Internal mixer

Abstract

An internal mixer comprises a mixing chamber having a mixing compartment, a material inlet portion having an internal space, a hopper provided in the material inlet portion, an exhaust passage having an exhaust port provided in the material inlet portion, and a drive device that raises and lowers a weight. The drive device can stop the weight in a lower position where the weight, after entering the upper opening of the mixing compartment, can press the material to be mixed from above, and in an exhaust adjustment position where the weight closes part of the exhaust port. When the weight is in the lower position, a gap is formed between the weight and the peripheral edge of the mixing chamber defining the upper opening.

Description

Title of the invention: Internal mixer FIELD OF INVENTION

[0001] The present invention relates to an internal mixer. PREVIOUS ART

[0002] Conventionally, as described in Japanese public patent application No. 2013-107025, Japanese public patent application No. 2007-118387, and Japanese public patent application No. Hei 4-16223, an internal mixer is known to comprise a mixing chamber having a mixing compartment, a material inlet portion located above the mixing chamber, and a weight disposed in the material inlet portion so as to be able to move up and down to the mixing compartment of the mixing chamber. In this type of mixer, the material to be mixed is blended while the material to be blended is pressed from above by the weight into the mixing compartment.

[0003] A mixer described in publicly available Japanese patent application No. 2013-107025 is used in a mixing process in which a material to be mixed, such as rubber or plastic, and a powder mixing agent are placed together in a mixing compartment to mix the material. In this mixer, a feed door, a powder chute, and a vent chute are connected to a material inlet located above the mixing chamber. The feed door is configured so that it can be opened and closed to introduce the material to be mixed. The powder chute is used when the powder mixing agent for mixing is provided. An inflatable bag with a filter body is integrated into the vent chute.The presence of the ventilation chute prevents the dust-containing gas accompanying the powder mixing agent from being dispersed outside.

[0004] In the mixer described in publicly available Japanese patent application No. 2007-118387, a hopper door, a gas supply device, and a dust collection duct are provided in a material inlet section. The hopper door is opened when the material to be mixed is introduced. The gas supply device is configured to supply inert gas to the material inlet section. The dust collection duct is equipped with a dust collector. By introducing the inert gas into the mixing compartment using the gas supply device, the dust is collected by the dust collector through the dust collection duct. Thus, the particle concentration in the mixing compartment can be reduced.

[0005] The mixer described in publicly available Japanese patent application No. Hei 4-16223 is provided with a cylinder extending upwards from a material inlet portion having a hopper door. The weight is configured to rise relative to the material inlet portion in the cylinder. The space in the cylinder above the weight is a backpressure chamber, and the cylinder is provided with a dust collector that collects the dust contained in the pressurized air in the backpressure chamber.

[0006] In the internal mixer described in publicly available Japanese patent application No. 2013-107025, since the ventilation chute is provided in the material inlet, the dust-containing gas accompanying the powder mixing agent stirred in the material inlet can be collected by the ventilation chute. However, due to the suction force exerted by the ventilation chute, some of the powder mixing agent supplied by the powder chute may be drawn into the ventilation chute. In the internal mixer described in publicly available Japanese patent application No. 2007-118387, the powdered additive introduced into the material inlet can be drawn into the dust collection duct.The dust collector described in publicly available Japanese patent application No. Hei 4-16223 includes a dust collector that collects dust contained in the pressurized air in the backpressure chamber. However, the hopper frame with the hopper door is not provided with a chute or similar element for drawing in the gas.

[0007] Furthermore, neither publicly available Japanese patent application No. 2013-107025, nor publicly available Japanese patent application No. 2007-118387, nor publicly available Japanese patent application No. Hei 4-16223 suggests a measure to deal with the case where the internal pressure in the mixing compartment can be increased by steam generated from the material to be mixed during the mixing of the material to be mixed. SUMMARY OF THE INVENTION

[0008] The object of the present invention is to provide an internal mixer capable of suppressing an increase in internal pressure in a mixing compartment during mixing, and of suppressing the evacuation of a powdery material contained in a material to be mixed introduced into a material inlet portion.

[0009] An internal mixer according to one aspect of the present invention comprises: a mixing chamber having a mixing compartment with an opening at the top; a material inlet portion located above the mixing chamber and having an internal space communicating with the mixing compartment; a hopper that can be opened and closed, provided on a side wall of the portion material inlet and configured so as to be able to introduce a material of a material to be mixed into the interior space of the material inlet part; an exhaust passage connected to another side wall so as to communicate with the interior space via an exhaust orifice formed on the other side wall of the material inlet part; a weight provided in the interior space;a drive device configured to generate a drive force to raise and lower the weight and to be able to stop the weight at a lower position and at an exhaust adjustment position, the lower position being a position where the weight enters an upper opening of the mixing compartment while the weight is able to press the material to be mixed into the mixing compartment from above, and the exhaust adjustment position being located above the lower position and closing at least the exhaust orifice by the weight;and a pair of mixing rotors configured to knead the material to be mixed in the mixing compartment. The weight has a shape that forms a gap between the weight and a peripheral edge defining the upper opening of the mixing compartment, so that a gas generated from the material to be mixed can be vented from the mixing compartment into the interior space when the weight is in the lower position. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] [Fig. 1] The [Fig. 1] is a cross-sectional view illustrating an internal mixer according to the present embodiment, in which a weight is in an exhaust adjustment position and a hopper is in an open state. [Fig.2] Fig.2 is a cross-sectional view illustrating the internal mixer according to the present embodiment in which the weight is in a lower position and the hopper is in a closed state. [Fig.3] Fig.3 is a cross-sectional view illustrating the internal mixer according to the present embodiment, in which the weight is in the exhaust adjustment position and the hopper is in the closed state. [Fig.4] The [Fig.4] is a diagram intended to explain a recess planned on a lateral surface of a weight. [Fig.5] The [Fig.5] is a diagram intended to explain the configuration of a top surface of a weight. [Fig.6] The [Fig.6] is a cross-sectional view illustrating an internal mixer according to a modification. [Fig.7] The [Fig.7] is a diagram intended to explain an opening allowing outside air to be introduced into an interior space. [Fig.8] The [Fig.8] is a diagram intended to explain an inlet port allowing compressed air to be introduced into the interior space. DETAILED DESCRIPTION

[0011] In what follows, embodiments of the present invention will be described in detail with reference to the drawings.

[0012] As illustrated in [Fig.1], an internal mixer 50 according to the present embodiment is a device for mixing a material to be mixed 5 such as rubber or resin, and comprises a mixing chamber 1 having a mixing compartment 2 with an open upper part, and a material inlet part 6 located above the mixing chamber 1. In other words, the mixing compartment 2 has a top opening 2a.

[0013] The mixing compartment 2 is a compartment intended for mixing the material to be mixed 5, and a pair of mixing rotors 3A and 3B is arranged in the mixing compartment 2. The rotors of the pair of mixing rotors 3A and 3B are arranged parallel to each other and can rotate in the mixing compartment 2. Each of the mixing rotors 3A and 3B is driven and rotated by a motor (not shown) located outside the mixing chamber 1. The pair of mixing rotors 3A and 3B is driven to mix the material to be mixed 5 in the mixing compartment 2.

[0014] A discharge port 4 for discharging the mixed material 5 is provided in a lower part of the mixing chamber 1. The discharge port 4 is closed when the mixed material 5 is being mixed, and is opened by a discharge instruction.

[0015] The material inlet portion 6 is cylindrical in shape with a rectangular cross-section. In other words, the material inlet portion 6 comprises a pair of side walls facing each other in one direction and another pair of side walls facing each other in a direction orthogonal to said one direction. The material inlet portion 6 is hollow, and the interior space 16 of the material inlet portion 6 communicates with the mixing compartment 2 through the upper opening 2a.

[0016] The material inlet part 6 is provided with a hopper 10 allowing the material to be mixed 5 to be introduced into the internal space 16, and an exhaust passage 9 allowing a gas, such as steam, to be evacuated from the mixing compartment 2.

[0017] The hopper 10 is provided on a side wall (first side wall 6a) of the material inlet portion 6. The hopper 10 is configured to open and close an opening 17 (or a feed orifice) formed in the first side wall 6a. In other words, the hopper 10 is arranged so that its lower part is positioned at the level of the lower edge of the opening 17, and a hinge 18 is provided at the lower part of the hopper 10. Thus, the hopper 10 can rotate around the axis of the hinge 18 located at the bottom. When the hopper 10 rotates, the opening 17 opens and closes. In other words, the hopper 10 is of the opening / closing type. When the opening 17 is opened by the hopper 10, the material to be mixed 5 can be introduced into the internal space 16 of the material inlet 6.

[0018] The exhaust passage 9 is connected to a side wall (second side wall 6b) different from the first side wall 6a provided with the hopper 10. In other words, an exhaust port 19 is opened in the second side wall 6b, and the exhaust passage 9 is connected to the second side wall 6b so as to communicate with the interior space 16 via the exhaust port 19. In the present embodiment, the second side wall 6b is a side wall facing the first side wall 6a, but it may be a side wall adjacent to the first side wall 6a.

[0019] The exhaust passage 9 extends obliquely upwards from the exhaust port 19. For example, the exhaust passage 9 extends at an angle of 40 to 50 degrees to the vertical. The lower edge of the exhaust port 19 is located higher than the lower edge of the opening 17 (or the feed port) in the first side wall 6a. Consequently, it is possible to prevent the material introduced from the hopper 10 from flowing directly into the exhaust passage 9. Even if the swirling powdered material in the internal space 16 enters the exhaust passage 9, the material may fall into the mixing compartment 2, thus preventing the exhaust port 19 from becoming blocked.

[0020] A suction machine 21 is provided in the exhaust passage 9. By operating the suction machine 21, the gas (including dust or similar in some cases) in the internal space 16 of the material inlet part 6 can be evacuated to the outside of the internal mixer 50 through the exhaust passage 9.

[0021] A weight 7 is disposed in the internal space 16 of the material inlet portion 6 so as to be able to move up and down. The weight 7 is connected to a drive device 23 for moving the weight 7 up and down by means of a connecting rod 8.

[0022] The drive device 23 generates a drive force to raise and lower the weight 7. The drive device 23 comprises, for example, a cylinder (not shown) and a piston (not shown) arranged slidably in the cylinder, and can be configured to move the weight 7 in the vertical direction via the connecting rod 8 by a reciprocating motion of the piston.

[0023] The drive device 23 is configured to be able to stop the weight 7 at a lower position (position illustrated in [Fig. 2]) and at a position exhaust adjustment (position illustrated in [Fig. 1]). In other words, by controlling the working fluid supplied to the cylinder, the weight 7 can be stopped at the lower position and at the exhaust adjustment position. In this case, for example, a sensor 25 that detects the position of the connecting rod 8 (or the weight 7 or the piston) can be provided, and the drive device 23 can control the stopping position of the weight 7 based on the detection result of the sensor 25. In addition, a stop (not illustrated) for stopping the weight 7 at the exhaust adjustment position can be provided, and in this case, the drive device 23 can raise the weight 7 until it abuts against the stop to stop at the exhaust adjustment position.The drive device 23 can be adjusted so that the upper limit of the displacement range of the weight 7 is at the exhaust adjustment position and the lower limit of the displacement range is at the lower position.

[0024] As illustrated in [Fig. 2], when the weight 7 is in its lower position, it enters the upper opening 2a of the mixing compartment 2. The weight 7 thus presses the material to be mixed 5 into the mixing compartment 2 from above. The drive device 23 applies a downward force to the weight 7 so that the weight 7 can press the material to be mixed 5.

[0025] As illustrated in [Fig. 1], the exhaust adjustment position is a position in which the weight 7 is raised relative to the lower position. When the weight 7 is in the exhaust adjustment position, the upper opening 2a of the mixing compartment 2 is open towards the inner space 16 of the material inlet portion 6. When the weight 7 is in the exhaust adjustment position, substantially half (substantially the upper half) of the exhaust port 19 is closed by the weight 7. However, the weight 7 in the exhaust adjustment position is not limited to the position that blocks substantially half of the exhaust port 19, and it can be any position, as long as it blocks at least a portion of the exhaust port 19.

[0026] The exhaust adjustment position is also the position of the weight 7 when the opening 17 is opened by the hopper 10 to introduce the material. Therefore, it is possible to prevent the material introduced by the hopper 10 from unintentionally flowing into the exhaust passage 9 through the exhaust port 19.

[0027] As illustrated in [Fig. 3], the drive device 23 can position the weight 7 at the exhaust adjustment position when the hopper 10 is closed and the material to be mixed 5 is being mixed in the mixing compartment 2. In other words, if it is not necessary to perform mixing while pressing the material to be mixed 5 with the weight 7 according to the mixing conditions, the drive device 23 can position the weight 7 at the position exhaust adjustment. Even in this case, the weight 7 blocks part of the exhaust orifice 19, so that the powdery material dispersed from the material to be mixed 5 is unable to flow into the exhaust passage 9.

[0028] When the weight 7 is in the lower position, the upper opening 2a of the mixing compartment 2 is substantially closed by the weight 7. At this point, as illustrated in [Fig. 4], a gap 30 is formed between the peripheral edge la (or the inner peripheral surface) defining the upper opening 2a in the mixing chamber 1 and the lateral surface of the weight 7 located in the lower position. Consequently, if the internal pressure of the mixing compartment 2 increases, air (in some cases, introduced powdered material, gas generated from the material to be mixed 5, and the like) in the mixing compartment 2 can escape into the inner space 16 of the material inlet portion 6 through the gap 30.

[0029] In addition, a recess 31 is formed on the lateral surface of the weight 7, and the size of the gap 30 is enlarged by the formation of the recess 31. In other words, the gap 30 is formed between the lateral surface of the weight 7 and the peripheral edge la (or the inner peripheral surface) defining the upper opening 2a, without forming the recess 31 on the lateral surface of the weight 7, and the width of the gap 30 is greater due to the presence of the recess 31.

[0030] As illustrated in [Fig. 4], the recess 31 is provided on a pair of lateral surfaces 7a and 7b facing each other. However, the present embodiment is not limited to this configuration. The recess 31 may be provided on at least one lateral surface, and may be provided on each of the lateral surfaces of the weight 7.

[0031] The recess 31 can be provided on the lateral surface 7a facing the second lateral wall 6b having the exhaust port 19 in the material inlet part 6 among the lateral surfaces of the weight 7. In this case, a gas flowing upwards through the gap 30 between the peripheral edge la (or the inner peripheral surface) of the upper opening 2a and the recess 31 flows directly into the exhaust passage 9 through the exhaust port 19. Therefore, in the case where the powdery material of the gas is confined, the powdery material is easily drawn into the exhaust passage 9.

[0032] As illustrated in [Fig. 5], an upper surface 7c of the weight 7 is inclined. More precisely, the upper surface 7c of the weight 7 is inclined such that the exhaust port side 19 is lower than the hopper side 10. In other words, the height of the lateral surface 7a of the weight 7 facing the second lateral wall 6b is less than the height of a lateral surface 7b of the weight 7 facing the first side wall 6a. Thus, a gas, such as steam, generated in the mixing compartment 2, easily passes through the gap 30 closer to the exhaust port side 19 than through the gap 30 closer to the hopper side 10. Furthermore, if the recess 31 is provided in the side surface 7a of the weight 7 facing the second side wall 6b with the exhaust port 19, a gas, such as steam, can flow more easily through the gap 30 on the exhaust port side 19. In addition, since the upper surface 7c of the weight 7 is inclined, it is possible to prevent the powdery component from accumulating on the upper surface 7c of the weight 7.

[0033] In the internal mixer 50 of the present embodiment having the configuration described above, the material to be mixed 5 is introduced into the mixing chamber 1 from the material inlet 6 with the weight 7 in the exhaust adjustment position. Once the material to be mixed 5 has been introduced, the drive device 23 lowers the weight 7 to the lower position. When the weight 7 reaches the lower position where it enters the upper opening 2a of the mixing compartment 2, the drive device 23 stops lowering the weight 7. At this point, the gap 30 is formed between the peripheral edge la of the upper opening 2a in the mixing chamber 1 and the lateral surface of the weight 7. When the pair of mixing rotors 3A and 3B are driven in this state, the material to be mixed 5 is mixed in the mixing compartment 2.

[0034] During mixing, the moisture, or other substances, contained in the material to be mixed 5 can vaporize to generate steam as the temperature of the material to be mixed 5 increases. This steam can flow into the internal space 16 of the material inlet portion 6 through the gap 30. Therefore, even when the material to be mixed 5, which generates a large amount of steam, is mixed, the increase in internal pressure of the mixing compartment 2 can be suppressed. The gas flowing into the internal space 16 is drawn into the exhaust passage 9 through the exhaust port 19, by the operation of the suction machine 21, and is discharged outside the internal mixer 50. In the event that the gap 30 is obstructed for any reason, a foreign substance can be scraped by a scraper (not shown) or similar, after the weight 7 has been lifted.

[0035] On the other hand, when the drive device 23 operates to lift the weight 7 from the lower position, the drive device 23 stops the weight 7 at the exhaust adjustment position. In this state, the hopper 10 is open and the material (mixable material 5, additives, etc.) from the mixed material 5 can be introduced into the internal space 16 of the material inlet portion 6. At this stage, the suction machine 21 is in the stopped state and at least part of the exhaust orifice 19 is blocked by the weight 7. Thus, in the case where the material to The mixing 5, introduced from the hopper 10, contains a powdery material. Even if the powdery material is projected, it is possible to prevent the powdery material from flowing into the exhaust passage 9 through the exhaust port 19. Therefore, it is possible to prevent the powdery material from being discharged outside the internal mixer 50.

[0036] When the weight 7 is in the exhaust adjustment position, substantially half of the exhaust port 19 is blocked by the weight 7. Therefore, since the exhaust port 19 can be substantially closed while preventing the displacement stroke of the weight 7 from becoming excessive, the overall height of the internal mixer 50 can be reduced while obtaining a configuration in which part of the exhaust port 19 is closed.

[0037] In this embodiment, the recess 31 is provided on the lateral surface 7a located immediately below the exhaust port 19 among the lateral surfaces of the weight 7. Consequently, when the gas generated from the material to be mixed 5 flows out of the mixing compartment 2 through the gap 30 between the recess 31 of the weight 7 and the peripheral edge la (or the inner peripheral surface) defining the upper opening 2a, the gas rises and is guided directly to the exhaust port 19. Therefore, the gas can be efficiently guided to the exhaust passage 9.

[0038] In the present embodiment, the upper surface 7c of the weight 7 is inclined so that the portion on the exhaust port side 19 is lower than the portion on the hopper side 10. Consequently, the thickness of the weight 7 in the vertical direction is thin on the exhaust port side 19 and thick on the hopper side 10. Therefore, a gas, such as steam, can be efficiently guided towards the exhaust port 19 from the exhaust port side 19. In the case where the material to be mixed 5 contains a powdery component, it is possible to prevent the powdery component from accumulating on the upper surface 7c of the weight 7.

[0039] (Other embodiments) It should be understood that the embodiment described herein is illustrative in all respects and is in no way restrictive. The present invention is not limited to the above embodiment, and various modifications, improvements, and other enhancements may be made without departing from the essence of the present invention. For example, as illustrated in [Fig. 6], an opening 33 may be formed in the side wall of the material inlet portion 6 at a position on the upper side of the hopper 10. The opening 33 serves as an intake port to allow outside air into the internal space 16 when the hopper 10 is closed and the suction machine 21 is in operation. When outside air is drawn in through the opening 33, it is possible to prevent gases, such as water vapor and ethanol, from entering the hopper. generated by the material to be mixed 5 to remain in the internal space 16 of the material inlet part 6.

[0040] As illustrated in [Fig. 7], in the material inlet portion 6, an opening 34 may be provided in the second side wall 6b where the exhaust port 19 is formed. This opening 34 also serves as an intake port to allow outside air into the interior space 16 when the suction machine 21 is in operation. Furthermore, a plurality of openings 34 may be provided. In addition, the openings 33 and 34 may be provided on any side wall of the material inlet portion 6. Therefore, for example, the opening 33 in the first side wall 6a and the opening 34 in the second side wall 6b may be provided, or only the opening 34 in the second side wall 6b may be provided.

[0041] As illustrated in [Fig. 8], the material inlet portion 6 can be provided with a compressed air inlet port 35. A pipe (not shown) connected to the compressor (not shown) is connected to the inlet port 35. The compressed air discharged from the compressor is sent into the internal space 16 of the material inlet portion 6 through the inlet port 35. Consequently, when the suction machine 21 is operating, compressed air is sent into the internal space 16, so that the gas present in the internal space 16 can be more easily discharged to the outside through the exhaust passage 9. Thus, the stagnation of the gas generated by the material to be mixed 5 can be prevented more effectively, and forced ventilation can be achieved.The inlet port 35 may be provided in the second side wall 6b where the exhaust port 19 is formed, or may be provided in a side wall other than the second side wall 6b. Furthermore, the number of inlet ports 35 may be arbitrary.

[0042] In the embodiment above, the recess 31 is provided on the lateral surface of the weight 7, but the recess 31 can be omitted as long as the exhaust through the gap 30 between the lateral surface of the weight 7 and the peripheral edge la (or the inner peripheral surface) of the upper opening 2a is sufficient. However, since the recess 31 is formed, the location where the gas is discharged from the mixing compartment 2 can be concentrated, so that the discharge to the outlet 19 can be easily controlled. The recess 31 need not be positioned directly below the outlet 19.

[0043] In the above embodiment, the upper surface 7c of the weight 7 is inclined, but the upper surface 7c of the weight 7 may not be inclined insofar as the material to be mixed 5 does not contain a large quantity of powdery components.

[0044] The embodiments will be described succinctly below.

[0045] The internal mixer according to the embodiment comprises: a mixing chamber having a mixing compartment with an opening at the top; a material inlet portion located above the mixing chamber and having an internal space communicating with the mixing compartment; a hopper that can be opened and closed, provided on a side wall of the material inlet portion and configured so as to be able to introduce material to be mixed into the internal space of the material inlet portion; an exhaust passage connected to another side wall so as to communicate with the internal space through an exhaust orifice formed on the other side wall of the material inlet portion; a weight provided in the internal space;a drive device configured to generate a drive force capable of raising and lowering the weight and of being able to stop the weight at a lower position and at an exhaust adjustment position, the lower position being a position in which the weight enters an upper opening of the mixing compartment while being able to press the material to be mixed into the mixing compartment from above, and the exhaust adjustment position being located above the lower position and closing at least the exhaust orifice by the weight;and a pair of mixing rotors configured to knead the material to be mixed in the mixing compartment. The weight has a shape that forms a gap between the weight and a peripheral edge defining the upper opening of the mixing compartment, so that a gas generated from the material to be mixed can be vented from the mixing compartment into the interior space when the weight is in the lower position.

[0046] In the internal mixer, the material to be mixed is introduced from the material inlet into the mixing chamber with the weight in the exhaust adjustment position. Once the material to be mixed has been introduced, the drive device lowers the weight to the bottom position. When the weight reaches the bottom position, the drive device stops lowering it. At this point, a gap is created between the weight and the peripheral edge of the mixing chamber, which defines the upper opening of the mixing compartment. When the pair of mixing rotors is driven in this state, the material to be mixed is blended in the mixing compartment.

[0047] During mixing, moisture or other substances contained in the material to be mixed can vaporize to generate steam as the temperature of the material increases. This steam can flow into the internal space of the material inlet through the gap. Therefore, even when mixing a material that generates a large amount of steam, the increase in internal pressure of the mixing compartment can be suppressed.

[0048] On the other hand, when the drive device is operating to lift the weight from the lower position, the drive device stops the weight at the exhaust adjustment position. In this state, the hopper is open and the material to be mixed can be introduced into the internal space of the material inlet. At this stage, at least part of the exhaust orifice is blocked by the weight. Therefore, if the material to be mixed introduced from the hopper contains powder, even if the powder is projected, it is possible to prevent the powder from flowing into the exhaust passage. Consequently, it is possible to prevent the discharge of the powder from the internal mixer.

[0049] At least a portion of the exhaust port, when the weight is in the exhaust adjustment position, may substantially correspond to half of the exhaust port.

[0050] In this aspect, the exhaust port can be substantially closed while preventing the weight displacement stroke from becoming excessive. Consequently, it is possible to limit the overall height of the internal mixer while obtaining a configuration in which part of the exhaust port is blocked.

[0051] A recess may be provided on a lateral surface of the weight. In this case, a gap between the recess and the peripheral edge of the mixing chamber may be located below the exhaust port.

[0052] In this aspect, since the width of the gap between the lateral surface of the weight and the peripheral edge of the mixing chamber is enlarged, the gas generated from the material to be mixed can easily flow out of the mixing compartment. Furthermore, the gas flowing out of the mixing compartment through the gap between the recess and the peripheral edge of the mixing chamber can be guided to the exhaust port itself, simply by lifting the gas. In other words, the position from which the gas flows out of the mixing compartment can be easily controlled.

[0053] The other side wall of the material inlet portion having the exhaust port and said side wall of the material inlet portion having the hopper may face each other. In this case, the upper surface of the weight may be inclined so that a portion on the exhaust port side is lower than a portion on the hopper side.

[0054] In this aspect, the thickness of the weight in the vertical direction is thin on the exhaust port side and thick on the hopper side. Therefore, a gas, such as steam, can be efficiently guided to the exhaust port from the exhaust port side. In the case where the material to be mixed contains a powdery component, it is possible to prevent the powdery component from accumulating on the upper surface of the weight.

[0055] A suction machine can be connected to the exhaust passage, and in this case, the material inlet can be provided with an opening capable of introducing outside air into the interior space. In this configuration, outside air can flow into the interior space of the material inlet through the opening when the suction machine is activated to evacuate the gas into the interior space. Consequently, it is possible to easily evacuate the gas from the interior space.

[0056] The material inlet portion may be provided with an inlet orifice through which compressed air can be introduced into the internal space. In this aspect, compressed air can be introduced into the internal space through the inlet orifice. Consequently, when the suction machine is operating, compressed air is sent into the internal space, so that the gas present in the internal space can be more easily expelled to the outside through the exhaust passage. In other words, the gas present in the internal space can be forcibly replaced by compressed air.

[0057] As described above, it is possible to limit the increase in internal pressure of the mixing compartment during mixing, and it is also possible to limit the evacuation of the powdery material contained in the material to be mixed introduced into the material inlet part.

Claims

Demands

1. Internal mixer, comprising: a mixing chamber having a mixing compartment with a top opening; a material inlet portion situated above the mixing chamber and having an internal space communicating with the mixing compartment; a hopper that can be opened and closed, provided on a side wall of the material inlet portion and configured so as to be able to introduce material from a material to be mixed into the internal space of the material inlet portion; an exhaust passage connected to another side wall so as to communicate with the internal space via an exhaust orifice formed on the other side wall of the material inlet portion; a weight provided in the internal space;a drive device configured to generate a drive force enabling the weight to be raised and lowered and to be able to stop the weight in a lower position and in an exhaust adjustment position, the lower position being a position in which the weight enters an upper opening of the mixing compartment while the weight is able to press the material to be mixed into the mixing compartment from above, and the exhaust adjustment position being located above the lower position and closing at least part of the exhaust orifice with the weight;and a pair of mixing rotors configured to knead the material to be kneaded in the mixing compartment, wherein the weight has a shape which forms a gap between the weight and a peripheral edge defining the upper opening of the mixing compartment, so that a gas generated from the material to be kneaded can be vented from the mixing compartment to the interior space when the weight is in the lower position.

2. Internal mixer according to claim 1, wherein at least a portion of the exhaust port when the weight is in the exhaust adjustment position corresponds substantially to half of the exhaust port.

3. Internal mixer according to claim 1, wherein a recess is provided on a lateral surface of the weight, and a gap between the recess and the peripheral edge of the mixing chamber is located below the exhaust port.

4. Internal mixer according to claim 1, wherein the other side wall of the material inlet part having the exhaust port and the side wall of the material inlet part having the hopper face each other, and an upper surface of the weight is inclined so that a part of the exhaust port side is lower than a part of the hopper side.

5. Internal mixer according to claim 1, wherein a suction machine is connected to the exhaust passage, and the material inlet part is provided with an opening through which outside air can be introduced into the internal space.

6. Internal mixer according to claim 5, wherein the material inlet part is provided with an inlet orifice through which compressed air can be introduced into the internal space.

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