JPS6183492A - Vane pump - Google Patents

Abstract

PURPOSE:To stabilize transfer torque, by a method wherein, when a vane is brought into contact with the inner peripheral surface of the small part of a cam ring, a vane push-up member, forced into contact with the under surface of the vane, is located on the one end surface on the inner rotor side, and the vane is forced into reliable slide contact with the ring. CONSTITUTION:A ring 53, being a push-up member, is mounted to the bottom of a vane containing groove 50 on one end surface side of an inner rotor 30, and the bottom surface of a vane 44 is adapted to make slide contact with the ring 53 when the forward end of the vane 44 makes slide contact with the inner peripheral surface of a cam ring 29 at the small part of the cam ring 29. This prevents the vane 44 from being moved further to the inner peripheral side of the inner rotor 30. Thus, even if a pressure difference between the forward end and the bottom part of the vane 44 is produced at the small part of the cam ring 29, since the vane 44 makes contact with the ring 53 and is prevented from being further moved to the inner side of the containing groove 50, the forward end of the vane 44 is always brought into slide contact with the inner peripheral surface, and eliminates a fear of an oil pressure being escaped due to formation of a gap. This enables stable provision of desired torque, and improves reliability of a pump.

Description

[Detailed Description of the Invention] Field of Use in Automotive Industry> The present invention relates to an improvement of a vane pump that generates fluid pressure by a difference in rotational speed, and is particularly applicable to the power of a four-wheel drive vehicle in which the front and rear wheels are driven by the same engine. It is suitable for use in communication.

<Prior art> In a four-wheel drive vehicle where the front and rear wheels are driven by the same engine, if there is a slight difference in the effective radius of the front and rear tires, the tires may slip, causing damage to the drive system. Unreasonable force acts. This problem also occurs when turning, where the front and rear wheels have different transfer trajectories, so some kind of countermeasure must be taken.For this reason, in full-time four-wheel drive vehicles that cannot shift to two-wheel drive, A third differential device called a center differential is used to transmit driving force even if a rotational difference occurs between the rotating shaft that transmits driving force to the front wheels and the rotating shaft that transmits driving force to the rear wheels. However, it is disadvantageous compared to part-time four-wheel drive vehicles capable of two-wheel drive in terms of M quantity, size, and cost. Moreover, since differential rotation is possible, the four-wheel drive F4H? There are cases where four-wheel drive cannot be achieved when required, and a differential lock mechanism must be incorporated for this purpose, which has the drawback of complicating the entire device.

On the other hand, in the above-mentioned part-time four-wheel drive vehicles, when a problem occurs due to four-wheel drive such as tight corner braking, the driver is required to switch to two-wheel drive, which makes driving operations complicated and common. It is difficult for users to master it.

Therefore, as shown in Figure 2, a part-time four-wheel drive vehicle is being considered, equipped with a power transmission device using a vane pump that automatically switches to two-wheel drive according to the rotational difference between the scraping and rear wheels. . This is connected to the engine 11 and 7'(
Driving force is taken out from the output shaft 13 of the transmission 12, is attached to the output 41113, and is transmitted from the mental drive gear 14 via the idle gear 15 to the intermediate transmission shaft 18 having gears 16.17t at both ends, and this intermediate Driving force is transmitted from the transmission shaft 18 to the front wheels 20 via a front wheel differential 19ft. On the other hand, the driving force transmitted to the front wheel 20 is directly transmitted to the front wheel rotating shaft 22 via the gear 21.
The power is transmitted to the rear wheel differential device 126 via the power transmission device 23 using the vane pump 23a(i) from the rear wheel rotating shaft 24 through the gear mechanism 25 for changing the direction of rotation. is driven.

As shown in FIG. 3, which shows the cross-sectional structure of the power transmission device 23, the vane pump 23a includes a cam IJ 7 ring 29, a nine-circular inner rotor 30 that is rotatably housed within the cam ring 29, and a nine-circular inner rotor 30 on the outer periphery of the inner rotor 30. The cam ring 29 is made up of a plurality of vanes 44 that are movably attached to a plurality of grooves formed in the radial direction, and whose tips slide against the inner circumferential surface of the cam ring 29, and the cam ring 29 has an oval oil chamber 28. A circular inner rotor 3 is integrally connected to a rotating shaft 24 and is rotatably housed within this oil chamber 28.
0 is integrally connected with a front wheel rotating shaft 22.

The cam ring 29 has four ports 31 , 3.2 , 33 . that communicate with the oil chamber 28 , respectively. ' 34 is formed, and the ports 31 are opposite to each other with the inner rotor 30 in between.
．． 33 are connected via a first oil passage 35tl-, and similarly ports 32.34 are connected via a second oil passage 36. An oil reservoir 39 communicates with the first oil passage 35 and the second oil passage 36 via check valves 37 and 38t, respectively.
- a pair of check valves 41 that can communicate with the oil sump 39 through the
42. A spring 43 that sets the opening pressure of the relief valve 40 is incorporated in the IJ IJ-fu valve 40, and opens when the pressure inside the first oil passage 35 or the second oil passage 36 exceeds a certain level to release pressure oil. is returned to the oil sump 39 side. In other words, if there is no relative rotation between the cam ring 29 and the inner rotor 30, the cam ring 29 will simply rotate freely, resulting in a two-wheeled state. However, when relative rotation occurs between them, hydraulic pressure is generated, and the relief valve 40 Since the flow of oil is blocked, the cam ring 29 and the inner rotor 30 rotate together due to the static pressure of this pressure oil, resulting in a four-wheel drive state.

For example, in a normal straight-ahead state, the effective radius of the front wheel 20 and rear wheel 27 tires are the same and their slip rotational speed is small, so that There is no difference in rotational speed. Therefore, no oil pressure is generated by the vane pump 2ja, and the rear wheel 2
No driving force is transmitted to the wheels 7, resulting in two-wheel drive using only the front wheels 20.

However, when the front wheels 20 normally slip at a rate of about 1% or less during acceleration even when driving straight, if a rotational speed difference due to this occurs in the curve between the front wheel rotation shaft 22 and the rear wheel rotation shaft 24, this Hydraulic pressure is generated according to the rotation difference, and the inner rotor 3
0 and the cam ring 29 rotate together, and a Kfh force corresponding to this oil pressure and the pressure receiving surface of the vane 44 is applied to the rear wheel 2.
7 and enters four-wheel drive mode. In this case, the inner rotor 30 rotates relatively, and the boat 32
．． 34 serves as a suction port, and an oil sump 39 is supplied via a reverse valve 38.
While oil is sucked in from the valve 31.33 as a discharge port, it is guided to the relief valve 40 via the check valve 41 at the same time as the check valve 37.42i closes.

Next, when the rotational speed of the front wheels 20 becomes much larger than the rotational speed of the rear wheels 27, for example, when the front wheels 20 slip on a snowy road, when accelerating suddenly, or when braking, the rear wheels 27 tend to lock up. In this case, the difference in rotation between the front wheel rotating shaft 22 and the rear wheel rotating shaft 24 of the power transmission device 23 becomes very large, generating a large oil pressure. If this oil pressure exceeds a predetermined value, the relief The valve 40 opens against the spring 43, the discharge pressure is controlled to be substantially constant, and a four-wheel drive state is established in which a constant driving force corresponding to the constant discharge pressure is transmitted to the rear wheels 27. As a result, the rotational speed of the front wheels 20 decreases and the rotational speed of the rear wheels 27 increases by QIJ, which acts to completely reduce the rotational difference (non-slip differential function) and when the front wheels 20 are in a slip state. It is possible to avoid an increase in the driving torque to the rear wheels 27, which makes it impossible to drive.
When the rear wheels 27 are a little locked, the brake torque of the front wheels 20 is increased to prevent the rear wheels 27 from locking.

On the other hand, when the rotational speed of the rear wheels 27 becomes very large compared to the rotational speed of the front wheels 20, for example, when the front wheels 20 are slightly locked in the braking state, the front wheel rotation shaft 22 of the power transmission device 23 and the rear wheel A very large rotational difference occurs between the rotary shaft 24 in the opposite direction to that described above, and the
serves as a suction port, and oil is sucked in from the oil sump 39 via the reverse valve 37, while the boat 32.34 serves as a discharge port.
The check valve 38° 41 is closed via the second oil passage 36t, and a large oil pressure is guided from the check valve 42 to the relief valve 40 and acts there, but this oil pressure is also kept constant by the relief valve 40. A constant driving force is transmitted to the rear wheels 27, resulting in a four-wheel drive state. As a result, the brake torque to the rear wheels 27 is increased to prevent the front wheels 20 from locking.

- During normal cornering, the rotational speed of the front wheels 20 is slightly higher than the rotational speed of the rear wheels 27, and a four-wheel drive state in which brake torque is applied to the front wheels 20 and retraction torque is applied to the rear wheels 27. As a result, turning movement is performed.

In order to operate the vane pump 23a'i accurately and to ensure full reliability, the tips of the vanes 44 radially attached to the inner rotor 30 must always come into contact with the inner peripheral surface of the cam ring 29 and enter the oil chamber 28. The first consideration is to be able to generate a desired static pressure.

<Problems to be solved by the invention> However, especially in the short diameter portion of the cam ring 29, r
The pressure inside the outlet chamber 28 becomes high, and the bottom of the vane 44 temporarily becomes a low pressure state, causing the bezel 744 to move inward, causing the vane 4 that should be in contact with the circumferential surface of the cam ring 29 to
4 may not come into contact with each other reliably, causing oil to flow directly from the discharge port to the suction port through this gap, resulting in a drop in oil pressure and torque fluctuations, resulting in the inability to generate the desired transmitted torque. . This is due to centrifugal force vane 4
This is noticeable in the low rotation range of the inner rotor 30 where the push-up blade of No. 4 cannot be sufficiently obtained. To solve this problem,
It is conceivable to use a spring or the like to push up the page 744 in the radial direction of the inner rotor 30 using a force that resists the oil pressure difference, but in order to resist the oil pressure difference, it is necessary to use a fairly strong spring made of paneka, which poses a problem in terms of space. This is difficult to achieve.

The present invention was developed in view of the above situation, and even if the vane is attached to the inner rotor and the vane is located at the short diameter part of the cam ring where a pressure difference is likely to occur between the tip and bottom of the vane, the tip of the vane is always kept in contact with the cam ring. The purpose of this book is to provide a vane pump that can be pressed against the inner circumferential surface, thereby improving the reliability of the vane pump. The structure of the invention is such that an inner rotor is relatively rotatably housed in a cam ring whose inner circumferential surface has a cam shape, and a vane that is movable in the radial direction of the inner rotor and whose tip is in sliding contact with the inner circumferential surface of the cam ring is provided. In the vane pump, a large number of vanes are attached to the outer periphery of an inner rotor, and the volume of a space surrounded by the inner rotor, the cam ring, and the vane is changed by relative rotation of the inner rotor and the cam ring, thereby generating fluid pressure therein. A vane pushing member that comes into contact with the bottom surface of the vane when the vane is in contact with the inner circumferential surface of the short diameter portion of the cam ring is provided on at least one end surface of the inner rotor or the cam ring. , the vane is prevented from moving inward more than necessary in the short diameter portion of the cam ring, and the vane is securely brought into sliding contact with the inner circumferential surface of the cam ring.

<Example> FIG. 1 is a complete representation of a vane pump according to an example of the present invention,
FIG. 1(a) shows a cross-sectional side view, and FIG. 1(b) shows a front view with the cover removed. This embodiment is applied to the power transmission device of the drive mechanism of a four-wheel drive vehicle shown in Figs. 2 and 3, and the same members are denoted by the same reference numerals. A detailed explanation will be omitted.

A bolt 45 is attached to one side of the cam ring 29, which has an input gear 29a formed on the outer periphery with which the gear of the front wheel rotating shaft 24 meshes.
The cover 7 flange 46 is attached to the other side, and the output 7 lange 48 is attached to the other side via a bushing retainer 47f with bolts 45. This cover 7
The rear wheel rotating shaft 22 is integrally connected to the oil chamber 28 formed in the cam ring 29 by the second hinge 46 and the bushing retainer 47 via the bushing 49 and a spline 30a'i formed in the inner rotor 30. A connected nine-circular inner rotor 30 is rotatably housed in the inner rotor 30, and a vane storage groove 5° for holding a plate-shaped vane 44 slidably in the radial direction is formed in a radial manner. ing. Additionally, four boats 31, 32, 33.
An oil passage 51 communicating with the bush retainer 47 is provided.
An oil passage 52 is formed in the inner rotor 30 and communicates with the recess 30b to supply hydraulic pressure for pushing up the vane.
is provided. A ring 53, which is a vane pushing member, is attached to the bottom of the vane storage groove 5o on one end surface side of the inner rotor 3o, and the cam ring 2
When the tip of the vane 744 is in sliding contact with the inner peripheral surface of the cam ring 29 at the short diameter portion of the vane 9, the bottom surface of the vane 44 comes into contact. In other words, the bottom surface of the vane 44 at the short diameter portion of the cam ring 29 is in contact with the ring 53 with the tip thereof in sliding contact with the inner circumferential surface of the cam ring 29, and the vane 44 can no longer move toward the inner circumferential side of the inner rotor 30. I don't.

Therefore, even if a pressure difference occurs between the tip of the vane 44 and the bottom of the vane 44 at the short diameter portion of the cam ring 29, the vane 44
Since the vane 44 contacts the ring 53 and does not move further inside the storage groove 5o, the tip of the vane 44 always touches the cam ring 2.
9. Sliding contact with the inner circumferential surface eliminates the risk of hydraulic pressure leaking due to gaps.

The application is not limited to the above embodiments, but can be widely used as a fluid pressure pump for various machines.

Furthermore, although the ring 53 is provided on the inner rotor 30 in this embodiment, it may be provided on a cover or the like that is integrated with the cam ring 29.

<Effects of the Invention> According to the present invention, even in the short diameter portion of the cam ring where a pressure difference is likely to occur between the vane tip and the bottom, the vane tip is always in contact with the cam ring circumferential surface. No gap is created on the inner peripheral surface, and oil does not flow directly from the discharge boat to the suction port through this gap. As a result, the oil pressure decreases and the torque effect does not occur, and the transmitted torque can be stably obtained, making it possible to improve the illumination of the vane pump.

[Brief explanation of the drawing]

FIG. 1 shows a vane bomb according to an embodiment of the present invention,
Figure 1(a) is a cross-sectional side view, Figure 1(b) is a front view with the cover removed, and Figure 2 shows the drive mechanism of the part-time four-wheel drive vehicle that is the subject of the present invention. FIG. 3 is a sectional view showing the structure of the power transmission device. In the drawing, 28 is an oil chamber, 29 is a cam ring, 30 is an inner rotor, 44 is a vane, 50 is a vane storage groove, and 53 is a ring exit. Patent applicant Mitsubishi Motors Corporation agent Patent attorney Shibu Mitsuishi (and 1 other person) Figure 1 (0)

Claims (1)

[Claims] An inner rotor is relatively rotatably housed in a cam ring whose inner circumferential surface has a cam shape, and a vane that is movable in the radial direction of the inner rotor and whose tip is in sliding contact with the inner circumferential surface of the cam ring is provided on the outer circumference of the inner rotor. In a vane pump in which a large number of vanes are installed and the relative rotation of the inner rotor and the cam ring changes the volume of a space surrounded by the inner rotor, the cam ring, and the vane to generate fluid pressure therein, the vane has a short diameter of the cam ring. 1. A vane pump characterized in that a vane pushing member is provided on at least one end surface of the inner rotor or the cam ring, the vane pushing member contacting the bottom surface of the vane when the vane is in contact with the inner circumferential surface of the vane.