinkage than the ceramic piston head (3).
The contact surface pressure at which the inner peripheral surface (52) of the head housing chamber (2) of the piston main body (1) comes into contact with the head outer peripheral surface (51) of the piston head (3) tends to rise abnormally. The piston head (3) made of ceramics is liable to be damaged due to an abnormal increase in pressure.

(B). In the operating state of the engine, the piston head (3) made of ceramics easily breaks due to free collision with the piston body (1). In the operating state of the engine, since the temperature of the piston becomes high, the difference in thermal expansion between the metal piston body (1) and the ceramic piston head (3) increases, and the outer peripheral surface of the piston head (3) is increased.
(51) and the outer peripheral surface (5) of the head housing chamber (2) of the piston body (1).
A gap (53) is formed between the upper surface (6) of the head periphery of the piston head (3) and the head retainer (7).
Becomes larger.

For this reason, the piston head (3) floats back and forth, right and left and up and down in the head accommodating chamber (2) of the piston body (1) by vibrating force due to the reciprocating motion of the piston. ) And the head retainer (7), and the floating collision cannot be suppressed by the seal ring (54), so that the piston head (3) is easily damaged by the floating collision.

An object of the present invention is to make the following. (I). When the engine is stopped or started, the piston head made of ceramics is prevented from being damaged due to abnormal surface pressure or free running collision. (B). In the operating state of the engine, it is possible to prevent the piston head made of ceramics from being damaged due to abnormal surface pressure or free running collision.

(C). The processing cost of parts for holding the ceramic piston head on the metal piston body is reduced. (D). The piston head can be easily assembled to the piston body. (E). Even when the engine is running at a high rotation speed and a high load, the piston head is strongly prevented from being damaged by a floating collision.

[0013]

The piston with a ceramic piston head according to the present invention has a structure for assembling a ceramic piston head to a metal piston body in order to solve the above-mentioned problems. As shown in FIGS. 1 to 8, the following feature configuration is added.

○ Invention 1. Claim 1. 1 and 2,
See FIG. 3 to FIG. 6 and FIG. FIG. 1 shows a first embodiment of a piston with a ceramic piston head of an engine according to the present invention, wherein FIG. 1 (A) is a longitudinal sectional front view, and FIG. 1 (B) is a cutaway plan view of a main part. FIG. 2 shows FIG.
(A) Part II enlarged view. FIGS. 3 to 6 are longitudinal sectional front views of main parts taken out, showing modifications of the head holding fixing means according to the first embodiment. FIG. 8 is a cross-sectional plan view of a piston, corresponding to a cross section taken along line VIII-VIII of FIG. 1A, showing Embodiment 3 of the present invention.

The outer peripheral surface (8) of the ceramic piston head (3) and the inner peripheral surface of the head accommodating chamber (2).
A holding material accommodating gap (10) is formed with (9), and the head outer peripheral surface holding material (11) is inserted into the holding material accommodating gap (10). A pressing material accommodating gap (12) is formed between the peripheral upper surface (6) of the piston head (3) and the head retainer (7), and the head upper surface pressing material (13) is inserted into the pressing material accommodating gap (12). insert. The head outer peripheral surface holding member (11) and the head upper surface pressing member (13) are characterized by being formed of a material having a larger thermal expansion coefficient than the metal material forming the piston body (1).

As a specific material of the head outer peripheral surface holding member (11) and the head upper surface pressing member (13), for example, "Interram" sold by Sumitomo 3M Limited is used.
(Trademark). The “Interram” is formed as a steel wool or a non-woven fabric, and is sold as a heat-resistant elastic material having voids throughout its thickness. The head outer peripheral surface holding material (11) and the head upper surface pressing material (13) of the constituent elements of the present invention have a gap over the entire thickness within the thickness of the “Interram” sold. There are cases where the "interram" is used as being made of a heat-resistant elastic material, and when the "interram" is used after being remodeled into a solid shape having no void in its thickness.

○ Invention 2. Claim 2. See FIG. FIG. 7 is a vertical sectional front view showing a main part of a piston according to a second embodiment of the present invention. In the configuration of the piston with a ceramic piston head of the engine according to the first aspect of the invention, the head housing chamber (2) is formed inside a metal cylindrical frame (14) instead of being formed in the upper wall portion of the piston body (1). Form in space. The lower part of the cylinder (14) is fixed to the upper wall of the piston body (1) by fixing means (15), and the head retainer (7) is fixed to the upper part of the cylinder of the cylinder frame (14). Features.

○ Invention 3. Claim 3. The following structure is added to the structure of the piston with a ceramic piston head of the engine according to the invention 1 or 2 described above. The head outer peripheral surface holding material
(11) and the head upper surface pressing member (13) are characterized by being made of a heat-resistant elastic material having a void over the entire area within its thickness.

○ Invention 4. The following configuration is added to the configuration of the piston with the ceramic piston head of the engine according to the invention 1, 2 or 3 described above. The head outer peripheral surface holding member (11) and the head upper surface are larger than the increasing ratio of the gap width of the holding material accommodating gap (10) and the pressing material accommodating gap (12) caused by the temperature rise of the piston due to the operation of the engine. The solid portion of the heat-resistant elastic material of the pressing member (13) has a larger thermal expansion ratio than the solid portion.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a piston with a ceramic piston head of an engine according to the present invention will be described below.
This will be described with reference to the drawings.

Embodiment 1 Claims 1, 3, and 4.
See FIG. 1 and FIG. FIG. 1 shows a first embodiment of a piston with a ceramic piston head of a direct injection diesel engine according to the present invention, in which FIG. 1 (A) is a longitudinal sectional front view, and FIG. 1 (B) is a cutaway plan view of a main part. FIG. 2 is an enlarged view of a portion II in FIG.

1 and 2, reference numeral (1) denotes a piston body (1) of a direct injection diesel engine, which is made of an aluminum alloy or cast iron. A head accommodating chamber (2) is formed in the upper wall portion of the piston body (1) so as to penetrate vertically. A piston head (3) made of ceramics is inserted into the head storage chamber (2). A reentrant combustion chamber (21) is formed in the piston head (3).

The lower surface (5) of the piston head (3) is received on the chamber bottom surface (4) of the head storage chamber (2). An annular head retainer (7) for pressing the upper surface (6) of the head peripheral portion of the piston head (3) downward is fixed to the piston body (1) with eight rivets (22). The head retainer (7) is made of an aluminum alloy or cast iron of the same material as the piston body (1). The rivet (22) is integrally formed upward from the piston body (1).

The outer peripheral surface (8) of the ceramic piston head (3) and the inner peripheral surface of the head housing chamber (2)
A holding material accommodating gap (10) is formed with (9). A cylindrical head outer peripheral surface holding material (11) is inserted into the holding material accommodation gap (10). A pressing material accommodating gap (12) is formed between the upper peripheral surface (6) of the piston head (3) and the head retainer (7). An annular plate-shaped head upper surface pressing material (13) is inserted into the pressing material accommodation gap (12).
Insert The head outer peripheral surface holding member (11) and the head upper surface pressing member (13) are formed of a material having a larger coefficient of thermal expansion than the metal material forming the piston body (1).

The head outer peripheral surface holding member (11) and the head upper surface pressing member (13) are made of a heat-resistant elastic material having a void throughout the entire thickness thereof.
There is "Interram" (trademark) sold by Sumitomo 3M Limited. The “Interram” is sold in the form of a heat-resistant elastic material formed in a steel wool shape or a nonwoven fabric shape and having voids throughout its thickness.

The head outer peripheral surface holding member (11) is larger than the increase rate of each of the holding material housing gap (10) and the pressing material housing gap (12) caused by the rise in the temperature of the piston due to the operation of the engine. In addition, the thermal expansion ratio of each solid portion made of the heat-resistant elastic material of the head upper surface pressing member (13) is configured to be larger.

A modified example of the first embodiment. In the configuration of the first embodiment, a rivet is used as a configuration for fixing the head retainer (7) to the piston body (1).
Modification 1 in which the following items are used instead of using (22)
-5 is conceivable. Each of FIGS. 3 to 6 is a vertical sectional front view of a main part taking out showing a modified example 1-4 of the head holding fixing means.

Modification 1 See Fig. 3 Head retainer (7) is attached to piston body (1) with eight bolts.
Secure with (23). ○ Modification 2. Referring to FIG. 4, the cylindrical portion (24) is integrally protruded upward from the piston body (1) as shown by a virtual line. The cylindrical portion (24) is bent in a horizontal annular shape toward the head accommodating chamber (2) to form a head retainer (7).

O Modification 3 Refer to Fig. 5. The head holder (7) is connected to the upper cylindrical part (25) of the piston body (1).
The inside is fixed by screw fitting (26). ○ Modification 4. Referring to FIG. 6, the inner screw cylinder (27) is integrally extended downward from the outer periphery of the head retainer (7). Insert this inner screw cylinder (27) into the piston body
It is fixed to the outer peripheral surface of the upper cylindrical portion (28) of (1) by screw fitting (29). ○ Modification 5. The illustration is omitted. The reentrant combustion chamber (21) is omitted from the ceramic piston head (3), and the upper surface of the piston head (3) is formed flat.

◎ Embodiment 2 Claim 2 (3.4). FIG. 7 is a longitudinal sectional front view of a main part of a piston according to a second embodiment of the present invention. In the configuration of the piston with the ceramic piston head of the engine according to the first embodiment (FIGS. 1 and 2), the head storage chamber (2) is formed instead of being formed in the upper wall of the piston body (1). Made of the same metallic material as the piston body (1) (aluminum alloy or cast iron)
Formed in the inner space of the cylindrical frame (14).

The cylindrical frame (14) is made of the same metal material (aluminum alloy or cast iron) as the piston body (1) and the head retainer (7). The lower part of the cylinder (14) is fixed to the upper wall of the piston body (1) by screw fitting (15), and the head retainer (7) is integrally formed on the upper part of the cylinder of the cylinder frame (14). I do. The reentrant combustion chamber (21) is omitted from the ceramic piston head (3), and the upper surface of the piston head (3) is formed flat.

[Embodiment 3] Claim 1 (3.4). FIG. 8 shows a third embodiment of the present invention, and FIG. 1 (A) VIII-VI.
FIG. 2 is a cross-sectional plan view of the piston corresponding to a cross section taken along line II. In the structure of the piston with a ceramic piston head of the engine described in the first embodiment (FIGS. 1 and 2), a part thereof is changed as follows. The head outer peripheral surface holding material
(11) and the head upper surface pressing member (13) are formed in four arcs, respectively, and are divided into four equally spaced portions in the circumferential direction in the holding material housing gap (10) and the pressing material housing gap (12). These are arranged in a dispersed manner.

[0033]

The piston with a piston head made of ceramic according to the present invention has the following effects. ○ Invention 1. Claim 1. 1 and 2, FIGS. 3 to 6,
See FIG. (I). When the engine is stopped or started, the piston head (3) made of ceramics is prevented from being damaged due to abnormal surface pressure or free running collision.

The outer peripheral surface (8) of the ceramic piston head (3) and the inner peripheral surface of the head accommodating chamber (2)
A holding material accommodating gap (10) is formed with (9), and the head outer peripheral surface holding material (11) is inserted into the holding material accommodating gap (10). A pressing material accommodating gap (12) is formed between the peripheral upper surface (6) of the piston head (3) and the head retainer (7), and the head upper surface pressing material (13) is inserted into the pressing material accommodating gap (12). insert. The head outer peripheral surface holding member (11) and the head upper surface pressing member (13) are formed of a material having a larger coefficient of thermal expansion than the metal material forming the piston body (1).

With this configuration, when the engine is stopped or started, the temperature of the piston is low, so that the difference in thermal expansion between the metal piston body (1) and the ceramic piston head (3) is small, and the holding material accommodating gap is small. (10) and the gap width of the pressing material accommodating gap (12) are small. Correspondingly, the head outer peripheral surface holding member (11) and the head upper surface pressing member (1
In 3), the amount of thermal expansion is small and the wall thickness is thin.

For this reason, with respect to the gap width of the holding material accommodating gap (10) and the pressing material accommodating gap (12), the head outer peripheral surface holding material
(11) and the head upper surface pressing member (13) are kept at appropriate thickness without becoming too thin or too thick. As a result, the ceramic piston head (3) is pressed against the metal piston body (1) with an appropriate surface pressure by the head outer peripheral surface holding material (11) and the head upper surface pressing material (13) having an appropriate thickness. Since it is held, it is possible to prevent damage due to abnormal surface pressure or loose collision.

(B). In the operating state of the engine, the piston head (3) made of ceramics is prevented from being damaged due to abnormal surface pressure or free running collision.

In the operating state of the engine, since the temperature of the piston becomes high, the difference in thermal expansion between the metal piston body (1) and the ceramic piston head (3) increases, and the holding material accommodating gap (10) and The gap width of the pressing material accommodation gap (12) is large. Correspondingly, the head outer peripheral surface holding member (11) and the head upper surface pressing member (13) have a large thermal expansion and a large thickness. Also, as the engine speed and load increase, the holding material accommodation gap (10)
And the gap width of the pressing material accommodating gap (12) further increases. Correspondingly, the thickness of the head outer peripheral surface holding member (11) and the head upper surface pressing member (13) are further increased.

For this reason, with respect to the gap width of the holding material accommodating gap (10) and the pressing material accommodating gap (12), the head outer peripheral surface holding material
(11) and the head upper surface pressing member (13) are kept at appropriate thickness without becoming too thin or too thick. As a result, the ceramic piston head (3) moves with respect to the metal piston body (1) and the head retainer (7).
Since the head outer surface holding material (11) and the head upper surface pressing material (13) with the appropriate thickness are held at the appropriate surface pressure, damage due to abnormal surface pressure or free running collision is eliminated. be able to.

○ Invention 2. Claim 2. See FIG. In the configuration of the piston with the ceramic piston head of the engine according to the first aspect, the head storage chamber (2)
Instead of being formed in the upper wall of the piston body (1),
It is formed in the internal space of the metal tubular frame (14). This cylinder frame (14)
Is fixed to the upper wall of the piston body (1) by fixing means (15), and the head retainer (7) is fixed to the upper part of the cylinder of the cylinder frame (14). Also, in this configuration, the effects (a) and (b) of the first invention can be exhibited in the same manner.

○ Invention 3. Claim 3. (C). The processing cost of the head outer peripheral surface holding material (11) and the head upper surface pressing material (13) can be reduced by the elastic deformation. The head outer peripheral surface holding member (11) and the head upper surface pressing member (13) were made of a heat-resistant elastic material having a void over the entire area within the thickness. From this configuration, the head outer peripheral surface holding material
(11) and the head upper surface pressing member (13) have the outer diameter / inner diameter and thickness of the ceramic piston head (3) as much as they can be elastically deformed in order to impart a clamping force at a predetermined surface pressure to the ceramic piston head (3). The allowable dimensional error can be significantly increased, and the processing cost can be reduced.

(D). The head outer peripheral surface holding member (11) and the head upper surface pressing member (13) can easily assemble the piston head (3) to the piston body (1) as much as the elastic deformation is possible. Head upper surface pressing material (1
In the case of 3), when the ceramic piston head 3 is provided with a clamping force at a predetermined surface pressure, the elasticity of the piston head 3 is increased by elastic deformation, and the piston head 3 can be easily assembled to the piston body 1.

○ Invention 4. Claim 4. (E). Even when the engine is running at a high rotational speed and a high load, the piston head (3) has a large oscillating force and a large pinching elastic pressure, so that damage due to free running collision can be strongly prevented. The head outer peripheral surface holding member (11) and the head upper surface are larger than the increasing ratio of the gap width of the holding material accommodating gap (10) and the pressing material accommodating gap (12) caused by the temperature rise of the piston due to the operation of the engine. The thermal expansion ratio of each solid portion made of the heat-resistant elastic material of the pressing member (13) was configured to be larger.

According to this configuration, as the operation of the engine becomes higher in rotational speed and load, the exciting force of the piston head (3) increases. On the other hand, the holding material accommodating gap (10) and the pressing material accommodating gap (12), which occur with a rise in the temperature of the piston.
Than the increase rate of each gap width of the head outer peripheral surface holding material (11)
The head outer peripheral surface holding member (11) and the head upper surface pressing member (13) are the same as the thermal expansion ratio of the heat resistant elastic material solid portion of the head upper surface pressing member (13) is larger. The elastic pressure holding (3) increases. For this reason, the piston head (3) has a large exciting force,
Since the pinching pressure is also increased, breakage due to floating collision can be strongly prevented.

[Brief description of the drawings]

FIG. 1 shows a first embodiment of a piston with a ceramic piston head of the present invention. FIG. 1 (A) is a longitudinal front view,
FIG. 1B is a plan view of a main part cutout.

FIG. 2 is an enlarged view of a part II in FIG.

FIG. 3 is a vertical cross-sectional front view of a main part taking out example showing Modification Example 1 of a head holding fixing means in the first embodiment.

FIG. 4 is a vertical cross-sectional front view of a main part removal showing a second modification of the head retainer fixing means in the first embodiment.

FIG. 5 is a vertical sectional front view of a main portion showing a modification 3 of the head holding fixing means in the first embodiment. .

FIG. 6 is a vertical cross-sectional front view of a main part taking-out example showing Modification Example 4 of the head holding fixing means in the first embodiment.

FIG. 7 is a vertical sectional front view of a main part of a piston according to a second embodiment of the present invention.

FIG. 8 shows Embodiment 3 of the present invention, and FIG.
FIG. 8 is a cross-sectional plan view of the piston corresponding to a cross section taken along line VIII.

FIG. 9 is a longitudinal sectional front view of a piston with a ceramic piston head, showing prior art 1;

[Explanation of symbols]

1. Metallic piston body. 2 ... Head accommodation room. 3
... Ceramic piston head. 4… Room bottom.
5 ... Head lower surface. 6: Top surface of head periphery. 7 ... Head holder made of metal. 8. Head outer peripheral surface. 9 ... indoor peripheral surface. 9: Holding material accommodation gap. 11 ... Head outer peripheral surface holding material. 12 ... Pressing material accommodation gap. 13 ... Head upper surface pressing material. 14 ... Metal tube frame. 15: Fixing means on upper wall.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification FI FI Theme Court ゛ (Reference) F16J 1/01 F16J 1/01 (72) Inventor Hirofumi Sekino 1-1-1 Hama, Amagasaki-shi, Hyogo Co., Ltd. Kubota Technology Research Institute (72) Inventor Tadao Yamato 1-1-1 Hama, Amagasaki-shi, Hyogo Prefecture Kubota Technology Research Institute Co., Ltd. F-term (reference) 3J044 AA01 AA08 BA05 CA03 CA18 CA40 DA09

Claims (4)

[Claims] 1. A head housing chamber (2) is formed in an upper wall portion of a metal piston body (1), and a ceramic piston head (3) is inserted into the head housing chamber (2) to house the head. The lower surface of the piston head (3) on the bottom surface (4) of the chamber (2)
(5) A metal head retainer (7) for receiving the piston head and pressing the upper surface (6) of the piston head (3) downward.
Is fixed to the piston body (1), and the piston with ceramic piston head of the engine is constituted, wherein the outer peripheral surface of the head of the ceramic piston head (3) is provided.
A holding material accommodating gap (10) is formed between (8) and the inner peripheral surface (9) of the head accommodating chamber (2), and the head outer peripheral surface holding material (11) is formed in the holding material accommodating gap (10). Insert the upper surface (6) of the piston head (3) and the head retainer (7).
A pressing material housing gap (12) is formed between the head outer surface holding material (11) and the head upper surface pressing material (13). 1
3) A piston with a ceramic piston head for an engine, wherein the piston is made of a material having a larger thermal expansion coefficient than a metal material forming the piston body (1). 2. A piston having a piston head made of ceramics for an engine according to claim 1, wherein the head accommodating chamber (2) is made of metal instead of being formed in the upper wall of the piston body (1). The lower part of the cylinder (14) is fixed to the upper wall of the piston body (1) by fixing means (15), and the upper part of the cylinder (14) is formed. A piston with a ceramic piston head for an engine, wherein the head retainer (7) is fixedly mounted on the piston. 3. The head outer peripheral surface holding member (11) and the head upper surface pressing member (13) are made of a heat-resistant elastic material having a void throughout the entire thickness thereof. 3. A piston with a ceramic piston head for the engine according to 1 or 2. 4. The head outer peripheral surface holding member (10) is higher than the increase rate of each of the holding member housing gap (10) and the pressing material housing gap (12) caused by the temperature rise of the piston due to the operation of the engine. 4. The method according to claim 1, wherein the thermal expansion ratio of each of the heat-resistant elastic material solid portions of the head pressing member and the head upper surface pressing member has a larger value. Piston with ceramic piston head for engine.