JPS6252154B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] This invention relates to a gear pump or motor, particularly one that can be used in both forward and reverse rotation.

[Conventional technology and its problems]

When a gear pump or motor is under high pressure, leakage from the gear side clearance increases, resulting in poor volumetric efficiency and reduced performance. To prevent this, a side plate that is movable in the axial direction or a side plate that is integrated with the bearing bushing is provided on the side surface of the gear, and the discharge side or By mainly applying high pressure fluid pressure on the suction side, it is balanced with the pressing force from the side of the gear, suppressing an increase in leakage from the gap on the side of the gear, and preventing a decrease in volumetric efficiency.

Figure 1 is a side sectional view of a gear pump/motor incorporating the above-mentioned bearing bush and integral side plate.
A driving gear 2, which is integral with the drive shaft 1, is meshed with a driven gear 4, which is integral with the driven shaft 3, and is housed in a casing 5, and the drive shaft is connected by bearing bushes 6, 6', which are also integral with the side plates housed therein. 1. A driven shaft 3 is rotatably supported. As shown in FIG. 2, these bearing bushes 6 and 6' are configured as a bearing block in which bearing bushes for the drive shaft and driven shaft are integrated, and the side plate surfaces thereof face the front cover 7 and the rear cover 8, respectively. It is made to be.

This type of means forms pressure chambers for introducing pressure fluid into the respective gaps between the side plate and the covers, and counteracts the pressing force from the side surface of the gear with the pressing force generated from the pressurized fluid stored in the chambers. Various attempts have been made in the past.

For example, in the case shown in FIG. 2, a third
An 8-shaped groove with a cross-sectional shape shown in the figure and a radial branch groove with a similar cross-sectional shape are provided, and a seal made of oil-resistant rubber, for example, and having a U-shaped cross-section as shown in FIG. A member 13 is housed as shown. Now the A side is the low pressure side,
When the B side is set as the high pressure side, the fluid (hydraulic oil) on the high pressure side B enters the groove through the gap between the groove and the seal member 13 and pushes out the seal member 13 from inside (in FIG. 3, it pushes up). ), the sealing member 3 is attached to the front cover 7 and the rear cover 8.
Press firmly. Therefore, pressure chambers separated by seal members 13, that is, a high pressure chamber H, a medium pressure chamber M, and a low pressure chamber L, are formed in the gaps between the side plates 6, 6', the front cover 7, and the rear cover 8, respectively. , the bearing bushes 6 and 6' are moved by the pressing force generated from the pressure fluid stored therein, and the pressing force generated from the reaction of the pressing force from the surface of the sealing member 13 against the front cover 7 and rear cover 8. It will be pressed against the sides of the gears 2 and 4. However, in the side plate 6', symmetrically with the side plate 6, H is a bottom pressure chamber and L is a high pressure chamber, and the same applies in the following description.

However, the pressing force of the fluid from the side surfaces of the toothed portions of the gears 2 and 4 is different in the low pressure chamber L, medium pressure chamber M, and high pressure chamber H and is not uniform. In 13, since uniform high pressure in the high pressure chamber H acts on the entire circumference along the figure 8 shape, sealing members are installed in the low pressure chamber L and medium pressure chamber M portions by the front cover,
It is strongly pressed against the rear cover, and a pressing force is generated in the axial direction due to the reaction force. Therefore, the forces acting in the axial direction on the bearing bushes 6, 6' become unbalanced in the low pressure chamber L and medium pressure chamber M, and the unbalanced pressing force causes the sides of the gears 2, 4 to hit. They come into contact with each other, and at the same time perform a sealing action on the abutting surfaces, they also exert a braking action on these gears.

This is a drawback that occurs in a pump that has the side plates 6, 6' shown in FIG. 2 and has the high-pressure side B as the discharge side, or a gear motor that has the high-pressure side B as the suction side.
This problem also occurs in gear pump motors that are rotated in opposite directions, such that the A side is on the high pressure side and the B side is on the low pressure side.

The side plates 6, 6' shown in FIG. 4 are an example of the one shown in FIG. 2 with the above-mentioned drawbacks improved.
For example, the radial branch grooves, which have the same cross-sectional shape as the oil-resistant rubber groove, have seal members 14 made of the same material and have the cross-section shown in FIG. 5th against 2 grooves
As shown in the diagram, the 5th groove is for the upper and lower two grooves on the right side.
They are placed in the opposite direction from the illustration. The fluid (hydraulic oil) on the high pressure side B is pressed against the lips of the two upper and lower seal members 14 on the right side, and the seal member 1
It also invades the respective gaps (portion M shown blank) between the side plates 6, 6', front cover 7, and rear cover 8, which are separated by 3', 14. In addition, the high-pressure fluid enters the groove through the gap between the lip and the groove of the seal member 14 shown in the upper and lower two parts on the left side in FIG. By pressing with the lip, it acts to cut off the high pressure fluid. Therefore, the high pressure chambers formed in the gaps between the side plates 6, 6' and the front cover 7 and rear cover 8, respectively, are limited to the blank areas H and M. Then, the bearing bushes 6 and 6' are moved to the gears 2 and 2, respectively, by the pressing force generated from the pressure fluid stored in the high pressure chambers H, M and the low pressure chamber L, respectively.
It will be pressed against the side of 4.

On the other hand, as described above, the pressing force due to the fluid pressure from the side surfaces of the toothed portions of the gears 2 and 4 increases as it approaches from the low pressure side A to the high pressure side B, and is not uniform.
Therefore, in the bearing bushes 6, 6' integral with the side plates shown in FIG. 4, since the sealing member 13' is solid, the pressure on the high pressure side is applied to the sealing member as shown in FIG. Although it does not act on the surfaces of the front cover 7 and rear cover 8 along the entire circumference along 13', in the part M that becomes the high pressure chamber, the pressure of this part M and the side surface of the gear part opposite thereto Since this force acts as a contact force between the bearing bushes 6, 6', which are integral with the side plate, and the gears 2, 2', the seal can be sealed with less braking action than in the case shown in Fig. 2. I can make you do it. However, in the configuration in which the end surface of the seal member 14 is brought into contact with the circumferential surface of the seal member 13', the end surface of the seal member 14, which deforms each time the gear pump/motor is repeatedly stopped, strongly presses the circumferential surface of the seal member 13'. Therefore, due to the repetition of this process and the friction between both members, the seal members 13' and 14 are likely to be damaged, and from there, the high pressure fluid flows into the low pressure chamber L, and the pressing force from the side plates 6 and 6' is increased. becomes too large and exerts a braking effect on the gear in the same way as the side plate shown in FIG.

In view of the above-mentioned conventional drawbacks, this invention prevents fluid pressure on the high-pressure side from acting on the low-pressure chamber and the medium-pressure chamber, and provides a sealing member that separates the low-pressure chamber, medium-pressure chamber, and high-pressure chamber, respectively. An object of the present invention is to provide a gear pump motor that can maintain good operating performance over a long period of time by eliminating damage at the contact portion between the seal member that separates the atmospheric pressure region from the inside of the casing.

[Means for solving problems]

In order to achieve the above object, the present invention has the following configuration.

That is, a pair of gears are fitted into the holes connected to the suction and discharge ports of the hydraulic oil in the casing, and the gears are engaged with each other to rotate. A gear pump or motor having a side plate that performs a seal, a high pressure chamber and a low pressure chamber connected to the high pressure side and the low pressure side of the gear meshing portion, respectively, on the side opposite to the side of the side plate that contacts the side surface of the gear; A medium pressure chamber is provided between these two pressure chambers, and an "8"-shaped groove is provided in the side plate around the shaft hole, and a groove in the shape of an "8" is provided in the side plate at both ends in the longitudinal direction, respectively, symmetrically with respect to the longitudinal center line. so that each pair of "shi" shaped grooves are connected to a part of the eight-shaped groove on the back side of the "shi" shape, and each pair of "shi" shaped grooves are connected in the longitudinal direction of the side plate in each pair of "shi" shaped grooves. A predetermined region at each end is provided so as to surround each other, and an endless seal member is placed in the 8-shaped groove, and an end seal member is placed in each of the 8-shaped grooves to form an 8-shaped endless seal member. The gist of the invention is a gear pump or motor characterized in that it is formed by overlapping both seal members so that a part of the outer peripheral surface and the back side surface of each "C" shaped end seal member are in close contact with each other. .

[Effect]

In the gear pump or motor according to the present invention configured as described above, the endless seal member fits in the figure-8 groove provided on the side surface of the side plate opposite to the surface that abuts the side surface of the gear. Provides a seal between the atmospheric region and the pressure chamber within the casing. Furthermore, an end seal member is fitted into a groove formed at both longitudinal ends of the side plate symmetrically with respect to the longitudinal center line and continuous with the figure 8 groove. The pressure chambers are overlapped with each other in close contact with the periphery of the endless seal member to divide the pressure chamber into a high pressure chamber, a medium pressure chamber, and a low pressure chamber,
The low pressure chamber and medium pressure chamber are no longer affected by the fluid pressure on the high pressure side. Then, the endless seal member was arranged to be housed in the figure-8 groove, and the end seal member was housed in the bow-shaped groove formed at symmetrical positions on both ends of the figure-8 groove in the longitudinal direction and connected to the figure-8 groove. As a result, the end face of the end seal member is not brought into contact with the circumferential surface of the endless seal member, but the end face of the end seal member is overlapped with the end face of the end seal member. Even if the endless seal member is deformed in the circumferential direction, the force exerted on the circumferential surface of the endless seal member due to the deformation is dispersed by the overlapping surfaces. Therefore, even when the gear pump/motor starts and stops, the circumferential surface of the endless seal member is not subjected to local pressing force even when the pressure changes. This avoids the phenomenon of repeated pressing force.
No damage to the endless seal member occurs.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings.

FIG. 6 is a front view of the side plate integrated with the bearing bushing incorporated in this embodiment. In the figure, reference numeral 15 denotes a sealing member, which is made of an endless flexible plastic material such as polytetrafluoroethylene and having a rectangular cross-sectional shape as shown in FIG. 7, and is provided surrounding the bearing holes 11 and 12. A pressing member 16 is made of an oil-resistant rubber material and has a circular cross-sectional shape as shown in FIG. It serves a purpose.

The upper and lower parts of the side plates 6, 6' are provided with a slit-shaped groove symmetrically with the groove in which the seal member 15 is accommodated, and a seal member 17 having the same cross-sectional shape and the same material as the seal member 15 is provided in the groove. is stored partially overlapping with the sealing member 15, and a pressing member 18 having the same cross-sectional shape and the same material as the pressing member 16 is also stored.

Next, the operation of the gear pump or motor equipped with the side plates 6, 6' and integral bearing bushes 6, 6' constructed in this way will be explained.

Now side B is the high pressure side, that is, the discharge side when used as a gear pump, and the suction side when used as a gear motor, and the A side is the low pressure side, that is, the suction side when used as a gear pump, and the suction side when used as a gear motor. This is the discharge side. Fluid (hydraulic oil) on the high pressure side B enters the gap between the side plates 6, 6', the front cover 7, and the rear cover 8, which are separated by the seal member 15 and the two upper and lower right seal members 17, and enters the high pressure chamber. H is formed.

In this case, the pressing member 16 does not perform a sealing action, but only serves to press the sealing member 15 against the inner surface of the groove in which it is accommodated, so the high pressure chamber H also covers the portion of the pressing member 16. It has been enlarged. Medium-pressure fluid enters the gaps between the side plates 6, 6', front cover 7, and rear cover 8 from the upper and lower notches of the bearing bushes 6, 6', and forms a medium-pressure chamber similar to the high-pressure chamber H. A low pressure chamber L is formed on the low pressure side A in the same manner as described above. The bearing bushes 6 and 6' are pressed against the sides of the gears 2 and 4 by the pressing force generated from the pressure fluid stored in the three pressure chambers, respectively, so that on the surfaces in contact with the gears 2 and 4, A suitable sealing action can be achieved by countering the pressing force generated from the fluid pressure acting from the toothed portion. Further, in contrast to the above, a similar sealing effect can be achieved in a gear pump motor which is rotated in the opposite direction, with the A side set to the high pressure side and the B side set to the low pressure side.

Even in a gear pump motor equipped with the side plates 6 and 6', friction is generated between the seal members 15 and 17 due to the action of high-pressure fluid at the contact area between the seal members 15 and 17 each time the gear pump motor is repeatedly started and stopped. The seal member 17 is partially overlapped on the circumferential surface of the seal member 15, and the groove is formed by the seal member 17 to separate the high pressure chamber H, medium pressure chamber M, and low pressure chamber L from each other. Since the sealing member 17 is housed in the holder and overlaps the circumferential surface of the sealing member 15, unlike in the past, the end face of another sealing member is brought into contact with the circumferential surface of the sealing member and pressure is applied locally. In addition, these two members 15, 1
7 is made of a plastic material with a small coefficient of friction, such as polytetrafluoroethylene, and its surface hardness is higher than that of oil-resistant rubber, so it is unlikely that the seal members 15 and 17 will be damaged. First, it has sufficient durability, and the side plates 6, 6' can always maintain a proper sealing action.

Since the gear pump motor according to the present invention is for both forward and reverse rotation, it goes without saying that it can be used as is for either one of the rotations. Furthermore, in the above explanation, we have described a gear pump motor using a movable side plate that is integrated with bearing bushes 6 and 6' that are equipped with both bearings 11 and 12 for the driving shaft 1 and the driven shaft 3. The bearing bushes 6, 6' and separate movable side plates are connected to the gears 2, 4 and the bearing bushes 6, 6'.
The same thing can be said about the gear pump/motor installed between the two.

〔Effect of the invention〕

As is clear from the above description, the gear pump or motor according to the present invention has a high pressure chamber connected to the high pressure side, a low pressure chamber connected to the low pressure side, and a medium pressure fluid between these pressure chambers. The three medium pressure chambers into which is introduced are provided with a figure-eight groove around the shaft hole on the opposite side of the side plate from the side that abuts the side surface of the gear, and a figure-eight groove connected to the groove above and below this groove, respectively. Since it is formed by fitting an endless seal member into a shaped groove and an end seal member partially overlapping with the endless seal member into the above-mentioned dogleg groove, it is possible to eliminate the problem of the conventional seal member with ends. Damage to the endless seal member caused by repeated local compression due to pressure deformation of the end surface is eliminated, and the endless seal member and the end seal member can be used to seal the low pressure chamber and medium pressure chamber without mutual pressure influence. Since high pressure chambers are formed, there is no pressure imbalance between the pressure in these chambers and the pressure on the gear side of the bearing bushing, and therefore the side surface of the bearing bushing exerts a braking action on the side surface of the gear. Since the seal members are not damaged by the friction between the seal members that occurs when the gear pump/motor is repeatedly started and stopped, it is possible to maintain good operating performance over a long period of time. can.

[Brief explanation of the drawing]

Figure 1 is a side sectional view of the gear pump/motor, Figure 2
The figure is a front view of a side plate integrated with a conventional bearing bush, and Figure 3 is a partial sectional view showing its cross section.
FIG. 4 is a front view of another conventional side plate integrated with a bearing bushing, FIG. 5 is a partial sectional view showing the cross section thereof, and FIG. 6 is a side plate integrated with a bearing bushing of an embodiment of the present invention. A front view of the side plate, and FIG. 7 is a partial cross-sectional view showing a cross section thereof. 2... Main drive gear, 4... Driven gear, 5... Casing, 6, 6'... Side plate integrated with bearing bushing, 15... Endless seal member, 16... Pressing member, 17... Ended seal Member, 18... Pressing member, A... Low pressure side, B... High pressure side, H... High pressure chamber, L... Low pressure chamber, M... Medium pressure chamber.

Claims (1)

[Scope of Claims] 1 A pair of gears are fitted into holes connected to a suction port and a discharge port of hydraulic oil in a casing, and are configured to mesh with each other to rotate. In a gear pump or motor having a side plate that abuts to seal a side surface of a gear, a high pressure side plate is connected to a high pressure side and a low pressure side of a meshing portion of the gear on a side opposite to the side of the side plate that abuts the side surface of the gear, respectively. and a low pressure chamber, and a medium pressure chamber between these two pressure chambers, an "8" shaped groove around the shaft hole is provided in the side plate, and a groove in the longitudinal direction of the side plate is provided at both longitudinal ends of the side plate. symmetrically with respect to the line, each pair of "shi" shaped grooves are connected to a part of the "8" shaped groove on the back side of the "shi" shape, and each pair of "shi" shaped grooves are ”-shape to surround predetermined areas at both ends in the longitudinal direction of the side plate, and an endless seal member is housed in the “8”-shaped groove, and an end seal member is housed in each of the “8”-shaped grooves. It is formed by overlapping both seal members so that a part of the outer peripheral surface of the "8" shaped endless seal member is in close contact with the back side surface of each "8" shaped end seal member. A gear pump or motor featuring: