JP2020101710A - Insulating member of thermostat, fixing device, and image forming apparatus - Google Patents

Abstract

To make it possible to ensure insulating properties of a thermostat, even when an insulating distance required as standards for safety cannot be ensured in using a thermostat including an attachment flange part, without adding a change to the configuration of the thermostat itself.SOLUTION: An insulating member 60 is attached to a thermostat 40. The insulating member 60 includes an engaging attachment part 61 that is removably engaged with a surface part closer to a base end than a flange part 42 on an outer peripheral surface of a thermostat case 41, and an insulating body part 62 that projects from an outside wall of the engaging attachment part 61 and is located between terminal connection parts 43 and the attachment flange part 42.SELECTED DRAWING: Figure 9

Description

The present invention relates to a thermostat insulating member, a fixing device, and an image forming apparatus.

Generally, in an electrophotographic image forming apparatus, the surface of an image bearing member such as a photoconductor is irradiated with laser light to form an electrostatic latent image, and the electrostatic latent image is visualized as a toner image by a developing device. .. Then, after transferring the toner image to a recording medium such as paper, the fixing device fixes the toner image on the recording medium.

The fixing device includes a heating rotator that is heated by a heater and the like, and a pressure rotator that presses a recording medium against the heating rotator. Then, the recording medium on which the toner image is formed is passed between the heating rotator and the pressure rotator, and the toner image is melted by heating and pressing to be fixed on the recording medium.

This type of fixing device may include a thermostat in order to prevent overheating (abnormal temperature rise) of the heating rotator (see, for example, Patent Document 1). This thermostat is provided in the energization path that connects the power supply unit and the heater. The thermostat is configured to cut off the power supply path from the power supply unit to the heater when the temperature of the heating roller exceeds a predetermined temperature.
This thermostat has a thermostat case for accommodating biometal and a breaking circuit. The thermostat case has a substantially cylindrical shape and is attached to the bracket member. The bracket member is formed with a cylindrical engagement hole that engages with the thermostat case. The thermostat case is inserted into the engagement hole so that the front end surface faces the heating rotator. The base end portion of the thermostat case is provided with a pair of terminal connection portions that project outward in the radial direction. A wiring terminal such as a crimp terminal is connected to each terminal connecting portion.

JP, 2007-33706, A

FIG. 17 shows a variation of the mounting shape of the thermostat. In this example, a mounting flange 102 made of sheet metal is formed on the outer peripheral surface of the thermostat case 101 so as to project. The thermostat case 101 is fixed to the bracket member via the mounting flange portion 102. A pair of terminal connection plates 103 is provided at the base end of the thermostat case 101. Reference numeral 104 in the drawing indicates a wiring terminal connected to each terminal connection plate 103.

Here, when installing the thermostat, it is necessary to secure a specified insulation distance from the viewpoint of ensuring the safety of the product. An example of the insulation distance is a spatial distance. In the case of the thermostat having the above-described sheet metal mounting flange portion 102, the spatial distance corresponds to the distance between the wiring terminal 104 connected to the terminal connecting plate 103 and the mounting flange portion 102. As for this clearance, the minimum required distance (hereinafter referred to as required insulation distance) is defined by international safety standards such as IEC standards.
This required insulation distance may be changed by reviewing safety standards. Conventionally, when the required insulation distance has been changed, the position of the mounting flange portion 102 of the thermostat and the shape of the thermostat case 101 have been changed by design changes.

However, in this case, it is necessary to discard the existing thermostat and replace it with a thermostat that meets safety standards, which causes a problem of increasing costs.

The present invention has been made in view of such a point, and its object is to provide an inexpensive configuration without changing the configuration of the thermostat itself when the required insulation distance defined by the safety standard cannot be secured. It is to ensure the insulation of the thermostat.

The insulating member according to one aspect of the present invention is attached to a thermostat.

The thermostat includes a substantially cylindrical thermostat case, a mounting flange portion that projects radially outward from an outer peripheral surface of the thermostat case, and a wiring terminal provided at a base end portion of the thermostat case. And a pair of terminal connecting parts to which the thermostat case is inserted into a through hole formed in the bracket member, and is fixed to the bracket member through the mounting flange part. There, the insulating member, the engaging mounting portion that is detachably engaged with the surface portion of the outer peripheral surface of the thermostat case on the base end side of the mounting flange portion, and protruding from the outer wall surface of the engaging mounting portion, Each of the wiring terminals connected to the pair of terminal connection portions and the insulating main body portion configured to cut off between the mounting flange portion are provided.

A fixing device according to another aspect of the present invention includes the thermostat to which the insulating member is mounted, the bracket member, a heating rotator heated by a heater, and the heating rotator pressed against the heating rotator. And a pressure rotator forming a nip portion through which a recording medium passes, and the thermostat is configured to cut off energization to the heater when the temperature of the heating rotator reaches a predetermined temperature. ing.

An image forming apparatus according to another aspect of the present invention includes the fixing device.

According to the present invention, when the required insulation distance defined by the safety standard cannot be secured, it is possible to secure the insulating property of the thermostat with an inexpensive configuration without changing the configuration of the thermostat itself.

FIG. 1 is a schematic diagram of an image forming apparatus including a fixing device in which the insulating member according to the embodiment is used. FIG. 2 is an external perspective view showing the fixing device. FIG. 3 is a cut perspective view of the fixing device taken along a vertical plane along the axis of the thermostat. FIG. 4 is a side view of the frame member of the left divided portion of the fixing device as viewed from the outside (left side) of the device. FIG. 5 is a side view showing the thermostat. FIG. 6 is a view on arrow VI in FIG. FIG. 7 is a schematic diagram showing the internal structure of the thermostat. FIG. 8 is an enlarged view showing a thermostat mounting portion of the frame member in an enlarged manner. FIG. 9 is a perspective view showing a state in which an insulating member is attached to the thermostat of FIG. FIG. 10 is a table showing the required insulation distance for each voltage defined by the international safety standard (IEC60950-1). FIG. 11 is a table showing correction factors for required insulation distance according to altitude. FIG. 12 is a perspective view showing an insulating member mounted on the thermostat. FIG. 13 is a plan view of the insulating member as seen from the axial direction. FIG. 14 is a perspective view of the insulating member as seen from the seat surface side opposite to the open portion side. FIG. 15: is explanatory drawing for demonstrating the procedure of attaching an insulating member to a thermostat. FIG. 16 is a view corresponding to FIG. 15 showing a state in which the mounting of the insulating member on the thermostat is completed. FIG. 17 is a schematic view showing a variation of the mounting shape of the thermostat in the conventional example.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The present invention is not limited to the following embodiments.

<<Embodiment>>
FIG. 1 shows an image forming apparatus 1 including a fixing device 30 in which an insulating member 60 according to this embodiment is used. The image forming apparatus 1 is composed of a laser printer in this embodiment. In the following description, the front side and the rear side mean the front side and the rear side of the image forming apparatus 1 (the front side and the back side in the direction perpendicular to the paper surface of FIG. 1), and the left side and the right side respectively indicate the image forming apparatus. 1 means the left side and the right side when viewed from the front side.

[Overall Configuration of Image Forming Apparatus 1]
The image forming apparatus 1 includes a housing 3 that houses the image forming unit 2. A paper feed unit 4 is provided in the lower portion of the housing 3, and a paper discharge unit 5 is formed on the upper surface of the housing 3.

A plurality of transport roller pairs 7 to 9 that sandwich and transport the paper P (an example of a recording medium) are arranged in a paper transport path 6 that extends from the paper feed unit 4 to the paper discharge unit 5.

The paper feeding unit 4 has a paper feeding cassette 4a and a pickup roller 4b. Sheet-shaped paper P is stored in the paper feed cassette 4a. The pickup roller 4b takes out the paper P in the paper feed cassette 4a and sends it out of the cassette. The paper P sent from the paper feed cassette 4 a to the outside of the cassette is supplied to the image forming unit 2 via the pair of transport rollers 7.

The image forming unit 2 includes a photosensitive drum 15, a charging device 16, an exposure device 17, a developing device 18, a transfer device 19, and a fixing device 30. At the time of image formation, first, the peripheral surface of the photoconductor drum 15 is charged by the charger 16, and then the image data of the document image (for example, the image data of the document image received from an external terminal is displayed on the surface of the photoconductor drum 15 by the exposure device 17. ) Based laser light is irradiated. Then, an electrostatic latent image corresponding to the image data is formed on the surface of the photoconductor drum 15.

The electrostatic latent image formed on the surface of the photosensitive drum 15 is developed by the toner charged in the developing device 18. As a result, a toner image is formed (carried) on the surface of the photosensitive drum 15. This toner image is transferred to the paper P by an application bias having a polarity opposite to that of the toner applied to the transfer roller 19a of the transfer device 19. The paper P is a paper supplied from the paper feed cassette 4a. The sheet P after the toner image is transferred is supplied to the fixing device 30 by the transfer roller 19 a and the photoconductor drum 15.

The fixing device 30 has a heating roller 31 and a pressure roller 32. A heater 31 a is housed inside the heating roller 31 (an example of a heating rotator). The pressure roller 32 (an example of a pressure rotator) is pressed against the heating roller 31 to form the nip portion N. When the paper P passes through the nip portion N, the heating roller 31 and the pressure roller 32 heat and press the paper P, and the toner image on the paper P is melted and fixed on the paper P. To be done. The paper P on which the toner image is fixed is sent to the downstream side by the heating roller 31 and the pressure roller 32, and is discharged to the paper discharge unit 5 by the plurality of transport roller pairs 8 and 9.

[Structure of the fixing device 30]
Next, details of the fixing device 30 will be described with reference to FIGS. The fixing device 30 includes a housing 33 that houses a heating roller 31 and a pressure roller 32. The housing 33 has a rectangular box shape that is long in the front-rear direction. A receiving port 33a (see FIG. 3) for receiving the sheet P conveyed along the sheet conveying path 6 is formed on the lower surface of the housing 33, and a sheet discharge port 33b for discharging the sheet P is formed on the upper surface of the housing 33. Has been done.

The heating roller 31 transfers heat to the paper P on which the toner image is transferred. The heating roller 31 is rotatably supported by a bearing portion (not shown) provided on the inner wall surface of the housing 33. The heating roller 31 is formed of a metal such as a tubular stainless steel. The heater 31a is composed of, for example, a halogen lamp, and is provided inside the heating roller 31. The heater 31a heats the heating roller 31 from the inside. The heater 31a is not limited to the halogen lamp, but may be a ceramic heater or an IH heater.

The pressure roller 32 is arranged parallel to the heating roller 31. The pressure roller 32 is pressed against the pressure roller 32 by an urging member (not shown), and forms a nip portion N between the pressure roller 32 and the heating roller 31 through which the paper P passes. The pressure roller 32 has a cylindrical core metal such as stainless steel, an elastic layer of, for example, silicon rubber formed on the core metal, and a layer made of fluororesin or the like covering the surface of the elastic layer of silicon rubber. ing.

[Configuration of housing 33]
As shown in FIGS. 2 and 3, the housing 33 includes a left housing portion 33c and a right housing portion 33d. The left housing portion 33c is formed so as to cover the heating roller 31, and the right housing portion 33d is formed so as to cover the pressure roller 32. The receiving port 33a and the discharge port 33b are formed at the boundary position between the left housing part 33c and the right housing part 33d.

The left housing portion 33c is composed of a frame member 33e (an example of a bracket member) and a cover member 33f. FIG. 3 shows a state in which the cover member 33f is removed. The frame member 33e is arranged on the left side of the heating roller 31 and extends over the entire axial direction of the heating roller 31. An electric device such as a thermostat 40 described later is attached to the frame member 33e. The cover member 33f covers the entire frame member 33e from the left side so that these electric devices are not exposed to the outside.

FIG. 4 is a side view of the frame member 33e viewed from the left side. Two thermostats 40 for preventing an excessive temperature rise of the heating roller 31 are attached to the frame member 33e. The two thermostats 40 are attached to the frame member 33e at intervals in the front-rear direction. Each thermostat 40 is arranged in the middle of the wiring 50 that connects the heater 31a and the power source, and shuts off the energization path to the heater 31a when the surface temperature of the heating roller 31 reaches a predetermined temperature.

The wiring 50 has a first wiring 50a, a second wiring 50b, and a third wiring 50c. The first wiring 50a connects the power supply unit (not shown) to the rear thermostat 40, the second wiring 50b connects the two thermostats 40, and the third wiring 50c connects the front thermostat 40 and the heater 31a. Are routed to connect. In the following description, when it is not necessary to distinguish the wirings 50a to 50c, the subscripts a to c are omitted and the wirings are referred to as wirings 50.

A flat rectangular mounting seat 33g is formed in a portion of the frame member 33e to which each thermostat 40 is mounted. Each mounting seat portion 33g is formed on the surface of the vertical plate portion 33h of the frame member 33e.

As shown in FIG. 3, each mounting seat 33g (only one of which is shown in FIG. 3) has a through hole 33i for mounting the thermostat 40. The thermostat 40 is fixed to the frame member 33e while penetrating the through hole 33i. Details of the fixing structure of the thermostat 40 will be described later.

[Structure of Thermostat 40]
As shown in FIGS. 5 and 6, the thermostat 40 has a thermostat case 41, a mounting flange portion 42, and a pair of terminal connecting plates 43 (an example of a terminal connecting portion).

The thermostat case 41 is formed in a substantially cylindrical shape as a whole. More specifically, the thermostat case 41 is composed of a case head 41a and a case body 41b. The case head 41a has a diameter slightly larger than that of the case body 41b. The thermostat 40 is arranged such that the end surface of the case head 41 a faces the peripheral surface of the heating roller 31.

The mounting flange portion 42 projects radially outward from the peripheral surface of the thermostat case 41. The mounting flange portion 42 is formed at a boundary position between the case head 41a and the case body 41b. The outer peripheral surface of the case body 41b corresponds to a surface portion of the outer peripheral surface of the thermostat case 41 on the proximal end side of the mounting flange portion 42. An engagement mounting portion 61 of an insulating member 60 described later is mounted on the outer peripheral surface of the case body 41b.
As shown in FIG. 6, the mounting flange portion 42 is formed in a rhombus shape when viewed from the axial direction of the thermostat case 41. A pair of mounting holes 42a are formed at both ends of the mounting flange portion 42 in the longer diagonal direction. The mounting flange portion 42 is fixed to the frame member 33e by a screw 52 inserted into each mounting hole 42a.

The pair of terminal connection plates 43 are made of a conductive metal material. The pair of terminal connection plates 43 extend in opposite directions from the base end of the case body 41b (thermostat case 41). The pair of terminal connection plates 43 are located on the same straight line when viewed in the axial direction of the case body 41b. A fitting hole 43a is formed in the center of the terminal connecting plate 43.

The pair of terminal connection plates 43 is connected to the wiring 50 via a crimp terminal 51 (an example of a wiring terminal). The crimp terminal 51 is caulked and fixed to the end of the wiring 50. As shown in FIG. 6, the crimp terminal 51 has an insertion portion 51a composed of a pair of U-shaped bent pieces. A cylindrical protrusion 51 b is formed in the center of the crimp terminal 51. The crimp terminal 51 is connected to the terminal connection plate 43 by fitting the projection 51b into the fitting hole 43a of the terminal connection plate 43 in a state where the terminal connection plate 43 is inserted into the insertion portion 51a. ing.

FIG. 7 is a schematic diagram showing the internal structure of the thermostat 40. A plate-shaped biometal 44 is accommodated in the case head 41 a of the thermostat case 41. When the temperature of the heating roller 31 is within a predetermined range, the biometal 44 is curved so that the central portion in the longitudinal direction bulges outward from the case with respect to both ends. One end of the pressing pin 35 is in contact with one side surface of the biometal 44 in the thickness direction. The pressing pin 45 is arranged at the center of the thermostat case 41. The other end of the pressing pin 45 is in contact with one of the terminal connecting plates 43 in the case body 41b. One terminal connecting plate 43 is connected to the other terminal connecting plate 43 via a contact 43b. When the temperature of the heating roller 31 exceeds a predetermined temperature due to a mechanical failure or the like, the central portion in the longitudinal direction of the biometal 44 is displaced to the left side (indicated by a white arrow) in FIG. 7. As a result, the contact 43b of the one terminal connecting plate 43 is separated from the other terminal connecting plate 43. As a result, the conduction between the pair of terminal connection plates 43 is cut off, and the power supply from the power supply unit to the heater 31a is also cut off.

[Fixed structure of thermostat 40]
As shown in FIGS. 3 and 5, the thermostat 40 is fixed to the mounting seat portion 33g via the mounting flange portion 42 in a state where the case head 41a penetrates the through hole 33i of the frame member 33e.
As shown in FIG. 8, the mounting flange portion 42 is fixed to the mounting seat portion 33g by a screw 52 inserted through the pair of mounting holes 42a.

[Insulation structure of thermostat 40]
In FIG. 8, the insulating member 60 is omitted in order to facilitate understanding of the fixing structure of the thermostat 40, but in reality, as shown in FIG. 9, the insulating member 60 is mounted around the thermostat 40. It By mounting the insulating member 60 on the thermostat 40, sufficient insulation can be secured even when the insulating distance of the thermostat 40 does not satisfy the specified value.

That is, when the thermostat 40 is installed, it is required to secure the required insulation distance defined by international safety standards. An example of the insulation distance is a spatial distance. This space distance corresponds to the distance L between the mounting flange portion 42 and the crimp terminal 51 shown in FIG. FIG. 10 is a table showing the required insulation distance for each voltage specified in IEC60950-1, which is an example of the international safety standard, and FIG. 11 is a table showing the correction coefficient for each elevation of the required insulation distance. Based on this standard, for example, when the space distance L (hereinafter referred to as the required insulation distance) when reinforced insulation is required at an altitude of 3500 m at a voltage of 200 V is calculated, it becomes 4.0×1.22=4.88 mm, which is a decimal fraction. Since the second place is rounded up, the required insulation distance is 4.9 mm.
Even if this required insulation distance cannot be secured, the insulation structure is considered to be reinforced insulation by disposing an insulator having a thickness of 0.4 mm or more between the crimp terminal 51 and the mounting flange portion 42. Meet safety standards. Therefore, in this embodiment, the insulating member 60 is attached to the thermostat 40.

[Details of Insulation Member 60]
Details of the insulating member 60 will be described with reference to FIGS. 12 to 14. The insulating member 60 is made of an insulating resin material (plastic or the like). The insulating member 60 has an engagement mounting portion 61, a pair of insulating plate portions 62, and a pair of rotation restricting portions 63.

The engagement mounting portion 61 is detachably engaged with the outer peripheral surface of the case body 41b of the thermostat case 41. The engagement mounting portion 61 has a shape in which a part of the cylindrical shape in the circumferential direction is opened outward in the radial direction.

More specifically, the engagement mounting portion 61 has an arcuate tubular portion 61a and a pair of flat plate portions 61b. The arcuate tubular portion 61a is formed such that the inner peripheral surface thereof fits the outer peripheral surface of the case body 41b. The inner diameter dimension D (see FIG. 13) of the arcuate tubular portion 61a is slightly larger than the outer diameter of the case body 41b of the thermostat case 41.

The engagement mounting portion 61 is mounted on the case main body 41b from the outside in the radial direction through the open portion K between the both ends in the circumferential direction of the arcuate tubular portion 61a. In the following description, this mounting direction is defined as the X direction, and the direction orthogonal to both the axial direction of the arcuate tubular portion 61a and the X direction is defined as the Y direction.

The pair of flat plate portions 61b slightly project outward in the X direction from both circumferential ends of the arcuate tubular portion 61a. Then, the pair of flat plate portions 61b function as mounting guides when mounting the arcuate tubular portion 61a on the case body 41b. The inner edges 61c of the pair of flat plate portions 61b are chamfered in order to improve the guide property.

The width W of the open portion K of the arcuate tubular portion 61a (the distance between the pair of flat plate portions 61b) is smaller than the outer diameter of the case body 41b. The arcuate tubular portion 61a has elasticity and is configured to widen the width of the open portion K by applying an external force. Then, the width of the open portion K is increased, so that the arcuate tubular portion 61a can be attached to the case body 41b. After the mounting is completed, the width of the opening portion K of the arcuate tubular portion 61a returns to the original width dimension W by the elastic restoring force. As a result, the arcuate tubular portion 61a is attached to the case body 41b so as not to fall off.

As shown in FIGS. 12 and 14, the engagement mounting portion 61 is provided with a defective portion 61d on one end surface in the axial direction. The defective portion 61d is formed to avoid interference between the engagement mounting portion 61 and the screw 52. The depth dimension h of the defective portion 61d is larger than the protruding height of the head of the screw 52. The defective portion 61d is formed only in a portion where interference between the engagement mounting portion 61 and the screw 52 becomes a problem. An inclined surface 61e is formed at the end of the missing portion 61d on the open portion K side. The inclined surface 61e is formed so that the depth dimension h decreases as it approaches the open portion K. The inclined surface 61e functions to ride on the head of the screw 52 and facilitate the removal work when the engagement mounting portion 61 is removed from the case body 41b.

The pair of insulating plate portions 62 are formed in a rectangular plate shape that protrudes outward in the Y direction from both ends in the Y direction of the engagement mounting portion 61. Each insulating plate portion 62 is connected to an outer peripheral surface (an example of an outer wall surface) of the engagement mounting portion 61 near one end in the axial direction. Each insulating plate portion 62 is formed perpendicular to the axial direction of the engagement mounting portion 61. The thickness of each insulating plate portion 62 is set to, for example, 0.4 mm or more based on international safety standards. As shown in FIG. 14, a rib 62a extending in the Y direction is provided at the center of the lower surface of each insulating plate portion 62 in the X direction.

The pair of rotation restricting portions 63 are formed in a rectangular plate shape. Each rotation restricting portion 63 extends at a right angle from the edge of each insulating plate portion 62 on the side opposite to the open portion K side when viewed from the Y direction. Each rotation restricting portion 63 is also connected to the outer peripheral surface of the engagement mounting portion 61. Each rotation restricting portion 63 extends over substantially the entire axial direction of the engagement mounting portion 61 when viewed from the Y direction.

[Mounting procedure of insulating member 60]
A procedure for mounting the insulating member 60 on the thermostat 40 will be described with reference to FIG. 15.
The insulating member 60 is attached to the case main body 41b of the thermostat case 41 from above (an example of the outside in the radial direction). At this time, since the protective wall 33k becomes an obstacle, the insulating member 60 is actually inserted into the space S between the pair of crimp terminals 51 and the protective wall 33k while being slightly inclined in the direction perpendicular to the paper surface of FIG. Then, the engagement mounting portion 61 of the insulating member 60 is pressed against the outer peripheral surface of the case body 41b from the open portion K side. By further pushing the engagement mounting portion 61 downward from this state, the engagement mounting portion 61 is elastically deformed and the width of the opening portion K is widened, and the engagement mounting portion 61 is mounted on the case body 41b. When the mounting of the engagement mounting portion 61 is completed, the width of the opening portion K returns to the original width dimension W by the restoring force, and the engagement mounting portion 61 is held on the outer peripheral surface of the case body 41b so as not to fall off.

As shown in FIGS. 9 and 16, in the state where the engagement mounting portion 61 is completely mounted to the case body 41b, the pair of insulating plate portions 62 are positioned between the crimp terminals 51 and the mounting flange portion 42, respectively. To do. Therefore, even if the clearance L (see FIG. 5) is less than the required insulation distance defined by the international safety standard, the insulation of the thermostat 40 can be sufficiently ensured. In addition, in the state where the mounting of the engagement mounting portion 61 to the case body 41b is completed, the pair of rotation restricting portions 63 respectively come into contact with the side surface (one side surface in the width direction) of the crimp terminal 51. Therefore, it is possible to prevent the insulating member 60 from unintentionally rotating around the axis of the thermostat case 41. As a result, it is possible to prevent the insulating plate portion 62 from being separated from between the crimp terminals 51 and the mounting flange portion 42 and impairing the insulating property of the thermostat 40.

[Effect]
As described above, according to the present embodiment, the insulating member 60 includes the engagement mounting portion 61 that engages with the case body 41b of the thermostat case 41 and the pair of protrusions from the outer peripheral surface of the engagement mounting portion 61. Each of the crimp terminals 51 connected to the terminal connection plate 43 and the pair of insulating plate portions 62 located between the mounting flange portion 42 are provided.

According to this configuration, when the space distance L of the thermostat 40 is less than the required insulation distance, the insulation of the thermostat 40 can be ensured by an inexpensive configuration without changing the configuration of the thermostat 40 itself. Therefore, even if the required insulation distance cannot be ensured due to, for example, a review of international safety standards, the insulation can be secured by simply attaching the insulating member 60 to the existing thermostat 40 afterwards. Therefore, the cost can be reduced as compared with the case where the thermostat 40 is newly designed and manufactured.

Further, the engagement mounting portion 61 has an arc shape having an opening portion K in a part in the circumferential direction when viewed from the axial direction, and is mounted on the outer peripheral surface of the case body 41b from the outside in the radial direction through the opening portion K. Is configured to.

With this configuration, for example, when the space distance L becomes insufficient due to a change in safety standard after the assembly of the thermostat 40 to the frame member 33e is completed, an insulating member is attached to the case body 41b of the thermostat 40. Insulation can be secured simply by mounting 60 later. Therefore, it is possible to flexibly respond to sudden changes in safety standards and reduce costs.

Further, the width dimension W of the open portion K of the engagement mounting portion 61 is set smaller than the outer diameter dimension of the case body 41b of the thermostat 40. The engaging mounting portion 61 is elastically deformed when mounted on the case body 41b so that the width of the opening portion K is widened, and after the mounting is completed, the elastic deformation is eliminated to open the opening portion K. Is configured to return to the width dimension W before the mounting is completed.

According to this configuration, the engagement mounting portion 61 can be pressed and engaged with the outer peripheral surface of the case body 41b through the opening portion K. Therefore, the insulating member 60 can be easily attached to the thermostat 40 without using a bolt or the like.

Further, the engagement mounting portion 61 is provided with a cutout portion 61d on a surface thereof facing the mounting flange portion 42 of the thermostat 40 so as to avoid interference with the mounting screw 52.

With this configuration, the insulating member 60 can be attached to the thermostat 40 even after the tightening process of the screw 52 is completed. Therefore, the cost can be reduced as compared with the case where the newly designed thermostat 40 is reassembled.

Further, the insulating member 60 has a pair of rotation restricting portions 63. Each rotation restricting portion 63 laterally abuts the crimp terminal 51 connected to each terminal connecting plate 43 of the thermostat 40, so that the engagement mounting portion 61 rotates about the axis of the case body 41b. Is being blocked.

According to this configuration, it is possible to prevent the insulating plate portion 62 from unintentionally rotating due to mechanical vibration or the like and the insulating plate portion 62 from coming off the insulating position.

<<Other Embodiments>>
In the above embodiment, the example in which the insulating member 60 is applied to the thermostat 40 for preventing the excessive temperature rise of the heating roller 31 of the fixing device 30 has been shown, but the present invention is not limited to this. The device to which the thermostat 40 is applied may be, for example, a cooling water circulating device mounted on an engine of an automobile.

Further, in the above embodiment, the insulating main body is configured by the insulating plate 62 having a plate shape, but the shape of the insulating main body is not limited to the plate shape, and may be, for example, a spherical shape or a columnar shape.

Further, in the above-described embodiment, the rotation restricting portion 63 is formed in a plate shape, but the shape is not limited to this, and any shape may be used as long as it makes contact with the crimp terminal 51 from the side. It may be.

Further, in the above-described embodiment, an example in which two thermostats 40 are arranged in the energization path has been shown, but the present invention is not limited to this, and the number of thermostats 40 may be one, or three or more. May be.

As described above, the present invention is useful for a thermostat insulating member, a fixing device, and an image forming apparatus.

K: Opening part P: Paper (recording medium)
W: Width dimension 1: Image forming device 30: Fixing device 31: Heating roller (heating rotating body)
31a: Heater 32: Pressure roller (pressurized rotating body)
33e: Frame member (bracket member)
33i: Through hole 40: Thermostat 41: Thermostat case 42: Mounting flange part 43: Terminal connection plate (terminal connection part)
51: Crimp terminal (wiring terminal)
52: Screw 60: Insulating member 61: Engagement mounting part 61d: Missing part 62: Insulating plate part 63: Rotation restricting part

Claims (7)

An insulating member attached to the thermostat,
The thermostat includes a substantially cylindrical thermostat case, a mounting flange portion that projects radially outward from the outer peripheral surface of the thermostat case, and a pair of wire terminals that are provided at the base end portion of the thermostat case and to which wiring terminals are connected. A terminal connection portion, and in a state where the thermostat case is inserted into a through hole formed in a bracket member, is fixed to the bracket member via the mounting flange portion,
An engagement mounting portion that detachably engages with a surface portion of the outer peripheral surface of the thermostat case on the base end side of the mounting flange portion,
Projecting from the outer wall surface of the engagement mounting portion, an insulating main body portion configured to cut off between each wiring terminal connected to the pair of terminal connection portions and the mounting flange portion, Insulation member. The insulating member according to claim 1,
The engagement mounting portion has an arc shape having an opening in a part of the circumferential direction when viewed from the axial direction, and is mounted from the outside in the radial direction to the surface portion of the thermostat case on the base end side through the opening. An insulating member configured to. The insulating member according to claim 2,
The width dimension of the open portion is smaller than the outer diameter dimension of the thermostat case,
The engagement mounting portion elastically deforms when mounted on the surface portion of the thermostat case on the base end side so that the width of the opening portion widens, and the elastic deformation disappears after the mounting is completed. An insulating member configured as follows. The insulating member according to claim 2,
The mounting flange portion is fixed to the bracket member by a screw penetrating the mounting flange portion,
On the surface of the engagement mounting portion facing the mounting flange portion, a defect portion for avoiding interference with the screw in a state where the engagement mounting portion is mounted on the surface portion on the base end side of the thermostat case. An insulating member provided with. The insulating member according to any one of claims 1 to 4,
Further provided is a pair of rotation restricting portions that abut on the wiring terminals connected to the pair of terminal connecting portions from the side and prevent the engagement mounting portion from rotating around the axis of the thermostat case. Insulating member. A fixing device comprising the insulating member according to claim 1.
The thermostat to which the insulating member is attached,
The bracket member,
A heating rotator heated by a heater,
A heating rotary body that is pressed against the heating rotary body to form a nip portion through which the recording medium passes between the heating rotary body and
The fixing device, wherein the thermostat is configured to cut off the power supply to the heater when the temperature of the heating rotator reaches a predetermined temperature. An image forming apparatus comprising the fixing device according to claim 6.

Images