JP2020198181A - Thermal shock-resistant container - Google Patents

Abstract

To provide a thermal shock-resistant container that is not easily damaged when an arc is extinguished.SOLUTION: A thermal shock-resistant container of the present disclosure is made of ceramic and has a cap shape including an upper part and a side part that is connected to the upper part and extends cylindrically. When a direction in which the side part extends is a first direction, in a region R that is located near the upper part of the length of the side part divided into three equal parts in the first direction, an average value A of aspect ratios of a plurality of pores in a cross section of the region R along the first direction is 1.4 or more.SELECTED DRAWING: Figure 2

Description

The present disclosure relates to a heat-resistant impact container.

Demand for environmentally friendly vehicles such as EVs (Electric Vehicles) is increasing against the backdrop of growing awareness of environmental issues such as global warming. Such eco-friendly vehicles are equipped with EV relays so that the secondary battery and the motor / inverter can be safely turned on and off.

Here, the EV relay is provided with an upper portion and a side portion connected to the upper portion and extends in a tubular shape, and a cap-shaped heat-resistant impact container (container for EV relay) in which a portion surrounded by the side portion is open. It has. The heat-resistant impact container has a through hole at the top. The EV relay is further movable with a fixed terminal located in the through hole, a movable terminal located opposite to the fixed terminal in the heat-resistant impact container, and a metal member located at the opening of the heat-resistant shock container. It is equipped with an elastic body such as a spring that connects terminals and metal members. When the EV relay is on, the movable terminal is in contact with the fixed terminal, and when the EV relay changes from on to off, the movable terminal is separated from the fixed terminal.

Ceramics are widely used in such heat-resistant impact containers from the viewpoint of insulation and heat resistance (see, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2012-89489

When the EV relay changes from on to off, when the movable terminal separates from the fixed terminal, an arc (arc-shaped discharge spark) is generated between the fixed terminal and the movable terminal. This arc is extinguished by extending the arc with a magnetic field (hereinafter referred to as extinguishing the arc).

In recent years, secondary batteries used in eco-friendly vehicles have been replaced by nickel-metal hydride batteries and lithium-ion batteries. Here, when a lithium ion battery is used, the current flowing when the EV relay is on becomes a high voltage and a large current, so that the discharge voltage of the arc generated when the EV relay changes from on to off is large.

In this way, when the discharge voltage of the arc becomes large, when the arc is extinguished, a large amount of heat energy is applied to the heat-resistant impact container, and a crack is formed in the side portion of the heat-resistant impact container near the upper part to break the arc. It's easy to do. At this time, the crack growth direction is the thickness direction of the side portion.

The present disclosure has been devised in view of such circumstances, and an object of the present disclosure is to provide a heat-resistant impact container that is not easily damaged when the arc is extinguished.

The heat-resistant impact container of the present disclosure is made of ceramics and has a cap shape including an upper portion and a side portion connected to the upper portion and extending in a tubular shape. Then, when the direction in which the side portion extends is set as the first direction, in the region R located near the upper portion of the length of the side portion in the first direction divided into three equal parts, the said region R. The average value A of the aspect ratios of the plurality of pores in the cross section along the first direction is 1.4 or more.

The heat-resistant impact container of the present disclosure is not easily damaged during use.

It is a perspective view which shows an example of the EV relay provided with the heat-resistant shock container of this disclosure. It is a vertical cross-sectional view which shows an example of the EV relay provided with the heat-resistant shock container of this disclosure. It is a schematic diagram which shows an example of the cross section along the 1st direction in a region R. It is a schematic diagram which shows an example of the cross section along the 2nd direction in a region R.

The heat-resistant impact container of the present disclosure will be described in detail below with reference to the drawings.

FIG. 1 is a perspective view showing an example of an EV relay including the heat-resistant impact container of the present disclosure, and FIG. 2 is a vertical sectional view.

As shown in FIGS. 1 and 2, the EV relay 20 includes a heat-resistant impact container 10 having a through hole 3, a fixed terminal 4, a movable terminal 5, an elastic body 6, and a metal member 7. The heat-resistant impact container 10 has a cap shape including an upper portion 1 and a side portion 2 connected to the upper portion 1 and extending in a tubular shape. The extending direction of the side portion 2 is the direction indicated by the reference numeral F in FIG. 2, and this direction is the first direction. Further, the direction orthogonal to the first direction is the second direction, which is indicated by reference numeral S in FIG.

Further, in the heat-resistant impact container 10 alone, the portion surrounded by the inner surface 2a of the end portion (the portion away from the upper portion 1) of the side portion 2 is open, and the portion from this opening to the upper portion 1 is a space. It is in the shape of a cap. In addition, in FIG. 1 and FIG. 2, the front view shape of the upper portion 1 is shown as a quadrangular shape, but the shape is not limited to this shape and may be a circular shape.

The heat-resistant impact container 10 of the present disclosure is made of ceramics and has a plurality of pores. As the ceramics, aluminum oxide ceramics, silicon nitride ceramics, aluminum nitride ceramics, silicon carbide ceramics and the like can be used. Among the ceramics, when the heat-resistant impact container 10 is made of aluminum oxide ceramics, the ceramics have excellent mechanical properties while being relatively inexpensive including the raw material price and the manufacturing cost.

Here, the aluminum oxide ceramics are those containing 70% by mass or more of aluminum oxide out of 100% by mass of all the components constituting the ceramics. The same applies to other ceramics.

The material of the heat-resistant impact container can be confirmed by the following method. First, the target heat-resistant impact container is measured using an X-ray diffractometer (XRD), and the obtained value of 2θ (2θ is a diffraction angle) is collated with the JCPDS card. Here, a case where the presence of aluminum oxide is confirmed by XRD will be described as an example. Next, a quantitative analysis of aluminum (Al) is performed using an ICP emission spectroscopic analyzer (ICP) or a fluorescent X-ray analyzer (XRF). If the content, which is the value converted from the Al content measured by ICP or XRF to aluminum oxide (Al ₂ O ₃ ), is 70% by mass or more, the material of the heat-resistant impact container is aluminum oxide ceramics. is there.

Then, in the heat-resistant impact container 10, the boundary between the upper portion 1 and the side portion 2 is an extension line of the inner surface 2 of the upper portion 1. Then, the length from this extension line to the end of the side portion 2 is defined as the length of the side portion 2. Since the side portion 2 extends in the first direction, it can also be said to be the length of the side portion 2 in the first direction. Further, the distance from the inner surface 2a to the outer surface 2b is the thickness of the side portion 2. Then, as shown in FIG. 2, the portion located near the upper portion 1 of the length of the side portion 2 in the first direction divided into three equal parts is defined as the region R.

The size of the thermal shock container 10, for example, a is 300 mm ² ～1500Mm ² about the size of the top of the front view, a length 15mm~35mm side 2, the thickness of the sides 1mm~ It is 8 mm.

Next, FIG. 3 is a schematic view showing an example of a cross section along the first direction in the region R. In FIG. 3, the direction from top to bottom is the first direction, and the left-right direction is the second direction. As for the positional relationship, the upper portion 1 is located above the schematic drawing shown in FIG. 3, and the inner surface 2a or the outer surface 2b of the side portion 2 is located in the depth direction in FIG.

The heat-resistant impact container 10 of the present disclosure has an average value A of aspect ratios of a plurality of pores of 1.4 or more in a cross section along the first direction of the region R. Here, the aspect ratio is the major axis divided by the minor axis in one pore. The major axis is the length of the longest portion of the pores of interest, and the minor axis is the length of the longest portion in the direction perpendicular to the major axis. In FIG. 3, the major axis is aligned in the second direction and the minor axis is aligned in the first direction so as not to complicate the figure.

In the heat-resistant impact container 10 of the present disclosure, the mean value A of the aspect ratios of a plurality of pores is 1.4 or more in the cross section along the first direction of the region R, so that the existing pores have a major axis as a diameter. Since the area occupancy is smaller and heat is more likely to be transferred in the first direction than when the circular shape is formed, such pores are less likely to be the starting points of cracks when the arc is extinguished. On the other hand, when the average value A of the aspect ratios of the plurality of pores is less than 1.4, the heat transfer effect in the first direction is small.

The average value A of the aspect ratios of the plurality of pores may be 2.0 or less. When such a configuration is satisfied, the pores are unlikely to be the starting points of cracks while having a heat transfer effect in the first direction.

Further, the porosity in the region R may be 10% or less. When such a configuration is satisfied, since there are not too many pores, it is unlikely to be a starting point of cracks while having a heat transfer effect in the first direction. Although the lower limit is not set for the porosity in the above, the heat-resistant impact container of the present disclosure has a plurality of pores, and the porosity is not 0%. If it is described as the lower limit value, it is 1%.

Further, the average value of the distances between the centers of gravity of the plurality of pores in the region R may be 40 μm or more. When such a configuration is satisfied, the pores are not too close to each other, so that the pores are less likely to be the starting point of cracks while having a heat transfer effect in the first direction. Regarding the average value of the distances between the centers of gravity of a plurality of pores, the upper limit value is not set in the above, but it does not mean that they are infinitely separated. If it is described as an upper limit value, it is 200 μm or less.

Next, FIG. 4 is a schematic view showing an example of a cross section in the second direction orthogonal to the first direction of the region R. In No. 4, the inner surface 2a is located above the outside of the schematic diagram, and the outer surface 2b is located below. The inner surface 2a may be located below and the outer edge 2b may be located above. The depth direction on the illustrated surface is the first direction.

In the heat-resistant impact container 10 of the present disclosure, the average value B of the aspect ratios of the plurality of pores in the cross section along the second direction orthogonal to the first direction of the region R may be smaller than the average value A. If the mean value A is 1.4, then the mean value B is less than 1.4. Further, since the aspect ratio of the perfect circle is 1, the average value B is 1 or more and less than 1.4. Furthermore, the shapes of the plurality of pores in the cross section in the second direction orthogonal to the first direction of the region R may be closer to a perfect circle than the shapes of the plurality of pores confirmed in the first direction of the region R. You can also do it.

When such a configuration is satisfied, heat is not easily transferred in the thickness direction (second direction) of the side portion 2 which is the vertical direction in the drawing, so that heat is easily transferred in the first direction.

Further, the heat-resistant impact container 10 of the present disclosure has an average length 1 of a plurality of pores in the first direction in a cross section along the first direction of the region R and a second direction orthogonal to the first direction of the region R. The average length 2 / average length 1 may be 1.4 or more with respect to the average length 2 of the plurality of pores in the second direction in the cross section along the line. When satisfying such a configuration, the pores are less likely to be the starting point of cracks when the arc is extinguished.

Next, the average value A of the aspect ratios of the plurality of pores in the cross section along the first direction of the region R (hereinafter, may be simply referred to as the average value A), the porosity in the region R (hereinafter, simply the pores). It may be described as a rate), an average value of the distances between the centers of gravity of a plurality of pores in the region R (hereinafter, may be simply described as an average value of the distances between the centers of gravity), and orthogonal to the first direction of the region R. A method of measuring the average value B (hereinafter, may be simply referred to as the average value B) of the aspect ratios of a plurality of pores in the cross section along the second direction will be described.

First, the region R is cut along the first direction, and the cross section obtained by polishing this cut surface with a cross section polisher (CP) is defined as the first surface. Further, a cross section obtained by cutting along a second direction orthogonal to the first direction and polishing this cut surface with a cross section polisher (CP) is used as the second surface. For the average value A, the porosity, and the average value of the distance between the centers of gravity, observe the first surface. For the average value B, the second surface is used as the observation surface.

Next, each observation surface is photographed at a magnification of 500 times using a microscope (for example, a digital microscope VHX-5000 of KEYENCE CORPORATION). Then, for the range of the photographed photograph, for example, the area of 200,000 μm ² or more and 8,000,000 μm ² or less, the image analysis software “A image-kun” (registered trademark, manufactured by Asahi Kasei Engineering Co., Ltd. When "A image-kun" is written, it means image analysis software manufactured by Asahi Kasei Engineering Co., Ltd.). For the mean value A and the mean value B, the pores are regarded as particles in the measurement, and a technique called "particle analysis" is applied to measure the maximum length and the minimum width of each pore. The average value A and the average value B are obtained from the average value of the values obtained by dividing the maximum length of each pore by the minimum width. Similarly, the porosity is obtained by applying a method called particle analysis and calculating the ratio of the total area of the pores to the total measured area (area ratio (%)). For the distance between the centers of gravity, a method called dispersion measurement is applied. Here, as the analysis conditions of the image analysis software "A image-kun", for example, the brightness of the particles is "dark", the binarization method is "automatic", the small figure removal area is 0.1 μm, and the noise removal filter is used. "Yes", the binarized image correction may be "straight line separation", and the display method may be "superimposition".

Next, the method for manufacturing the heat-resistant impact container of the present disclosure will be described below. Here, a case where the heat-resistant impact container is made of aluminum oxide ceramics will be described as an example.

First, aluminum oxide (Al ₂ O ₃ ) powder is prepared as a main raw material. Further, as a sintering aid, silicon oxide (SiO ₂ ) powder, calcium carbonate (CaCO ₃ ) powder and magnesium carbonate (MgCO ₃ ) powder are prepared.

Next, each powder (main raw material and firing aid) is weighed and mixed so that the content of aluminum oxide becomes 70% by mass or more after firing, and ion-exchanged water and a dispersant are further added to be known. The primary slurry is prepared by the above method, for example, wet pulverization with a ball mill.

Here, when the total of the above powders (the total of the above powders is referred to as solid content) is 100 parts by mass, the ion-exchanged water is added so that the water content in the primary slurry is 30 to 80 parts by mass. Added. As a dispersant, ammonium polyacrylate (PAA) or the like is added in an amount of 0.02 part by mass or more and 0.5 part by mass with respect to 100 parts by mass of solid content.

Next, an organic binder and a mold release agent are added to the primary slurry and further mixed to prepare a secondary slurry. Here, the organic binder is added in an amount of 6 parts by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the solid content. Further, as the binder, an acrylic resin having a molecular weight of about 1000 to 100,000 is used.

Next, the secondary slurry is spray-dried by a known method to prepare granules. Here, the rotation speed of the disc during spray drying of the slurry is 5000 rpm or more and 10000 rpm or less.

Next, a mold having a shape to be a heat-resistant impact container is prepared. Then, the mold is filled with granules and uniaxial press molding is performed. At this time, the press forming pressure is 50 MPa or more and 170 MPa or less. Then, by firing by a known firing method, a heat-resistant impact container can be obtained.

In order to make the average value A 2.0 or less, the water content in the primary slurry may be 40 to 60 parts by mass, and the press forming pressure may be 60 MPa or more and 170 MPa or less.

Further, in order to reduce the porosity in the region R to 10% or less, the amount of the dispersant added to the primary slurry should be 0.02 parts by mass or more and 0.2 parts by mass or less with respect to 100 parts by mass of the solid content. Good.

Further, in order to make the average value of the distances between the centers of gravity of the plurality of pores in the region R 40 μm or more, the rotation speed of the disk at the time of spray drying of the slurry may be 6000 rpm or more and 10000 rpm or less. At this time, since the diameter of the disc is about 8 cm to 21 cm, the peripheral speed of the disc is 25 m / sec or more and 110 m / sec or less.

Further, in order for the average value B of the aspect ratios of the plurality of pores in the cross section in the second direction orthogonal to the first direction of the region R to be smaller than the average value A, the water content in the primary slurry is 30 to 30 to. 60 parts by mass, press molding pressure is 100 MPa or more and 170 MPa or less.

1: Upper part 2: Side part 2a: Inner surface 2b; Outer surface 3 (3a, 3b): Through hole 4 (4a, 4b): Fixed terminal 5: Movable terminal 6: Elastic body 7: Metal member 10: Heat-resistant impact container 20 : EV relay

Claims (5)

Made of ceramics
At the top and
It is a cap shape having a side portion connected to the upper portion and extending in a tubular shape.
When the direction in which the side portion extends is the first direction, in the region R located near the upper portion of the length of the side portion in the first direction divided into three equal parts.
A heat-resistant impact container having an average value A of aspect ratios of a plurality of pores in a cross section of the region R along the first direction of 1.4 or more. The heat-resistant impact container according to claim 1, wherein the average value A of the aspect ratio is 2.0 or less. The heat-resistant impact container according to claim 1 or 2, wherein the porosity in the region R is 10% or less. The heat-resistant impact container according to any one of claims 1 to 3, wherein the average value of the distances between the centers of gravity of the plurality of pores in the region R is 40 μm or more. The invention according to any one of claims 1 to 4, wherein the average value B of the aspect ratios of the plurality of pores in the cross section of the region R in the second direction orthogonal to the first direction is smaller than the average value A. Heat-resistant impact container.

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