WO2008016010A1 - Piston ring - Google Patents

Abstract

Disclosed is a piston ring which can vary a tension under low-temperature and low-load conditions and a tension under high-temperature and high-load conditions, and therefore can minimize the friction loss and improve the fuel efficiency. The piston ring is formed by a titanium-tantalum shape memory alloy comprising tantalum in an amount of not less than 30 mol% and less than 40 mol%, with the remainder being titanium and unavoidable impurities.

Description

 Specification

 piston ring

 Technical field

 [0001] The present invention relates to a piston ring. More specifically, the present invention relates to a variable tension piston ring that is disposed in a piston ring groove of a piston in an internal combustion engine used for an automobile, a lawn mower, a generator, etc., and in which the tension in a high temperature state is increased compared to the tension in a low temperature state. .

 Background art

 [0002] Piston rings are roughly classified into two types: pressure rings and oil rings. In either case, the piston ring is composed of only one piston ring, the piston ring body, and this piston ring. There may be a case where an expander is disposed on the inner peripheral surface side of the main body to apply a pressing force in the direction of expanding the piston ring main body.

 [0003] The tension in such a piston ring is usually set so that the piston ring can perform its function even under the most severe conditions in which the piston ring can be used. For example, in a piston ring attached to a piston of an internal combustion engine (engine), the tension of the piston ring is set assuming a high speed and high load state of the internal combustion engine. Specifically, even when the piston ring is composed of only one piston ring, the tension of the piston ring itself is designed assuming a high speed and high load state. Alternatively, even when the piston ring is composed of a piston ring main body and an expander, the sum of the tension of the piston ring main body and the expander is similarly designed assuming a high speed and high load state.

 [0004] Here, in recent years, in order to aim for an engine that is environmentally friendly and particularly low in fuel consumption, there is an increasing demand for reducing friction between the piston ring and the cylinder liner.

[0005] However, in the conventional piston ring, as the speed of the reciprocating motion of the piston increases due to the increase in the number of revolutions of the engine when sliding along the cylinder inner peripheral surface together with the piston, the cylinder inner peripheral surface and the piston ring The force that lifts the piston ring (fluttering) due to the sliding friction and the piston's inertial force increases, and the oil consumption tends to increase at higher speeds and loads. Therefore, high-speed and high-load conditions, ie internal combustion engines Since the tension of the entire piston ring is set assuming that the piston is at a high temperature, excessive tension is not applied to the cylinder's inner surface in a low-speed, low-load state, that is, when the internal combustion engine is at a low temperature. As a result, a lot of friction loss occurred. In addition, it is possible to set the tension of the entire piston ring in a low-speed and low-load state.If high-speed and high-load operation is performed, the piston ring cannot be sufficiently sealed and the oil consumption increases rapidly. This is not preferable.

[0006] In order to solve such a problem, a piston ring has been developed that can change the tension of the piston ring between a low temperature and a high temperature by forming the piston ring from a shape memory alloy.

 [0007] Specifically, for example, in Patent Document 1, in a piston ring composed of only one piston ring, the piston ring is formed of a nickel-titanium-based shape memory alloy. A technique is disclosed in which the piston ring and the cylinder inner peripheral surface are brought into non-contact and the piston ring and the cylinder inner peripheral surface are brought into contact with each other only when a high temperature is reached! (See paragraphs, etc.)

 [0008] In Patent Document 2, in the piston ring composed of a piston ring main body and an expander (coil expander), the expander is formed of a nickel titanium-based shape memory alloy as in Patent Document 1. By doing so, a technique for increasing the tension in the high temperature state than the tension in the low temperature state is disclosed (see the claims of the utility model registration in Patent Document 2).

 [0009] As described above, the use of a shape memory alloy as a material for the piston ring has been conventionally performed.

 [0010] Here, as a shape memory alloy, for example, Patent Document 3 discloses a shape memory alloy characterized by adding palladium to nickel-titanium for the purpose of transformation at a higher temperature.

 [0011] Further, Patent Document 4 discloses a shape memory alloy characterized by adding zirconium (or hafnium) to nickel titanium for the same purpose as Patent Document 3.

[0012] Furthermore, Patent Document 5 discloses a shape with a wide range of transformation temperatures and excellent workability. In order to provide a memory alloy, a shape memory alloy characterized by adding niobium to nickel titanium is disclosed.

 Patent Document 1: Japanese Patent Laid-Open No. 06-0666371

 Patent Document 2: Actual Fairness No. 03-041078

 Patent Document 3: Japanese Patent Laid-Open No. 11 036024

 Patent Document 4: Japanese Patent Laid-Open No. 10-008168

 Patent Document 5: Japanese Patent Application Laid-Open No. 61-119639

 Disclosure of the invention

 Problems to be solved by the invention

[0013] However, the current piston ring does not completely solve the problem of friction loss, and needs to be improved to further improve fuel consumption.

Specifically, the piston ring disclosed in Patent Document 1 cannot be applied in a temperature range of 80 ° C. or higher with a force S in which a nickel-titanium alloy is used as a shape memory alloy. The effect cannot be expected in an automobile engine or the like that is subjected to severe temperature conditions.

[0015] Even in the piston ring disclosed in Patent Document 2, the same shape memory alloy as in Patent Document 1 is used, so that it can be used in a temperature range of 80 ° C or higher. It is unsuitable for use and cannot be expected to improve fuel efficiency.

[0016] Further, in the shape memory alloy disclosed in Patent Document 3, since expensive palladium is used as an additive, the material cost is remarkably increased and the workability is inferior, so that it is applied to piston rings. It is difficult.

[0017] Also, the shape memory alloy disclosed in Patent Document 4 is difficult to apply to piston rings because of poor workability.

[0018] In addition, the shape memory alloy disclosed in Patent Document 5 has not been put into practical use because it has poor structural stability and loses its shape memory characteristics.

[0019] The present invention has been made in view of such a situation, and the tension in the low temperature state and the tension in the high temperature state can be changed within the practical range of the engine, and as a result, the flexion loss is minimized. The main issue is to provide a piston ring that can reduce fuel consumption and improve fuel efficiency. Means for solving the problem

[0020] The first piston ring of the present invention for solving the above-mentioned problems is 30 mol% or more 40mol

It is characterized by being formed of a titanium tantalum shape memory alloy composed of less than% tantalum, the balance of titanium, and inevitable impurities.

[0021] In addition, the second piston ring of the present invention includes 25 mol% or more and 30 mol% or less of tantalum, lmol% or more and 5 mol% or less of α-phase stabilizing element, the remaining titanium, and inevitable impurities.

It is characterized by being formed of a powerful titanium tantalum shape memory alloy.

[0022] Further, the third piston ring of the present invention comprises 25 mol% or more and 30 mol% or less of tantalum,

It is characterized by being formed of a titanium tantalum shape memory alloy composed of an interstitial element of 0.1 mol% or more and 1 mol% or less, the balance of titanium, inevitable impurities, and force.

[0023] Further, the fourth piston ring of the present invention is inevitable that 20 mol% or more and 30 mol% or less of tantalum, and lmol% or more and 10 mol% or less of tantalum (a three-phase stabilizing element and the remaining titanium). It is characterized by the fact that it is formed by a mechanical impurity and a powerful titanium-tantalum-based shape memory alloy.

 [0024] Further, the fifth piston ring of the present invention has a tantalum of 25 mol% or more and 30 mol% or less, a transition metal element of 0.5 mol% or more and 2 mol% or less, the remaining titanium, unavoidable impurities, force The titanium is formed of a tantalum-based shape memory alloy! /.

 [0025] Further, the sixth piston ring of the present invention is a titanium comprising 25 mol% or more and 30 mol% or less of tantalum, lmol% or more and 10 mol% or less of zirconium, the balance of titanium, unavoidable impurities, force. It is formed of a tantalum-based shape memory alloy.

 [0026] The seventh piston ring of the present invention is a titanium tantalum comprising 25 mol% or more and 30 mol% or less of tantalum, lmol% or more and 5 mol% or less of tin, the remaining titanium, and inevitable impurities. It is formed of a system shape memory alloy.

 [0027] Further, the eighth piston ring of the present invention comprises 20 mol% or more and 30 mol% or less of tantalum, an additive element added so that the total tantalum equivalent is 30 mol% or more and 39.5 mol% or less, and the balance It is formed of titanium, unavoidable impurities, and force, and is formed of titanium tantalum shape memory alloy.

[0028] In the eighth piston ring of the present invention, the additive element force α-phase stabilization An element, an interstitial element, a / 3-phase stabilizing element, and a transition metal element.

 [0029] Further, in the eighth piston ring of the present invention, the additive element includes zirconium of 1 mol% or more and 5 mol% or less, an α-phase stabilizing element, an interstitial element, and a / 3-phase stabilizing. And at least one element selected from the group consisting of elements and transition metal elements.

 [0030] Also, in the eighth piston ring of the present invention, the additive element is tin of lmol% or more and 2mol% or less, an α-phase stabilizing element, an interstitial element, and a / 3-phase stabilizing It has at least one kind of element and transition metal element.

 [0031] Further, the piston ring of the present invention includes a piston ring main body and an expander disposed on the inner peripheral surface side of the piston ring main body. The piston ring main body and the expander Both or any one of them may be formed of the shape memory alloy.

 [0032] In the piston ring of the present invention, the expander may be either a coil expander or a plate expander.

 [0033] In the piston ring of the present invention, the piston ring includes a side rail and a spacer expander, and either or both of the side rail and the spacer expander are used. One is made of the shape memory alloy! /

Yes

 [0034] Further, in the piston ring of the present invention, the tension at a temperature lower than the reverse transformation peak temperature of the shape memory alloy is 0.;! To 25Ν, and the reverse transformation peak temperature of the shape memory alloy It is preferable that the tension at the above temperature is 0.2 to 55 mm.

 [0035] The piston ring of the present invention may be used as an oil ring or a pressure ring.

 The invention's effect

[0036] According to the piston ring of the present invention, it is formed by the above-mentioned titanium tantalum-based shape memory alloy! /, So that it has a high temperature of 80 ° C or higher! /, Transformation temperature (transformation peak temperature (M *)) Or reverse transformation peak temperature (A *)) can be realized. Therefore, in low temperature and low load conditions, it will exhibit an appropriate low tension, but will transform when it reaches a high temperature and high load condition of 80 ° C or higher. Therefore, it is possible to provide a piston ring that can exert higher tension than a low temperature and low load state. As a result, friction loss in a low temperature and low load state can be minimized, and fuel consumption can be improved.

[0037] Further, a titanium tantalum-based shape memory alloy having such a component composition has a transformation strain (ε).

 Μ

 In addition, since the recovery strain (ε) is small and the recovery rate is high, it can withstand repeated use at high temperatures.

 A

 Therefore, the durability of the piston ring formed of the shape memory alloy is also improved.

[0038] Furthermore, a shape memory alloy having such a component composition is excellent in workability because it has a higher rolling ratio in cold working than a conventional shape memory alloy. Therefore, the desired shape

[0039] Furthermore, in the piston ring of the present invention, there is no problem even if the piston ring is composed of a piston ring main body and an expander arranged on the inner peripheral surface side of the piston ring main body. If at least one of the main body and the expander is formed of the shape-memory alloy, the same effect as described above can be obtained, and the expander can be either a coil expander or a plate expander. It is the same even if it is.

 [0040] The piston ring according to the present invention includes a side rail and a spacer expander, and both or one of the side rail and the spacer expander is the above-mentioned. Even if it is made of shape memory alloy! /, The same effect can be obtained with force S.

 [0041] Further, in the piston ring of the present invention, the tension at a temperature lower than the reverse transformation peak temperature of the shape memory alloy (temperature assuming starting of the engine: 30 to 50 ° C) is 0. 1 to 25N, and the tension at the temperature higher than the reverse transformation peak temperature of the shape memory alloy (temperature assuming high speed rotation after the engine starts, temperature after austenite transformation) is in the range of 0.2 to 55N By setting the inside, it is possible to serve as a piston ring even in a high temperature and high load state while minimizing friction loss in a low temperature and low load state.

 [0042] Note that the piston ring of the present invention can exhibit the above-described effects even if it is used as either an oil ring or a pressure ring.

Brief Description of Drawings [0043] FIG. 1 is an explanatory diagram of a shape memory characteristic evaluation test. FIG. 1A is an explanatory diagram of a typical strain temperature curve of an alloy showing a repeated shape memory characteristic, and FIG. 1B is a repeated shape memory characteristic. FIG. 3 is an explanatory diagram of a typical strain temperature curve of an alloy.

 [Fig. 2] Explanatory diagram of experimental results of Ti Ta binary alloy of the material example of the present invention. Fig. 2A is an explanatory diagram of the relationship between the molar fraction of Ta and the transformation start temperature (Ms) under 50MPa. FIG. 2B is an explanatory diagram of strain temperature curves of Ti 32 Ta and Ti-40Ta.

 FIG. 3 is an explanatory diagram of a strain temperature curve of a Ti 27Ta binary alloy of the material example of the present invention.

 FIG. 4 is an explanatory diagram of a strain temperature curve of a Ti 22Nb binary alloy as a comparative material example.

 FIG. 5 is a schematic sectional view of an example of the piston ring of the present invention.

 FIG. 6 is a schematic cross-sectional view showing another example of the piston ring of the present invention, and FIG. 6 (a) is a schematic cross-section of a piston ring 40 composed of a piston ring main body 41, a coil expander 42, and a force. FIG. 6B is a schematic cross-sectional view of the piston ring 50 including the piston ring main body 51 and the plate expander 52. 6 (c) to (e) are schematic cross-sectional views of the side rings 44, 61, 71 and the spacer rings 45, 62, 72, and the piston rings 43, 60, 70 composed of forces. It is.

 Explanation of symbols

[0044] 30, 40, 43, 50, 60, 70 Piston ring

 41, 51 Piston ring body

 42 Coinole Expander

 44, 61, 71

 45, 62, 72 Spacer expander

 52 plate expander

 BEST MODE FOR CARRYING OUT THE INVENTION

[0045] The piston ring of the present invention will be specifically described below.

[0046] The piston ring of the present invention includes

 (1) 30 mol% or more and less than 40 mol% tantalum, the balance of titanium, unavoidable impurities, powerful titanium tantalum shape memory alloy,

(2) 25 mol% to 30 mol% tantalum and lmol% to 5 mol% α phase Stabilizing elements, the balance of titanium, unavoidable impurities, powerful titanium tantalum shape memory alloys,

 (3) 25 mol% or more and 30 mol% or less of tantalum, 0.1 mol% or more and lmol% or less of interstitial elements, the balance of titanium, unavoidable impurities, and powerful titanium tantalum shape memory alloy,

 (4) Titanium tantalum shape memory consisting of 20 mol% or more and 30 mol% or less tantalum, lmol% or more and 10 mol% or less of tantalum and / 3-phase stabilizing element, the balance of titanium, and inevitable impurities Alloy,

 (5) 25 mol% or more and 30 mol% or less of tantalum, 0.5 mol% or more and 2 mol% or less of transition metal element, the balance of titanium, unavoidable impurities, and powerful titanium Tantalum shape memory alloy,

 (6) 25 mol% or more and 30 mol% or less of tantalum, lmol% or more and 10 mol% or less of zirconium, the balance of titanium, unavoidable impurities, powerful titanium tantalum shape memory alloy,

 (7) 25 mol% or more and 30 mol% or less of tantalum, lmol% or more and 5 mol% or less of tin, the balance of titanium, unavoidable impurities, powerful titanium tantalum shape memory alloy,

(8) 20 mol% or more and 30 mol% or less of tantalum, additional elements added so that the total tantalum equivalent is 30 mol% or more and 39.5 mol% or less, the remaining titanium, unavoidable impurities, and powerful titanium tantalum System shape memory alloy,

 (9) The titanium tantalum-based shape memory alloy according to (8), wherein the additive element has an α-phase stabilizing element, an interstitial element, a / 3-phase stabilizing element, and a transition metal element. (10) The additive element includes zirconium having a concentration of 1 mol% or more and 5 mol% or less, and at least one element of an α-phase stabilizing element, an interstitial element, a / 3-phase stabilizing element, and a transition metal element ( 8) Titanium tantalum shape memory alloy,

 (11) The additive element has lmol% or more and 2mol% or less of tin and at least one element of α-phase stabilizing element, interstitial element, / 3-phase stabilizing element and transition metal element. (8) titanium tantalum-based shape memory alloy,

Formed by any one of the! / [0047] Thus, the piston ring of the present invention is characterized by the titanium tantalum-based shape memory alloy as the material. Therefore, first, the characteristics of the titanium tantalum-based shape memory alloy, which is the feature, will be described in detail with various experimental examples.

[0048] (Experimental example of titanium tantalum-based shape memory alloy as material)

 Examples of materials that can be used for the piston ring of the present invention (hereinafter referred to as “material examples of the present invention”), alloys 1 to 35 having the alloy compositions shown in Tables 1 to 7 below, and Tests of alloys 36 to 40 having the alloy compositions shown in Table 8 as examples of materials that cannot be used for the biston ring, that is, examples of materials other than the above components (hereinafter referred to as “comparative material examples”) A piece was made and tested.

 [0049] The test piece used in the experiment was prepared by the following methods (1) to (3).

 (1) The mol% of each metal element is measured and melted by the arc melting method to produce an alloy ingot. For example, alloy l (Ti—36Ta) is an alloy with a compound composition of 36 mol% Ta and the balance (64 mol%) Ti, and alloy 4 (Ti-30 Ta—1A1) is 30 mol% Ta and lmol An alloy with an alloy composition of% A1 and the balance (69 mol%) of Ti.

 (2) The produced alloy ingot is cold-rolled by a cold rolling mill at a rolling rate of 80% to 95% to produce a plate material.

 (3) A test piece having a length of 40 mm, a width of 1.5 mm, and a thickness of 0.1 mm is cut out from the plate material.

 [0050] Fig. 1 is an explanatory diagram of a shape memory characteristic evaluation test, Fig. 1A is an explanatory diagram of a typical strain temperature curve of an alloy exhibiting a repeated shape memory characteristic, and Fig. 1B shows a repeated shape memory characteristic. It is explanatory drawing of the typical strain temperature curve of the alloy which is not.

 [0051] <Transformation temperature measurement test>

 The transformation temperature of each alloy is the heat treatment of the cold-rolled material at 700 ° C for 1 hour, the differential scanning calorimetry (DSC), the martensitic transformation peak temperature (M * point), and the reverse transformation. Peak temperature (A * point) was measured.

[0052] The reverse transformation peak temperature obtained by differential scanning calorimetry is obtained when the temperature of the martensite phase (hereinafter sometimes referred to as "M phase") is increased from low temperature to the austenite phase (hereinafter referred to as "A"). Phase))) and the temperature rises and the M phase is reached. This is the intermediate temperature to the temperature at which reverse transformation to A phase is completed (Af temperature) (As temperature <reverse transformation peak temperature <Af temperature).

[0053] <Shape memory characteristic evaluation test>

 The shape memory characteristics of the alloys produced by the above production methods were tested and evaluated. In Table 1 and Table 8 below, the transformation temperature, which is a shape memory property, is obtained by performing a thermal cycle test (-100 ° C to 300 ° C) under a constant stress (lOOMPa) using a tensile tester. (As, M s) and shape recovery rate (%) were evaluated. That is, almost the same strain temperature curve as shown in FIG. 1A was measured for the alloys of the present invention material showing shape memory characteristics;! To 12 and alloy 40, and As (inverse) was measured from the measured strain temperature curve. Transformation start temperature) and Ms (martensitic transformation start temperature), transformation strain ε, recovery strain ε, and shape recovery rate (ε Α / ε

 M A M

 ) Was measured.

 [0054] In Alloy 36 to Alloy 40 (that is, a comparative material example) in which shape memory characteristics were not observed from the second cycle, almost the same strain temperature curves as shown in Fig. 1B were measured and measured. From the strain temperature curve, As (reverse transformation start temperature) in the first cycle was measured.

 [0055] Also, in Tables 2 to 7, using a tensile tester, 2% strain was applied at room temperature, and then two thermal cycles (room temperature to 250 ° C) were applied. The shape recovery rate of each cycle was evaluated.

 [0056] The tantalum equivalents (Ta equivalents) described in Tables 1 to 8 below are calculated by the following formula (1).

 [0057] Ta equivalent (mol%) = Ta (mol%) + 2.9 X Al (mol%) + 5.6 X Si (mol%) + 8.3 X (N (mol%) + B (mol% ) + C (mol%) +0 (mol%) + Mo (mol%)} + 3.9XV (mol%) + l.7XNb (mol%) + 6.4 X (Fe (mol%) + Mn (mol%)} + 5.0X {Co (mol%) + Cr (mol%)} + 4.2 X Ni (mol%) + 1.1 XZr (mol%) + 2.8XSn (mol%

)-(D

Note that the Ta equivalent equation (1) corresponds to the effect of changing the transformation temperature of the alloy when Ta or an element other than Ta is added. This is a formula for calculating (converting) force. This equation (1) is derived by the inventors' experiment, and by calculating the Ta equivalent, the force of how much the transformation temperature changes is derived ( The guessing power is S.

[0058] Compositions of alloys 1 to 3 which are examples of the present invention of binary alloys of Ti and Ta, and alloys 4 to 12 of the examples of the present invention in which other additive elements are added to Ti and Ta , 8 of the first cycle of each alloy 1 to alloy 12 (.0, 8 of the second cycle (.0, transformation strain E (%), recovery strain e (%), and shape recovery rate A / _f ) (% ) Measurement results and Ta equivalent (mol%) ¾

A M

 Not in Table 1.

[0059] [Table 1]

 Table 1. Transformation temperature and recovery rate of invention alloys

また、 Ti合金の低温安定相である α相から高温安定相である ø相へ相変態する温 度を上昇させる（α相を安定化させる）効果があり、 Tiの形状記憶特性が失われる原 因となる ω相の析出を抑え、熱安定性、形状回復性を高める《相安定化元素（本願 明細書では「Α群」と記載する。 )である A1 (アルミニウム）や Si (ケィ素）が添加された Ti Ta系三元合金である合金 4〜合金 6、合金 13の組成と、各合金 4〜合金 6、合 金 13の 1サイクル目の形状回復率（％)、 2サイクル目の形状回復率（％)および Ta当 量 (mol%)の計測結果を表 2に示す。

It also has the effect of increasing the temperature of phase transformation from the α phase, which is the low temperature stable phase of the Ti alloy, to the ø phase, which is the high temperature stable phase (stabilizing the α phase), and the shape memory characteristics of Ti are lost. A1 (aluminum) and Si (cyanide), which are the phase stabilizing elements (referred to as “本 願 group” in the present specification), which suppresses the precipitation of the ω phase, which increases the thermal stability and shape recoverability. The composition of alloy 4 to alloy 6 and alloy 13, which is a Ti Ta ternary alloy to which is added, and the shape recovery rate (%) of each alloy 4 to alloy 6 and alloy 13 in the first cycle, Table 2 shows the measurement results of the shape recovery rate (%) and Ta equivalent (mol%).

[Table 2] Table 2. Shape memory properties of invention alloys (Group A)

また、 ω相の析出を抑え、熱安定性、形状回復性を高めると共に、固溶硬化で塑性 変形を抑制する効果のある侵入型元素（本願明細書では「Β群」と記載する。 )である Ν (窒素）、 Β (ホウ素）、 Ο (酸素）、 C (炭素）が添加された Ti Ta系三元合金である 合 A7、合金 8、合金 14〜合金 16の組成と、各合金の 1サイクル目の形状回復率（％ ) ？サイクル目の形状回復率（％)および Ta当量 (mol% )の計測結果を表 3に示す

In addition, it is an interstitial element (denoted as “Β group” in the present specification) that has the effect of suppressing precipitation of ω phase, improving thermal stability and shape recovery, and suppressing plastic deformation by solid solution hardening. A composition of A7, Alloy 8, Alloy 14 to Alloy 16, and Ti Ta ternary alloy with added Ν (nitrogen), Β (boron), Ο (oxygen), and C (carbon) 1st cycle shape recovery rate (%)? Table 3 shows the measurement results of the shape recovery rate (%) and Ta equivalent (mol%) at the cycle.

[Table 3]

 Table 3. Shape memory properties of invention alloys (Group B)

Nb (niobium), a V-phase stabilizing element that stabilizes the 0 phase, which is the parent phase of the Ti alloy, and is an element of the same family as Ta (referred to as “C group” in this specification). The composition of alloy 9, alloy 11 and alloy 17 to alloy 20, which are Ti-Ta ternary alloys with (vanadium) added, and the shape recovery rate (%) of the first cycle of each alloy, the second cycle Table 4 shows the measurement results of the shape recovery rate (%) and Ta equivalent (mol%).

[Table 4] Table 4. Shape memory characteristics of invention alloys (Group C)

Mo (molybdenum), Cr (chromium), which is a zero-phase stabilizing element that stabilizes the zero phase of the Ti alloy and is a transition metal element (referred to as “group D” in the present specification), Ti—Ta ternary alloy with Fe (iron), M n (manganese), Co (cobalt), and Ni (nickel) added, composition of alloy 10, alloy 21 to alloy 26, and one cycle of each alloy Table 5 shows the measurement results of the eye shape recovery rate (%), the 2nd eye shape recovery rate (%), and the Ta equivalent (mol%).

 [Table 5] Table 5. Shape memory characteristics of invention alloys (Group D)

添加元素としての Zr (ジルコニウム）、 Sn (スズ）、が添加された Ti一 Ta系三元合金 である合金 12と合金 27〜合金 30の組成と、各合金の 1サイクル目の形状回復率（％ ) 、 2サイクル目の形状回復率（％)および Ta当量（mol%)の計測結果を表 6に示す

Compositions of Alloy 12 and Alloy 27 to Alloy 30, which are Ti-Ta-based ternary alloys to which Zr (zirconium) and Sn (tin) as additive elements are added, and the shape recovery rate of each alloy in the first cycle ( %), The measurement results of shape recovery rate (%) and Ta equivalent (mol%) in the second cycle are shown in Table 6.

Yes

 [00641 Note that Zr has the effect of increasing the transformation strain ε (see Table 1), and Sn is caused by solid solution hardening.

 M

 The effect of suppressing precipitation of ω phase can be expected.

[0065] [Table 6] Table 6. Shape memory characteristics of inventive alloys (Zr and Sri)

前記 α相安定化元素、侵入型元素、および 0相安定化元素が添加された Ti一 Ta 系多元（四元）合金である合金 31〜合金 35の組成と、各合金の 1サイクル目の形状 回復率（％)、 2サイクノレ目の形状回復率（％)および Ta当量 (mol%)の計測結果を 表 7に示す。

Compositions of alloys 31 to 35, which are Ti-Ta multi-element (quaternary) alloys to which the α-phase stabilizing element, interstitial element, and 0-phase stabilizing element are added, and the shape of each alloy in the first cycle Table 7 shows the measurement results of the recovery rate (%), the shape recovery rate (%) of the second cycle and the Ta equivalent (mol%).

 [Table 7]

 Table 7. Shape memory properties of invention alloys (multi-component)

 The composition of Alloy 36 to Alloy 40, which are comparative material examples, and the shape recovery rate (%) of the first cycle, the shape recovery rate (.) And Ta equivalent (mol%) of the second cycle of each alloy were measured. Table 8 shows.

 [0067] Alloy 36 is a Ti—22Nb binary alloy, and Alloy 37 is a Ti—27Ta binary alloy with a Ta content of 27 mol% (= 58 wt%) investigated as an example where Ta is 30 mol% or less. Alloy 38 and Alloy 39 are alloys with a Ta equivalent of 30 mol% or less, and Alloy 40 is a Ti—40Ta binary alloy.

[0068] In Table 8, in the case where the transformation start temperature Ms in the second cycle is not measured and the transformation strain ε _μ , the recovery strain ε, etc. are not measured, that is, the shape memory characteristic is in the first cycle.

 A

If lost, an “X” is added in Table 8. [0069] [Table 8]

¾8. Transformation temperature and recovery rate of comparative alloys

前記実験結果から、 Taが 30mol% 36mol%の Ti Ta系二元合金（合金 1〜合 金 3)では、 100°C以上の変態温度を示し、高い形状回復率が確認された。したがつ て、高温 (例えば 50°C (323K)以上）での熱サイクル下で、形状記憶合金として繰り し使用すること力 ^sできること力 S分力ゝつた。

From the above experimental results, the Ti Ta binary alloys (Alloy 1 to Alloy 3) with Ta of 30 mol% and 36 mol% showed a transformation temperature of 100 ° C. or higher and a high shape recovery rate was confirmed. Te the month, a thermal cycle under a high temperature (e.g. 50 ° C (323 K) or higher), it forces S component force can be force ^s use Shi repeatedly as the shape memory alloyゝivy.

[0070] Further, even if Ta is 30 mol% or less, the Ta equivalent of 30 mol% or more

 "High transformation temperatures and shape recovery rates were confirmed for Alloys 4 to 6 and Alloy 13 to which the phase stabilizing element (Al Si) was added (see Tables 1 and 2). << If the total amount of the phase stabilizing element (A 1) exceeds 5 mol%, the transformation temperature decreases, so it is desirable that the amount is 5 mol% or less.

 [0071] Further, from Tables 1 and 3, it is shown that an alloy to which an interstitial element of group B (NB 0 C) is added so that the Ta equivalent is 30 mol% or more even when Ta is 30 mol% or less. In Alloy 8, Alloy 14 and Alloy 16, high transformation temperature and shape recovery rate were confirmed. Note that the recovery rate tends to decrease as the number of interstitial elements increases from Alloy 7 and Alloy 8, and the cold workability at the time of specimen preparation decreases, and when the total amount exceeds lmol%, the cooling rate exceeds 80%. It was difficult to produce a test piece by hot rolling.

[0072] Further, from Tables 1 and 4, from alloy 9 and alloy to which an element of group C (Nb V) is added so that the Ta equivalent is 30 mol% or more even when Ta is 30 mol% or less. 11. In Alloy 17 to Alloy 20, a high transformation temperature and shape recovery rate were confirmed. From Alloy 9, Alloy 11 and Alloy 17 to Alloy 20, the recovery rate tends to decrease when the element of group C increases, and the transformation temperature also tends to decrease as the Ta equivalent increases. To ensure a recovery rate of 80% or higher In this case, it is preferable that the total amount does not exceed 10 mol%.

 [0073] Further, from Table 1 and Table 5, it is shown that even if Ta is 30 mol% or less, the Ta group element (Mo, Fe, Mn, Co, Cr, Ni) is such that the Ta equivalent is 30 mol% or more. In Alloy 10, Alloy 21 to Alloy 26 to which was added, a high transformation temperature and a shape recovery rate were confirmed. In addition, from Alloy 10 and Alloy 21, the recovery rate tends to decrease when the elements of Group D increase, cold workability deteriorates, and the transformation temperature also tends to decrease. When the total amount of the elements of Group D exceeds 2 mol%, it becomes difficult to produce a test piece by cold rolling of 80% or more. Therefore, it is desirable that the total amount of elements in Group D be 2 mol% or less! /.

 [0074] Further, from Tables 6 and 8, in the case of alloy 12 to which Zr and Sn are added, and alloy 27 to alloy 30 so that the Ta equivalent is 30 mol% or more even if Ta is 30 mol% or less. A high shape recovery rate was confirmed. From the results of Alloy 12, Alloy 27 to Alloy 30, Alloy 38, and Alloy 39, when Zr and Sn were increased, the recovery rate was decreased, the shape characteristics were lost, and the cold workability deteriorated. In addition, since the transformation temperature also decreases when the Ta equivalent becomes too large, it is desirable that the total amount of Zr does not exceed 10 mol%. It is desirable that Sn does not exceed 5 mol%. Furthermore, from Table 7, alloy 3 with elements of Group A, Group B, Group C, Group D, Zr, Sn added so that the Ta equivalent is 30 mol% or higher; Was confirmed.

 [0075] FIG. 2 is an explanatory diagram of the experimental results of the Ti Ta binary alloy of the present invention material example. FIG. 2A shows the relationship between the mole fraction of Ta and the transformation start temperature (Ms) under 5 OMPa. FIG. 2B is an explanatory diagram of strain temperature curves of Ti—32Ta and Ti—40Ta.

 FIG. 3 is an explanatory diagram of a strain temperature curve of the Ti 27Ta binary alloy of the material example of the present invention.

 [0077] In Table 1, Table 8, and Fig. 2, from the experimental results of Alloy 1 to Alloy 3 and Alloy 40 and Fig. 2, Ti

 In the Ta binary alloy, if the Ta content is 40 mol% or more, the transformation temperature will be 50 ° C or less, and shape recovery will not be possible under a high temperature (50 ° C or more) thermal cycle. Figure 2B also shows that the shape recovery rate tends to decrease.

[0078] Further, from the experimental results of Alloy 1 to Alloy 3 and Alloy 37 and Fig. 3, in the case of Ti Ta binary alloy, when Ta is less than 30 mol%, the transformation temperature increases, but the shape recovery effect is 1 Only in the second cycle, the shape recovery effect is not observed in the second and subsequent cycles (see “X” in Table 8), and the ω phase is analyzed and the shape memory characteristics are lost. Ta is less than 30mol% There was also a problem that plastic deformation could not be used repeatedly.

FIG. 4 is an explanatory diagram of a strain temperature curve of a Ti 22Nb binary alloy as a comparative material example.

[0080] From the experimental results of Alloy 36 in Table 8 and Fig. 4, Ti 22Nb has the same transformation temperature as Ti 32Ta, but the shape memory characteristics are lost after the second cycle as shown in Fig. 4. It has been confirmed that it is thermally unstable simply by thermal expansion and contraction.

Therefore, by using the titanium tantalum-based shape memory alloy as described above as an example of the material of the present invention as a material for the piston ring, it is appropriate that the tension is low in the low temperature and low load state, and the friction loss. The piston ring with increased tension can be realized by transformation under high temperature and high load conditions of 80 ° C or higher.

 FIG. 5 is a schematic cross-sectional view of an example of the piston ring of the present invention.

 The piston ring 30 of the present invention shown in FIG. 5 is a piston ring composed of only one ring 30, and the one ring 30 is formed of the titanium tantalum-based shape memory alloy described above.

 [0084] The piston ring 30 of the present invention is characterized by its material, and its shape and the like are not particularly limited.

[0085] For example, in a piston ring including only one ring 30 shown in FIG. 5, the bore diameter is appropriately designed according to the size of the internal combustion engine in which the piston ring 30 is used, the shape of the piston, and the like. In this case, it is preferable to have a thickness of about φ65 to about 100 mm, but the thickness is preferably about 0.7 to 4 mm.

[0086] Here, when the bore diameter is about 65 to 90 mm, the thickness is preferably about 0.7 to 3 mm, and the tension in the diameter expansion direction of the piston ring 30 at that time is particularly preferable. Is 0.;! To 25N at room temperature, and preferably 0.2 to 55N after reverse transformation (austenite transformation).

[0087] On the other hand, when the bore diameter is about 90 to 100 mm, the thickness is particularly preferably about 0.7 to 4 mm. The tension in the diameter expansion direction of the piston ring 30 at that time is As described above, it is preferably 0.;! To 25N at room temperature, and preferably 0.2 to 55N after reverse transformation (austenite transformation)! /. Note that the piston ring 30 according to the present invention is not limited to the substantially rectangular shape shown in the drawing, and the cross-sectional shape that may be subjected to conventionally known surface processing or the like is not limited to the illustrated rectangular shape. It is possible to take a shape.

 FIG. 6 is a schematic sectional view showing another example of the piston ring of the present invention. FIG. 6 (a) shows a piston ring 40 composed of a piston ring body 41 and a coil expander 42. FIG. 6B is a schematic cross-sectional view of a piston ring 50 including a piston ring main body 51 and a plate expander 52. FIG. 6 (c) to (e) are schematic cross-sectional views of the side rings 44, 61, 71 and the spacer rings 45, 62, 72 and the piston rings 43, 60, 70 composed of forces. It is.

 [0090] Fig. 6 As shown, the piston ring of the present invention 40, 43, 50, 60, 70 and so on (together with the piston ring body 41, 51, or the side lanes 44, 61, 71 and the expander) 42, 45, 52, 62, 72 and / or at least one of them is made of the shape memory alloy described above, and the piston rings 40, 43, 50, 60, 70ί of the present invention ( In addition, it is preferable that the special copper spanders 42, 45, 52, 62 and 72 are made of a shape memory alloy, compared to the piston ring bodies 41 and 51 and the side lanes 44, 61 and 71. 45, 52, 62, and 72 contribute to the tension of the entire piston ring.

 [0091] In this case as well, as with the piston ring 30 shown in Fig. 5, the size, shape, etc. are not particularly limited. Is preferred.

 [0092] The piston ring of the present invention can be used for an oil ring or a pressure ring.

 Example

 [0093] The piston ring of the present invention will be described more specifically with reference to examples.

 [0094] (Example 1)

Using the alloy material 7 of the present invention described above, the coil outer diameter was 1.4 mm, and a coil expander was manufactured so that the tension at the high temperature was the same as in the comparative example described later. (made of, C mass _{^{0/0: 0. 5, Si}} : 0. 2, Mn: 0. 3, P: 0. 02, S: 0. 015, Cr: 10. 2, balance Fe, and unavoidable Fig. 6 (a) Thus, the piston ring of Example 1 of the present invention was produced.

[Example 2]

 In the same manner as the piston ring of Example 1, the piston ring of Example 2 was produced using the alloy 11 of the material of the present invention described above.

[0096] (Example 3)

 In the same manner as the piston ring of Example 1, the piston ring of Example 3 was produced using the alloy 4 of the material of the present invention described above.

[Example 4]

 In the same manner as the piston ring of Example 1, the piston ring of Example 4 was produced using the alloy 5 of the material of the present invention described above.

[0098] (Comparative Example 1)

 As a comparative example of the piston ring of the present invention, a Ti-Ni (Ti-50at% Ni material) shape memory alloy, which is a conventionally known shape memory alloy, has a reverse transformation peak temperature of 58 ° C. A coil expander having a temperature of 65 ° C. after completion of the state (end of austenite transformation) and combining this with the same piston ring main body as in Example 1 is shown in FIG. 6A. The piston ring of Comparative Example 1 was prepared.

[0099] <Fuel efficiency test>

 Using the piston rings of Examples 1 to 4 and the piston ring of Comparative Example 1, a fuel efficiency effect test was performed.

 [0100] Specifically, each piston ring was used as an oil ring, and the other first pressure ring and the second pressure ring were all conventionally known rings having the same specifications. Each was mounted on a φ88mm piston in an internal combustion engine, and the fuel consumption was measured in 10 · 15 mode. On the other hand, with the exception of using a conventional coil expander made of spring steel, all other conditions were prepared with the same piston rings (top ring, second ring) as in the examples and comparative examples, and the fuel consumption was measured in the same way. did.

[0101] For each measurement result, the fuel efficiency improvement rate when the piston ring of Comparative Example 1 was installed compared to the fuel efficiency when the coil expander made of the conventional spring steel was used as a reference (1), When the piston rings of Examples 1 to 4 of the present invention are mounted, The fuel efficiency effect ratio (improvement rate) was quantified.

[0102] The results are shown in Table 9.

[0103] [Table 9]

上記表 9からも明らかなように、本発明のピストンリングは、比較例 1のピストンリング 、つまり従来公知の形状記憶合金 (Ni— Ti系）が用いられて!/、るピストンリングに比べ て約 4〜5倍の燃費効率が得られることが分かった。

As is apparent from Table 9 above, the piston ring of the present invention uses the piston ring of Comparative Example 1, that is, a conventionally known shape memory alloy (Ni-Ti system)! It was found that the fuel efficiency was about 4-5 times.

Claims

The scope of the claims  [1] More than 30mol% and less than 40mol%! /, Tantanore,  The remaining titanium,  Inevitable impurities,  A piston ring made of a titanium tantalum-based shape memory alloy.  [2] 25 mol% or more and 30 mol% or less of tantalum,  lmol% or more and 5mol% or less α-phase stabilizing element,  The remaining titanium,  Inevitable impurities,  A piston ring made of a titanium tantalum-based shape memory alloy.  [3] 25 to 30 mol% tantalum,  0. lmol% to lmol% interstitial elements,  The remaining titanium,  Inevitable impurities,  A piston ring made of a titanium tantalum-based shape memory alloy.  [4] 20 mol% or more and 30 mol% or less of tantalum,  β-phase stabilizing element of the same family as tantalum in the range of lmol% to 10mol%  The remaining titanium,  Inevitable impurities,  A piston ring made of a titanium tantalum-based shape memory alloy.  [5] 25 to 30 mol% tantalum,  0.5 to 5 mol% to 2 mol% of transition metal element,  The remaining titanium, With inevitable impurities, A piston ring made of a titanium tantalum-based shape memory alloy.  [6] 25 mol% or more and 30 mol% or less of tantalum,  lmol% or more and 10mol% or less of zirconium,  The remaining titanium,  Inevitable impurities,  A piston ring made of a titanium tantalum-based shape memory alloy.  [7] 25 mol% or more and 30 mol% or less of tantalum,  1 mol% or more and 5 mol% or less of tin,  The remaining titanium,  Inevitable impurities,  A piston ring made of a titanium tantalum-based shape memory alloy.  [8] 20 mol% or more and 30 mol% or less of tantalum,  An additive element added so that the total tantalum equivalent is 30 mol% or more and 39.5 mol% or less, and  The remaining titanium,  Inevitable impurities,  A piston ring made of a titanium tantalum-based shape memory alloy. [9] The additive element is  a phase stabilizing element, interstitial element, β phase stabilizing element and at least one element of transition metal element,  The piston ring according to claim 8, comprising: [10] The additive element is  1 mol% or more and 5 mol% or less of zirconium, a phase stabilizing element, interstitial element, β phase stabilizing element and transition metal element One element and  The piston ring according to claim 8, comprising: [11] The additive element is  1 mol% or more and 2 mol% or less of tin,  at least one element of a phase stabilizing element, interstitial element, β phase stabilizing element and transition metal element,  The piston ring according to claim 8, comprising: [12] The piston ring is composed of a piston ring main body and an expander that is self-aligned with an inner circumferential surface 佃 j of the piston ring main body.  2. The piston ring according to claim 1, wherein both or one of the piston ring main body and the expander is formed of the titanium tantalum shape memory alloy. 13. The piston ring according to claim 12, wherein the expander is either a coil expander or a plate expander. [14] The piston ring includes a side rail and a spacer expander, and both or one of the side rail and the spacer expander is formed of the titanium tantalum shape memory alloy. The piston ring according to any one of claims 1 to 11, wherein the piston ring is provided. [15] The shape memory alloy has a tension at a temperature lower than the reverse transformation peak temperature of 0.;! To 25N, and the tension at a temperature equal to or higher than the reverse transformation peak temperature of the shape memory alloy is 0.2 to 55N. The piston ring according to any one of claims 1 to 14, wherein the piston ring is provided. [16] The piston ring according to any one of claims 1 to 15, wherein the piston ring is used as an oil ring or a pressure ring.