JP5516527B2 - Resin gear parts with nuts - Google Patents

Description

  The present invention relates to a resin gear part with a nut in which a metal nut part is inserted into a resin gear part having gear teeth in a predetermined rotation range.

There is a need to rotate integrally a gear part on which gear teeth are formed and a metal part that is required to be provided with a metal material (for example, a cam plate that requires wear resistance and load resistance). .
In this case, if the gear part and the metal part are made of an integral metal, strength and reliability can be obtained, but there is a problem that the cost and weight increase.

Therefore, parts that require high strength are provided with metal parts, gear parts that do not require such high strength are provided with resin, and metal parts are attached to resin gear parts (resin gear parts), thereby reducing costs. It is conceivable to reduce the weight.
In this case, as shown in FIG. 1A, as a means for attaching the metal part to the resin gear part α, a metal nut part β is inserted in advance into the resin gear part α, and the metal part is attached to the resin gear part α. It is conceivable that the metal part is fixed to the resin gear part α by fastening a screw to the nut part β after mounting.

However, when the resin gear part α is injection-molded in the mold (during resin molding), since the molten resin flow {see arrow X in FIG. 1 (a)} wraps around the nut part β, the outer diameter of the nut part β A weld (joint due to the joining of the resin) occurs in the gear teeth 3a on the side, and a problem that the strength of the gear teeth 3a decreases due to the weld.
Further, at the time of resin molding, the spread of the flow of the molten resin {see the broken line Y in Fig. 2 (a)} is obstructed by the nut part β. It becomes easy to occur, and the malfunction that the dimensional accuracy of the gear tooth 3a falls occurs.

JP 2008-150955 A

  The present invention has been made in view of the above problems, and its purpose is to prevent a reduction in gear tooth strength and a reduction in dimensional accuracy even when a metal nut part is inserted into a resin gear part. It is to provide resin gear parts with nuts that can ensure high reliability.

[Means of claim 1]
In the present invention,
-One rotating end of the gear teeth is connected to one gear end A,
-The other rotating end of the gear tooth is connected to the other gear end B,
-The rotation center of the resin gear part is the rotation center C,
-The center of the female thread in the nut part is the nut center D,
-A straight line connecting one gear end A and the rotation center C is a virtual straight line AC,
A straight line connecting the other gear end B and the rotation center C is represented by a virtual straight line B-C,
The range of the resin gear part on the side where the gear teeth are provided divided by the imaginary straight line AC and the imaginary straight line BC is the geared range θa,
The range of the resin gear part on the side divided by the virtual straight line AC and the virtual straight line BC and where no gear teeth are provided is the gear no range θb,
It is defined as

In the resin gear part, the nut center D is not disposed in the geared range θa, but is disposed only in the gearless range θb (the nut center D is on the virtual straight line AC or the virtual straight line B). -Including the case where it is arranged on -C), it is possible to prevent welds from being formed on the gear teeth during resin molding, and it is possible to prevent a reduction in the strength of the gear teeth due to welds.
Further, in the resin gear part, the nut center D is not arranged in the geared range θa and the nut center D is arranged only in the gearless range θb (the nut center D is on the virtual straight line AC or the virtual straight line B). -In the case of resin molding, since the spread of the flow of the molten resin toward the gear teeth is not hindered by the nut parts, the filling failure of the molten resin into the gear teeth is suppressed, and the gear teeth It is possible to prevent a decrease in dimensional accuracy.
Thus, by adopting the means of claim 1, it is possible to prevent a reduction in gear tooth strength and accuracy, and to improve the reliability of the resin gear part with a nut.

[Means of claim 2]
Two or more gates are provided in the geared range θa for pouring the resin into the mold during the injection molding of the resin gear parts.
And
The distance between adjacent gates within the geared range θa is the distance between the gates L,
-A distance 1/2 of the distance L between the gates is defined as a merging distance L1,
The distance from the gate within the gear range θa to the gear bottom of the gear teeth is the gear tooth reach distance L2,
It is defined as
And the means of claim 2 is:
Junction distance L1 <Gear tooth reach distance L2
Satisfies the relationship.

As a result, the molten resin flowing out from the gate in the geared range θa merges with the molten resin flowing out from the gate in the other geared range θa before reaching the gear bottom of the gear teeth. Since the merged molten resin spreads from the inner diameter direction to the outer diameter direction, the gear teeth can be uniformly filled with resin, and a reduction in dimensional accuracy of the gear teeth can be prevented.
Even if a plurality of gates are provided in the geared range θa, since the gear teeth are filled with resin after the molten resin has joined, welds are formed in the gear teeth by the gates provided in the geared range θa. Can be avoided, and a reduction in the strength of the gear teeth due to the weld can be prevented.

[Means of claim 3]
The number of gates in the geared range θa is larger than the number of gates in the gearless range θb.
Thus, during resin molding, resin filling in the geared range θa is fast, and conversely, resin filling in the gearless range θb is slowed. For this reason, the joining point of “the molten resin spreading from within the geared range θa” and “the molten resin spreading from within the gearless range θb” can be within the gearless range θb.
As a result, it is possible to avoid a problem that a weld due to a joining point of “a molten resin extending from within the geared range θa” and “a molten resin extending from within the gearless range θb” is formed on the gear teeth, and the gear by the weld A reduction in tooth strength can be avoided.

[Means of claim 4]
The nut part in the resin gear part with a nut according to claim 4 is screwed with a screw for fixing the metal cam plate in which the cam groove is formed to the resin gear part.

[Means of claim 5]
The resin gear part with a nut according to claim 5 is used as a final gear of a gear reduction device that reduces the rotational output of the electric motor.

[Means of claim 6]
According to a sixth aspect of the present invention, there is provided a resin gear part with a nut having a low pressure EGR adjusting valve for adjusting an opening degree of a low pressure EGR flow path that guides EGR gas to an intake passage through which intake air passes, and an intake air at a junction of the intake passage and the low pressure EGR flow path. It is used for a drive device that drives an intake throttle valve that generates a negative pressure.

It is explanatory drawing of the flow of the molten resin at the time of resin molding of the last gear. It is explanatory drawing of the spread of molten resin at the time of resin molding of the last gear. It is explanatory drawing of the gate in a gear range. It is explanatory drawing of the gate in a gear range and a gear no range. 1 is a schematic view of an intake / exhaust system of an engine. It is a graph which shows the relationship between the EGR flow volume according to the rotation angle of a low pressure EGR regulating valve, and an intake air flow rate. It is explanatory drawing of EGR control in a high voltage / low pressure EGR amount control program. It is the schematic of a low pressure EGR valve unit. It is a top view of the last gear with which the cam plate was assembled | attached.

[Mode for Carrying Out the Invention (Embodiment)] will be described with reference to the drawings.
As a specific example, an example in which the present invention is used for the final gear 3 in the low pressure EGR valve unit 2 of the low pressure EGR device 1 will be described.

The low pressure EGR device 1 is
A low pressure EGR adjustment valve 6 for adjusting the opening degree of the low pressure EGR flow path 5 for introducing EGR gas to the intake passage 4 in the low intake negative pressure generation range;
An intake throttle valve 7 that generates an intake negative pressure at the junction of the intake passage 4 and the low pressure EGR flow path 5 by restricting the intake passage 4;
A driving device for driving the low pressure EGR adjustment valve 6 and the intake throttle valve 7;
Is provided.

The drive device
One electric actuator 8 for driving the low pressure EGR regulating valve 6;
A link device 9 for driving the intake throttle valve 7 by changing the output characteristics of the electric actuator 8,
Consists of.

The electric actuator 8 is
An electric motor 8a that generates rotational torque when energized;
A gear reduction device 8b that reduces the rotational output of the electric motor 8a;
Is a combination.

The link device 9
A cam plate 12 having a cam groove 11 and rotating integrally with the low pressure EGR adjustment valve 6;
A driven arm 14 having a cam groove engaging portion 13 (a roller or the like) that engages with the cam groove 11 and rotating integrally with the intake throttle valve 7;
Is provided.
The rotational torque applied to the cam plate 12 (rotational torque applied to the low pressure EGR adjustment valve 6) is transmitted to the driven arm 14 via the cam groove engaging portion 13 that engages the cam groove 11, thereby The throttle valve 7 is driven.

In this embodiment, the present invention is applied to the final gear 3 (resin gear part with a nut) of the gear reduction device 8b.
The cam plate 12 is made of metal because high strength is required.
On the other hand, the final gear 3 is made of resin because it does not require a very high strength.

The final gear 3 of this embodiment includes a resin gear part α (resin gear part) provided with gear teeth 3a only within a predetermined rotation range, and a plurality ( In the drawing, three metal nut parts β (parts having an internal thread formed on the inner peripheral surface: they may be bottomed or may penetrate). Then, the cam plate 12 is attached to the final gear 3 (the resin gear part α in which the nut part β is molded), and the screw γ is fastened to the nut part β, so that the metal cam plate 12 is made of the resin final gear 3. This is fixed to the resin gear part α in which the nut part β is molded.
In this embodiment, the nut center D inserted into the final gear 3 is arranged only in the gearless range θb. The arrangement range of the nut center D may include at least one on the virtual straight line AC or the virtual straight line BC.

  A specific example (embodiment) in which the present invention is applied to the driving device of the low pressure EGR device 1 will be described with reference to the drawings. The following examples disclose specific examples, and it goes without saying that the present invention is not limited to the examples. In the following embodiments, the same reference numerals as those in the “DETAILED DESCRIPTION OF THE INVENTION” denote the same functional objects.

First, an engine intake / exhaust system will be described with reference to FIGS.
The engine intake / exhaust system is provided with a high pressure EGR device 21 and a low pressure EGR device 1.

The high pressure EGR device 21 includes a high exhaust pressure range (a range where high exhaust pressure is generated on the upstream side of the DPF 22) and a high intake negative pressure generation range (on the intake downstream side of the throttle valve 24). It is an exhaust gas recirculation device that is good at returning a large amount of EGR gas to the engine by connecting the inside of the intake passage 4 in a range where high intake negative pressure is generated), and a part of the exhaust gas is EGR gas. As a high pressure EGR flow path 25 returning to the intake downstream side of the intake passage 4.
As a specific example, the high-pressure EGR flow path 25 of FIG. 5 is connected to the exhaust manifold 23 on the exhaust passage 23 side and connected to the intake manifold (FIG. 5 is a surge tank 26 of the intake manifold) on the intake passage 4 side.

The high-pressure EGR device 21 shown in FIG. 5 includes a high-pressure EGR adjustment valve 27 that adjusts the flow rate of the EGR gas by adjusting the opening of the high-pressure EGR passage 25 in the middle of the high-pressure EGR passage 25, and The high pressure EGR cooler 28 that cools the returned EGR gas, the high pressure cooler bypass 29 that bypasses the EGR gas returned to the intake side from the high pressure EGR cooler 28, and the high pressure EGR that switches between the high pressure EGR cooler 28 and the high pressure cooler bypass 29. A cooler switching valve 30 is provided.
FIG. 5 is a specific example, and the high pressure EGR cooler 28, the high pressure cooler bypass 29, and the high pressure EGR cooler switching valve 30 may not be mounted.

The low pressure EGR device 1 includes an exhaust passage 23 in a low exhaust pressure range (a range where low exhaust pressure is generated on the exhaust downstream side of the DPF 22) and a low intake negative pressure generation range (on the intake upstream side of the throttle valve 24). This is an exhaust gas recirculation device that is good at returning a small amount of EGR gas to the engine by connecting to the inside of the intake passage 4 in a range where low intake negative pressure is generated), and part of the exhaust gas is EGR gas. Is provided with a low pressure EGR flow path 5 returning to the intake upstream side of the intake path 4.
As a specific example, the low-pressure EGR flow path 5 of FIG. 5 is connected to the exhaust pipe on the exhaust downstream side of the DPF 22 on the exhaust passage 23 side, and connected to the intake pipe upstream of the compressor 31 of the turbocharger on the intake passage 4 side. Has been.

The low-pressure EGR device 1 includes a low-pressure EGR adjustment valve 6 that adjusts the flow rate of the EGR gas by adjusting the opening degree of the low-pressure EGR flow path 5 in the middle of the low-pressure EGR flow path 5, and an EGR gas that is returned to the intake side. And a low-pressure EGR cooler 32 for cooling the air.
Further, the low pressure EGR device 1 is provided with an intake throttle valve 7 for generating an intake negative pressure at the junction of the intake passage 4 and the low pressure EGR flow path 5.

  The intake throttle valve 7 is provided so as to open a part of the intake passage 4 even when the intake passage 4 is throttled to the maximum. Specifically, even when the intake throttle valve 7 is in a state where the intake passage 4 is throttled to the maximum, for example, about 10% of the intake passage 4 is provided (indicated by a solid line 7 ′ in FIG. 6). Refer to the minimum flow).

Next, the ECU that controls the high-pressure EGR device 21 and the low-pressure EGR device 1 will be described. The ECU is equipped with an EGR control program that controls the operation of the high-pressure EGR device 21 and the low-pressure EGR device 1.
This EGR control program is
A high-pressure EGR cooler switching program for switching the high-pressure EGR cooler switching valve 30 based on the warm-up state of the engine (for example, the temperature of engine cooling water);
A high-pressure / low-pressure EGR amount control program for controlling the opening of the high-pressure EGR adjustment valve 27, the low-pressure EGR adjustment valve 6 and the intake throttle valve 7 according to the engine speed and engine load (engine load torque) is provided.

An outline of the high pressure / low pressure EGR amount control program will be described with reference to FIG.
The high pressure / low pressure EGR amount control program is
・ When the operating range is below the solid line i shown in FIG. 7 (engine operating range based on the relationship between engine speed and engine load torque), the low pressure EGR device 1 is stopped and the opening of the high pressure EGR regulating valve 27 of the high pressure EGR device 21 EGR control is performed only by control (specifically, the low pressure EGR flow path 5 is closed by the low pressure EGR adjustment valve 6 and the high pressure EGR adjustment valve 27 is controlled to an opening degree corresponding to the relationship between the engine speed and the engine load torque. )
In the operation region between the solid line i and the solid line ii shown in FIG. 7, the opening degree control of the high pressure EGR adjustment valve 27 of the high pressure EGR device 21 and the low pressure EGR adjustment valve 6 and the intake throttle valve 7 of the low pressure EGR device 1 are controlled. EGR control is performed by both opening degree control (specifically, the high pressure EGR adjustment valve 27 is controlled to an opening degree according to the relationship between the engine speed and the engine load torque, and the low pressure EGR adjustment valve 6 and the intake throttle valve are controlled. 7 is controlled to an opening corresponding to the relationship between the engine speed and the engine load torque),
-In the operating region above the solid line ii shown in FIG. 7, the high pressure EGR device 21 is stopped, and EGR control is performed only by opening control of the low pressure EGR adjustment valve 6 and the intake throttle valve 7 of the low pressure EGR device 1 (specifically The high-pressure EGR flow path 25 is closed by the high-pressure EGR adjustment valve 27, and the low-pressure EGR adjustment valve 6 and the intake throttle valve 7 are controlled to an opening degree corresponding to the relationship between the engine speed and the engine load torque). is there.

The low-pressure EGR device 1 is good at returning a small amount of EGR gas to the engine because it returns the EGR gas in the low exhaust pressure range to the low intake negative pressure generation range. However, even if there is an operation region where a large amount of EGR gas is desired to be returned to the engine using the low pressure EGR device 1, the low pressure EGR device 1 having a structure for returning the EGR gas to the low intake negative pressure generation range is configured to supply a large amount of EGR gas to the engine. It is difficult to return.
In view of this, the low pressure EGR device 1 is provided with an intake throttle valve 7 for positively generating intake negative pressure in the intake passage 4 for returning EGR gas, and in the operation region where the low pressure EGR device 1 wants to obtain a large EGR amount, The opening degree is controlled in the direction in which the intake throttle valve 7 is closed (the direction in which intake negative pressure is generated), so that a large amount of EGR gas can be controlled in the low pressure EGR device 1.

But,
When the low-pressure EGR device 1 is used to return a small amount of EGR gas to the engine in a “low concentration control state”, the intake throttle valve 7 is fixed at the maximum opening (full opening) so as not to generate negative pressure. It is necessary to control the opening degree of only the low pressure EGR regulating valve 6,
In the “high concentration control state” in which a large amount of EGR gas is returned to the engine using the low pressure EGR device 1, the opening of the low pressure EGR adjustment valve 6 is increased and the intake throttle valve 7 is set to increase the negative pressure. It is necessary to reduce the opening.

Thus, in the “low concentration control state”, the intake throttle valve 7 is fixed fully open and only the low pressure EGR adjustment valve 6 is controlled in opening degree, and in the “high concentration control state”, the opening degree of the low pressure EGR adjustment valve 6 is supported. Thus, the opening degree of the intake throttle valve 7 also changes.
For this reason, a dedicated actuator for driving the low pressure EGR adjustment valve 6 and a dedicated actuator for driving the intake throttle valve 7 are required. It becomes the factor of up and weight up.

  Therefore, as shown in FIG. 8, the low pressure EGR device 1 includes one electric actuator 8 that drives the low pressure EGR adjustment valve 6, and a link device that drives the intake throttle valve 7 by changing the output characteristics of the electric actuator 8. 9, and the intake throttle valve 7 is driven by the output of the electric actuator 8 transmitted via the link device 9.

The link device 9 is provided with a characteristic conversion unit that changes the output characteristic of the electric actuator 8 and transmits the change to the intake throttle valve 7, and after the low pressure EGR adjustment valve 6 becomes larger than a predetermined opening, the low pressure EGR adjustment valve. 6 is provided so as to reduce the opening of the intake throttle valve 7 (see FIG. 6).
6 indicates the change in the EGR flow rate with respect to the rotation angle of the low pressure EGR adjustment valve 6, and the solid line 7 ′ in FIG. 6 indicates the change in the intake flow rate by the intake throttle valve 7 with respect to the rotation angle of the low pressure EGR adjustment valve 6. Is shown.

[Description of Low Pressure EGR Valve Unit 2]
The low pressure EGR adjustment valve 6 and the intake throttle valve 7 are driven by a drive device including an electric actuator 8 and a link device 9, and this drive device, together with the low pressure EGR adjustment valve 6 and the intake throttle valve 7, is a low pressure EGR. Mounted on the valve unit 2.

The low pressure EGR valve unit 2 includes a valve housing 41 having a joining portion of the low pressure EGR flow path 5 and the intake passage 4, the low pressure EGR adjustment valve 6, the intake throttle valve 7, and the driving device (electric actuator 8 + link device 9). Is mounted.
Hereinafter, the low pressure EGR adjustment valve 6, the intake throttle valve 7, the electric actuator 8 constituting the drive device and the link device 9 mounted on the low pressure EGR valve unit 2 will be described in order.

The low pressure EGR adjustment valve 6 is a butterfly valve disposed in the low pressure EGR flow path 5, and rotates integrally with a low pressure EGR shaft 42 that is rotatably supported with respect to the valve housing 41.
The intake throttle valve 7 is a butterfly valve disposed in the intake passage 4, and rotates integrally with an intake throttle shaft 43 that is rotatably supported with respect to the valve housing 41.
The low pressure EGR shaft 42 and the intake throttle shaft 43 are arranged in parallel.

Here, the low-pressure EGR valve unit 2 is urged in a stopper member (not shown) that stops the intake throttle valve 7 at the maximum opening and a direction in which the intake throttle valve 7 is brought into contact with the stopper member (fully opened direction). A return spring (not shown) is provided.
As a result, in the state where the drive load is not applied to the intake throttle valve 7 from the electric actuator 8 via the link device 9, the intake throttle valve 7 is returned to the maximum opening degree by the urging force of the return spring.
The stopper member may be in contact with the driven arm 14 or in contact with the intake throttle valve 7 in the intake passage 4.

The electric actuator 8 is
An electric motor 8a (for example, a DC motor) that generates rotational output when energized;
A gear reduction device 8b that decelerates the rotational output of the electric motor 8a and increases the output torque;
And is arranged in a drive unit accommodation chamber 41a provided outside the intake passage 4 and the low pressure EGR flow path 5.

The gear reduction device 8b includes a pinion 44 fixed to the output shaft of the electric motor 8a, an intermediate gear 45 rotatably supported between the electric motor 8a and the intake throttle shaft 43, and a final coupled to the intake throttle shaft 43. And a gear 3.
The intermediate gear 45 is integrally provided with a large-diameter gear 45a that meshes with the pinion 44 of the electric motor 8a and a small-diameter gear 45b that meshes with the final gear 3.
The low-pressure EGR adjustment valve 6 is driven by the output of the gear reduction device 8b (the rotation of the final gear 3), and the intake throttle valve 7 is driven via the link device 9.

  Similar to the electric actuator 8, the link device 9 is disposed in the drive unit accommodating chamber 41a, converts the output characteristic (rotation characteristic) of the electric actuator 8, and drives the intake throttle valve 7. The low pressure EGR A cam plate 12 that rotates integrally with the adjustment valve 6 and a driven arm 14 that rotates integrally with the intake throttle valve 7 are provided.

The cam plate 12 has a plate shape and is fixedly disposed at a right angle to the low pressure EGR shaft 42.
The driven arm 14 also has a plate shape, and is coupled to the intake throttle shaft 43 at a right angle so that the rotating end side of the driven arm 14 overlaps the cam plate 12 with a predetermined gap. Is.

In the link device 9, the characteristic conversion unit that converts the output characteristic of the electric actuator 8 is provided at a position away from the rotation center of the cam groove 11 provided at the position away from the rotation center of the cam plate 12 and the rotation center of the driven arm 14. And a cam groove engaging portion 13 that fits into the cam groove 11.
The cam groove engaging portion 13 is a cylindrical roller (rotational difference absorber) that fits in the cam groove 11, and is rotatably supported by a shaft portion provided on the rotating end side of the driven arm 14. .

The cam profile of the cam groove 11 is provided by connecting the “opening keep cam groove 11a” and the “intake throttle cam groove 11b”.
The “opening keep cam groove 11 a” is “an arc groove having the same center as the rotation center of the cam plate 12”, and the fully closed opening θ 0 (FIG. 5) at which the low pressure EGR adjustment valve 6 restricts the low pressure EGR flow path 5 to the maximum. 6 is provided to keep the opening of the intake throttle valve 7 at the maximum opening in the rotation range (opening θ0 to opening θ1) from the EGR valve opening of 0 = 0 to the predetermined intermediate opening θ1. Yes.

  The “intake restricting cam groove 11 b” is formed so as to continue to one end of the “opening keep cam groove 11 a” described above, and “an arc having the same center as the rotation center of the cam plate 12. “Lower angle EGR regulating valve 6 changes from a predetermined intermediate opening (θ1) to a maximum opening (θ2: EGR valve opening = 90 ° in FIG. 6). The driven arm 14 is rotated in a rotation range (opening angle θ1 to opening angle θ2), and the opening degree of the intake throttle valve 7 is set to rotate from the maximum opening degree to the direction of closing the intake passage 4. Yes.

[Feature technology 1 in the embodiment]
The final gear 3 of the gear reduction device 8b rotates integrally with the cam plate 12.
Therefore, as shown in FIG. 8, it is conceivable to provide the final gear 3 and the cam plate 12 integrally.
Since the cam plate 12 is required to have wear resistance and load resistance, the cam plate 12 is required to be provided with a hard metal such as iron. For this reason, when the final gear 3 and the cam plate 12 are made of an integral metal, strength and reliability can be obtained, but there is a problem that cost and weight increase.

In contrast, in this embodiment, as shown in FIG.
-The cam plate 12 that requires high strength is made of metal (for example, stainless steel or iron metal),
-The final gear 3 that does not require such high strength is provided with resin (for example, nylon resin),
By attaching and fixing a metal cam plate 12 to the final gear 3 made of resin, cost reduction and weight reduction are achieved.

  As a means for attaching the metal cam plate 12 to the final resin gear 3, in this embodiment, as shown in FIGS. 1 and 9, a metal nut part β is inserted into the final gear 3 in advance. A means for fixing the metal cam plate 12 to the resin final gear 3 by attaching the cam plate 12 to the final gear 3 and fastening the screw γ to the nut part β is adopted.

That is, the final gear 3 is an example of a resin gear part with a nut to which the present invention is applied.
A resin gear part α in which the gear teeth 3a are provided only within a predetermined rotation range (a rotation range wider by a small margin than the rotation range of the intake throttle valve 7);
A plurality of (three in this embodiment) metal nut parts β inserted into the resin of this resin gear part α;
It is configured with.

  As shown in FIG. 1B, the resin gear part α in this embodiment includes, in addition to the nut part β, a metal plate 46 fitted to the low pressure EGR shaft 42 and the opening of the low pressure EGR regulating valve 6. The magnetic flux generator 47 (magnet + iron yoke) of the rotation angle sensor that detects the degree of contact in a non-contact manner by magnetism is inserted, but of course is not limited.

Here, in this embodiment, as shown in FIG.
-One rotation end of the gear tooth 3a is connected to one gear end A,
The other rotation end of the gear tooth 3a is connected to the other gear end B,
The rotation center of the resin gear part α is the rotation center C,
-The center of the female thread in the nut part β is the nut center D,
-A straight line connecting one gear end A and the rotation center C is a virtual straight line AC,
A straight line connecting the other gear end B and the rotation center C is represented by a virtual straight line B-C,
The range of the resin gear part α on the side divided by the virtual straight line AC and the virtual straight line BC and provided with the gear teeth 3a is the geared range θa,
The range of the resin gear part α on the side partitioned by the virtual straight line AC and the virtual straight line BC and not provided with the gear teeth 3a is the gear no range θb,
It is defined as

In the resin gear part α, the nut center D is not arranged in the geared range θa, but the nut center D is arranged only in the gearless range θb.
The nut center D may be arranged on at least one of the virtual straight line A-C or the virtual straight line B-C.

By adopting this feature technology 1, when the resin gear part α is injection-molded in the mold (during resin molding), the flow of molten resin {see arrow X in FIG. 1B} wraps around the nut part β. As a result, the weld formed in the resin gear part α is formed only in a portion where the gear teeth 3a do not exist.
That is, it is possible to prevent the weld from being formed on the gear teeth 3a during resin molding, and it is possible to prevent the strength of the gear teeth 3a from being lowered due to the weld.

Further, by adopting the feature technique 1, the spread of the flow of the molten resin toward the gear teeth 3a (see the broken line Y in FIG. 2B) is not hindered by the nut part β during resin molding.
For this reason, poor filling of the molten resin into the gear teeth 3a is suppressed, and a reduction in dimensional accuracy of the gear teeth 3a can be prevented.

  In this way, by adopting the feature technique 1, it is possible to prevent the strength and accuracy of the gear teeth 3a from being lowered and to improve the reliability of the final gear 3 made of resin. As a result, the reliability of the low-pressure EGR device 1 Can be increased.

[Feature technology 2 in the embodiment]
The feature technique 2 will be described with reference to FIG.
As shown in FIG. 3A, it is conceivable to provide only one gate δ into which the resin is poured into the mold during the injection molding of the final gear 3 within the geared range θa.
However, when the number of gates δ in the geared range θa is only one, the spread of the molten resin flow toward the gear teeth 3a {refer to the broken line Y in the figure) during resin molding is the formation range of the gear teeth 3a. On the other hand, it is not evenly guided. As a result, there is a concern about poor filling of the molten resin into the gear teeth 3a, which may cause a reduction in dimensional accuracy of the gear teeth 3a.

In order to solve this problem, in this embodiment, the number of gates δ into which resin is poured into the mold during the injection molding of the final gear 3 is within the geared range θa as shown in FIG. Two or more are provided.
Specifically, in this embodiment, there are two gates δ provided in the geared range θa.

Here, in this embodiment, as shown in FIG.
The distance between the gate δ in the geared range θa and the gate δ in the geared range θa adjacent to the gate δ (the distance between adjacent gates in the geared range θa) is expressed as the inter-gate distance L,
-A distance 1/2 of the distance L between the gates is defined as a merging distance L1,
The distance from the gate δ within the gear range θa to the gear bottom of the gear tooth 3a is defined as the gear tooth reach distance L2,
It is defined as

The feature technique 2 is provided so as to satisfy the relationship of “the confluence distance L1 <the gear tooth reach distance L2”.
As a result, the molten resin flowing out from the gate δ in the geared range θa merges with the molten resin flowing out from the gate δ in the other geared range θa before reaching the gear bottom of the gear tooth 3a. As a result, as shown in FIG. 3C, the spread of the joined molten resin flow (see broken line Y in the figure) spreads from the inner diameter direction to the outer diameter direction. For this reason, resin can be uniformly filled with respect to the gear teeth 3a, and a reduction in dimensional accuracy of the gear teeth 3a can be prevented.

  Further, even if a plurality of gates δ are provided in the geared range θa, by adopting the feature technique 2, the resin is filled in the gear teeth 3a after the molten resin has merged. The trouble that the weld is formed on the gear tooth 3a does not occur by the provided gate δ, and it is possible to prevent the strength of the gear tooth 3a from being lowered by the weld.

[Feature technology 3 in the embodiment]
The feature technique 3 will be described with reference to FIG.
It is conceivable that the number of gates δ in the gearless range θb is equal to or greater than the number of gates δ in the geared range θa.
As a specific example, as shown in FIG. 4A, it is conceivable to provide two gates δ in the geared range θa and two gates δ in the gearless range θb.

  However, in the case where “the number of gates in the geared range θa ≦ the number of gates in the gearless range θb” is provided, as shown in FIG. The molten resin spreading from (see the broken line Y1 in the figure) and the molten resin spreading from within the gearless range θb (see the broken line Y2 in the figure) merge at the geared range θa, forming a weld on the gear tooth 3a. There is a concern to be.

In order to solve this problem, in this embodiment, the number of gates in the geared range θa is larger than the number of gates in the gearless range θb. In other words, the relationship is “the number of gates in the geared range θa> the number of gates in the gearless range θb”.
Specifically, the number of gates in this embodiment is such that two gates δ are provided in the geared range θa and one gate δ is provided in the gearless range θb, as shown in FIG. It is.

Thus, during resin molding, resin filling in the geared range θa is fast, and conversely, resin filling in the gearless range θb is slowed. For this reason, the joining point of “the molten resin spreading from within the geared range θa (see broken line Y1 in the figure)” and “the molten resin spreading from within the gearless range θb (see broken line Y2 in the figure)” It can be within θb.
As a result, the weld due to the joining point between the “molten resin spreading from within the geared range θa (see the broken line Y1 in the figure)” and “molten resin spreading from within the gearless range θb (see the broken line Y2 in the figure)” is the gear. The trouble formed in the teeth 3a can be avoided, and the strength reduction of the gear teeth 3a due to the weld can be avoided.

  In the above-described embodiment, an example in which the present invention is applied to the final gear 3 in the driving device of the low pressure EGR valve unit 2 has been described. However, the driving device using the electric actuator 8 (electric motor 8a + gear reduction device 8b) and the cam plate 12 is used. For example, the present invention may be used for a variable capacity turbocharger drive device, a vehicle air conditioner door drive device, or the like.

  In the above embodiment, the example in which the present invention is applied to the final gear 3 of the gear reduction device 8b has been described. However, the present invention is not limited to the final gear 3, and the gear teeth 3a are only within a predetermined rotation range. Can be applied to resin gear parts.

  In the above embodiment, the cam plate 12 is shown as an example of the metal part assembled to the nut part β inserted into the resin gear part α. However, the present invention is not limited, and other metal different from the cam plate 12 is used. Parts may be assembled.

3 Final gear (resin gear parts with nuts)
3a Gear teeth 4 Intake passage 5 Low pressure EGR passage 6 Low pressure EGR adjustment valve 7 Intake throttle valve 8 Electric actuator 8a Electric motor 8b Gear reduction device 9 Link device 11 Cam groove 12 Cam plate A One gear end B The other gear end C Rotation Center D Nut Center L Distance between Gates L1 Merge Distance L2 Gear Tooth Distance α Plastic Gear Parts β Nut Parts γ Screws δ Gate θa Geared Range θb Gear No Range

Claims (6)

A resin gear part (α) made of resin in which gear teeth (3a) are provided only within a predetermined rotation range;
One or more metal nut parts (β) inserted into the resin gear part (α);
In a resin gear part with a nut (3) comprising:
(A) One rotation end of the gear tooth (3a) is connected to one gear end A,
The other rotation end of the gear tooth (3a) is connected to the other gear end B,
The rotation center of the resin gear part (α) is the rotation center C,
The center of the female thread in the nut part (β) is defined as a nut center D,
(B) The range of the rotation direction of the resin gear part (α) is defined by an imaginary straight line AC connecting the one gear end A and the rotation center C, and the other gear end B and the rotation center C. Comparting with a virtual straight line BC
A section range on the side where the gear teeth (3a) are provided is a geared range θa,
When the division range on the side where the gear teeth (3a) are not provided is defined as the gear no range θb,
(C) A nut-equipped resin gear part, wherein the nut center D is disposed only in the gearless range θb. In the resin gear part (3) with a nut according to claim 1,
Two or more gates (δ) for pouring resin into the mold during injection molding of the resin gear part (α) are provided in the geared range θa,
The distance between the gate (δ) in the geared range θa and the gate (δ) in the geared range θa adjacent to the gate (δ) is expressed as an inter-gate distance L,
A distance half of the distance L between the gates is defined as a merging distance L1,
When the distance from the gate (δ) in the gear range θa to the gear bottom of the gear tooth (3a) is defined as the gear tooth reach distance L2,
Junction distance L1 <Gear tooth reach distance L2
Resin gear parts with nuts that satisfy the following relationship. In the resin gear part (3) with a nut according to claim 1 or 2,
The number of gates (δ) for pouring resin into the mold during injection molding of the resin gear part (α) is greater in the geared range θa than in the gearless range θb. Resin gear parts with nuts. In the resin gear part (3) with a nut according to any one of claims 1 to 3,
The nut part (β) is screwed into a screw (γ) for fixing a metal cam plate (12) having a cam groove (11) to the resin gear part (α). Resin gear parts. In the resin gear part (3) with a nut according to any one of claims 1 to 4,
This nut-equipped resin gear part (3) is the final gear (3) of the gear reduction device (8b) that reduces the rotational output of the electric motor (8a). In the resin gear part (3) with a nut according to any one of claims 1 to 5,
This resin gear part with nut (3)
A low pressure EGR adjustment valve (6) for adjusting the opening of the low pressure EGR flow path (5) for introducing EGR gas to the intake passage (4) through which intake air passes;
An intake throttle valve (7) for generating an intake negative pressure at a junction of the intake passage (4) and the low pressure EGR flow path (5);
A resin gear part with a nut, characterized in that it is used in a drive device for driving a nut.

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