JPH0430393Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a trochoidal oil pump.

[Prior art] Trochoid pumps are compact and have a simple structure, so they are inexpensive, and the sliding speed between the external and internal teeth is low, so friction and meshing noise are small, and they also prevent contamination of the transport fluid. -Since it has the feature of high reliability against disturbances such as temperature rise, it has been widely used as oil pumps for vehicles such as oil pumps for automatic transmissions.

However, when a trochoid pump is used as an oil pump, one of the oil chambers defined between the inner teeth of the outer rotor and the outer teeth of the inner rotor sucks oil through the suction port as the outer rotor and inner rotor rotate. After leaving the suction port and completing oil confinement, when communicating with the discharge port, the high pressure oil in the discharge port suddenly acts on the oil in the oil chamber, causing the oil to flow backwards. The indoor oil pressure rises rapidly.
At this time, the rate of increase of the oil pressure in the oil chamber with respect to the rotation angle of the inner rotor is estimated to be three to four times that of a normal involute-type gear internal oil pump. For this reason, there is a problem that a hammer phenomenon occurs in the oil chamber due to the water hammer effect and noise is generated.Also, if air is mixed in the oil, the air may be mixed in due to the sudden pressure rise of the oil. There was a problem with the sudden compression of noise.

For example, as shown in FIG. 5, an oil chamber 104 defined between an inner rotor 101 and an outer rotor 102 in a trochoidal oil pump 100 starts to communicate with a discharge port 103.
(high pressure side oil chamber) and another oil chamber 106 (low pressure side oil chamber) which is completely closed on the trailing side and on the leading side of the suction port 105. ) is provided in the housing 108, and the high-pressure side oil chamber 10 when the pressure is rising.
4 is released to the low pressure side oil chamber 106 on the trailing side to partially recirculate the oil,
A system has been proposed in which the pressure of oil in the oil chamber 104 is increased slowly and smoothly (see, for example, Japanese Utility Model Publication No. 48984/1984).

However, such an arc-shaped communication groove 107
As shown in the cross section of Fig. 6, in order to obtain an appropriate orifice effect, the orifice must be placed accurately at a predetermined position, usually with a depth of several mm.
Even a slight deviation in the shape will reduce the discharge pressure and deteriorate the performance of the pump, so it is necessary to perform extremely precise machining. Therefore, with the conventional shape or processing method of the communication groove, it is difficult to ensure sufficient precision or the cost becomes high, and therefore improvements are required.

[Purpose of the invention] The present invention was devised in view of the above-mentioned conventional problems, and aims to smooth the rise in oil pressure in the oil chamber and eliminate the water hammer effect that occurs due to a sudden rise in oil pressure. The purpose of the present invention is to provide a simple and low-cost oil pump that prevents the hammering phenomenon caused by the oil pump or sudden compression of mixed air and reduces the amount of noise generated.

[Structure of the invention] In order to achieve the above object, the invention provides an outer rotor formed of sintered metal and having internal teeth, and an inner rotor having external teeth that engage with the internal teeth to define an oil chamber. In the trochoidal oil pump, an internal tooth notch is provided at the tip of the internal tooth, an external tooth notch is provided at the tip of the external tooth, and the internal tooth notch is connected to the internal tooth notch. When an oil chamber is in a position where oil is completely trapped after passing through the suction port, and the oil chamber adjacent to the leading side of the oil chamber is in communication with the discharge port, the external tooth notch is located between both oil chambers. Provided is an oil pump characterized in that the notches of the internal teeth and the external teeth of the oil pump overlap each other, and the overlapping portion gradually increases as the inner rotor and the outer rotor rotate.

[Effect of the invention] In the trochoid pump, the number of internal teeth of the outer rotor is one more than the number of external teeth of the inner rotor, so the rotation of the outer rotor lags behind one rotation of the inner rotor by one tooth. As a result, as the pump rotates, the notch provided at the tip of the external tooth of the inner rotor (internal tooth notch) becomes the notch provided at the tip of the internal tooth of the outer rotor (internal tooth notch). Department)
The position of the player shifts toward the leading side. Therefore, after one oil chamber separates from the leading end of the suction port and completes oil containment, the external tooth notch and the internal tooth notch located at the leading end of this oil chamber They begin to overlap, and the amount of overlap increases as the pump rotates. On the other hand, the oil chamber (low-pressure side oil chamber) communicates with the oil chamber (high-pressure side oil chamber) adjacent to the leading side through the overlapped portion, so the high-pressure side oil chamber communicates with the low-pressure side oil chamber and the discharge port. As the overlapping portion increases, the degree of communication gradually increases, and the pressure of the oil in the high-pressure side oil chamber is gradually transmitted to the oil in the low-pressure side oil chamber. Therefore, the pressure of the oil in the low-pressure side oil chamber increases slowly and smoothly, and the generation of noise due to sudden compression of air mixed in the oil is effectively prevented. Further, since the pressure of the oil in the low-pressure side oil chamber is gradually increased after the oil is trapped, no water hammer effect occurs when the oil communicates with the discharge port, and noise caused by the hammer is effectively prevented.

[Example] Hereinafter, embodiments of the present invention will be described in detail.

As shown in FIG. 1, in a cylindrical space 3 formed in the center of the housing 2 of the trochoidal oil pump 1, there are ten external teeth 4 having a tooth profile formed by a trochoidal envelope. an inner rotor 6 rotatably driven by an eccentric shaft 5, and
In addition to being provided with 11 internal teeth 7 that engage with the external teeth 4 (the number of external teeth is always one more than the number of internal teeth in a trochoid pump), the outer peripheral portion is in sliding contact with the inner peripheral wall of the space 3. As the inner rotor 6 rotates,
An outer rotor 8 that is rotated in the same direction is provided. Then, each outer tooth 4 of the inner rotor 6
The tips of the teeth are always in sliding contact with one of the inner teeth 7 of the outer rotor 8, and thereby the outer teeth 4, the inner teeth 8, the side wall of the space 3 of the housing 2, and the pump cover (not shown) Ten oil chambers 11 are formed by the inner surface of the oil chambers 11, which do not communicate with each other (however, they communicate through cutouts as will be described in detail later). Each of these oil chambers 11 rotates around the eccentric shaft 5 as the inner rotor 6 rotates, and when it is in a position communicating with the suction port 12, its volume increases with the rotation and the oil chambers 11 are connected to each other through the suction port 12. The oil is sucked in from the oil suction passage 13, and its volume reaches its maximum when it passes through the leading end of the suction port 12.At this time, when it is in a position communicating with the discharge port 14, its volume decreases as it rotates. A series of strokes in which oil is discharged into the oil discharge passage 15 through the discharge port 14 are continuously repeated, and the oil is supplied to a predetermined device at a predetermined discharge pressure (for example, 20 kg/cm ² ). This is the basic configuration. Note that the oil is supplied from the oil tank (not shown) to the suction port 16.
The oil is introduced into the oil pump 1 through a discharge port 17, and is supplied from the oil pump 1 to a predetermined device through a discharge port 17.

As shown in FIG. 2, external tooth notches 21 are provided on both sides of the tip of each external tooth 4 of the inner rotor 6 (FIG. 2 shows only two external teeth 4, Other external teeth 4 are not shown.) These external tooth notches 21 are thinly cut inward in the thickness direction from the side surface of the inner rotor 6, as shown in cross section in FIG. In this embodiment, the external tooth notches 21 are provided on both sides of the inner rotor 6, but they may be provided only on one side, or at an intermediate position in the thickness direction, as shown by P in FIG.

As shown in FIG. 2 again, internal tooth notches 22 are provided on both sides of the tip of each internal tooth 7 of the outer rotor 8 (only two internal teeth 7 are shown). ). These internal tooth notches 22 are
It has substantially the same dimensions as the external tooth notch 21 so as to properly engage with the external tooth notch 21.

Hereinafter, one oil chamber 11a, an external tooth notch 21a provided at the tooth tip of the external tooth 4a located at the leading end thereof, and an internal tooth notch provided at the tooth tip of the internal tooth notch 7a. The function of both notches will be explained using the section 22a as an example.

As shown in FIG. 2, the oil chamber 11a rotates while sucking oil from the suction port 12, and when the volume reaches the maximum, it separates from the suction port and completes the oil containment, when the external tooth notch The leading side end of the internal tooth notch 22a contacts the trailing side end of the internal tooth notch 22a (this point in time is referred to as the point in time when engagement of the notch starts). Since the number of teeth on the outer rotor 8 is one more than the number of teeth on the inner rotor 6, the rotation of the outer rotor 8 lags behind the inner rotor 6 by one tooth per rotation, and the outer teeth 4a are more than the inner teeth 7a in the oil chamber 11.
As a rotates, it advances toward the leading side.
Therefore, after the notch engagement starts, an overlapping portion is created between the external tooth notch 21a and the internal tooth notch 22a, and this overlapping portion increases as the oil chamber 11a rotates.

For example, when the oil chamber 11a rotates to the state shown in FIG. 4, an overlapping portion as shown in FIG. 4 occurs. At this time, the oil chamber 11a communicates with the oil chamber 11b adjacent to the leading side of the oil chamber 11a through the overlapping portion.

On the other hand, at the time when the engagement of the notch starts, the oil chamber 11
The oil chamber 11b adjacent to the leading side of a is in communication with the discharge port 14 and is therefore already under high pressure. After the notch engagement starts, the oil chamber 11a is connected to the high pressure side oil chamber 11b and the external gear notch 21a.
The pressure of the oil in the low-pressure side oil chamber 11a begins to rise because the oil in the low-pressure side oil chamber 11a communicates through the overlapped portion of the inner tooth notch 22a. The overlapping portion gradually increases as the oil chamber 11a rotates, so the high pressure side oil chamber 11
The pressure transmitted from b to the low-pressure side oil chamber 11a, or the oil flowing in, gradually increases as the oil chamber 11a rotates after the notch engagement starts.
For this reason, the low pressure side oil chamber 11a and the high pressure side oil chamber 11b
At the start of communication, there is no sudden pressure change in the low-pressure side oil chamber 11a, and the pressure rises smoothly after that, so even if air is mixed in the oil, its sudden compression will not occur, and this will cause no sudden pressure change. The generation of noise caused by this is prevented. Further, the oil chamber 11a rotates further and its leading side end becomes the high-pressure discharge port 1.
4, the pressure of the oil in the oil chamber 11a is already high, so a sudden pressure increase does not occur in the oil chamber 11a due to communication with the discharge port 14, and hammering occurs due to the water hammer effect. This prevents noise caused by the hammer.

[Brief explanation of the drawing]

FIG. 1 is a front view of a trochoidal oil pump showing an embodiment of the present invention. FIG. 2 is an enlarged front view of the outer rotor and inner rotor of the trochoidal oil pump shown in FIG. 1. Third
The figure shows A- of the tooth tip of the inner rotor shown in Fig. 2.
FIG. FIG. 4 is an explanatory diagram showing an overlapping portion between an external tooth notch and an internal tooth notch. FIG. 5 shows a conventional trochoidal oil pump in which a communication groove is provided in the housing to smooth the rate of pressure rise in the oil chamber. FIG. 6 is an explanatory cross-sectional view taken along line B-B of the housing of the conventional trochoidal oil pump shown in FIG. 1...Oil pump, 2...Housing, 4...
...External teeth, 6...Inner rotor, 7...Internal teeth, 8...
... Outer rotor, 11 ... Oil chamber, 12 ... Suction port, 14 ... Discharge port, 21 ... External tooth notch, 22 ... Internal tooth notch.

Claims (1)

[Claims for Utility Model Registration] Trochoid type oil comprising an outer rotor made of sintered metal and having internal teeth, and an inner rotor having external teeth that engage with the internal teeth to define an oil chamber. In the pump, an internal tooth notch is provided at the tip of the internal tooth, and an external tooth notch is provided at the tip of the external tooth, and the internal tooth notch and the external tooth notch are connected to each other. When an oil chamber is in a position where oil has been completely trapped after passing through the suction port, and the oil chamber adjacent to the leading side of the oil chamber is in communication with the discharge port, each of the internal and external teeth between the two oil chambers An oil pump characterized in that the cutout portions overlap each other and the overlapping portion is arranged so as to gradually increase as the inner rotor and the outer rotor rotate.