JP3462978B2 - Lubrication structure of swash plate type double piston pump - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a swash plate type piston pump used for construction machines and the like, and more particularly to preventing a failure due to wear powder or the like generated in a pump operating mechanism. The present invention relates to a lubricating structure in a swash plate type dual piston pump which can prevent a rise in oil temperature in a casing caused by a stirring resistance of lubricating oil by a rotating member and a gear mechanism. 2. Description of the Related Art Conventionally, there has been known a rotary piston type swash plate type dual piston pump in which two pump units are housed and arranged in a single pump body. In this type of pump, the rotating shafts of two cylinder blocks arranged in parallel are connected via gears, and one of the rotating shafts is driven as a drive shaft, whereby the two cylinder blocks are integrally formed. It is configured to rotate. In this type of swash plate type dual piston pump, when the rotating shafts are connected via gears,
Space for installing gears on the rotating shaft is required,
There is a problem that the axial length of the pump is longer than that of a single piston pump, and the entire structure is large. [0004] From such a viewpoint, conventionally, a gear for transmitting a rotational force is formed on the outer peripheral portion of a cylinder block, and the length of the rotary shaft is reduced without forming a gear on the rotary shaft. The structure can be miniaturized, and the axial distance between the point of application of the rotational force acting on the cylinder block and the rotational reaction force can be kept small to suppress the generation of a tilting moment inside the cylinder block. There has been proposed a swash plate type double piston pump configured to obtain a mechanically stable structure (Japanese Utility Model Application Laid-Open No. 2-102).
No. 35981). However, in the swash plate type double piston pump according to the above proposal, the cylinder block is driven by the drive shaft, and is slidably incorporated into a plurality of piston holes provided in the cylinder block in the axial direction. With the reciprocating movement of the piston, suction and discharge are performed to a space formed between the piston and the piston hole of the cylinder block via an oil passage provided in the port plate to perform a pump operation. . However, in the swash plate type dual piston pump of the prior art, when the driving force from one pump to the other pump is transmitted via a gear mechanism provided on the outer peripheral portion of each cylinder block, Although the pump is miniaturized as a dual pump, this cylinder block receives a radial force or a frictional force for transmitting the driving force on the meshing portion of the gears in addition to the hydraulic pressure. The balance between the hydraulic pressure generated in the piston hole located on the side and the separating force generated by the flow of high-pressure oil or high-pressure oil acting on the high-pressure port on the sliding surface between the cylinder block and the port plate is lost. As a result, the cylinder block cannot be properly hydraulically floated, and in the worst case, the sliding surface between the port plate and the cylinder block may open. My, there is a danger that the pump function is lost. As a countermeasure, if the hydraulic pressure is set to be larger than the separating force, it is possible to prevent the cylinder block from being lifted up. There is fear. For this reason, it was extremely difficult to put the swash plate type piston pump in the prior art to practical use. [0008] From such a viewpoint, the present applicant firstly
In order to overcome all the problems in the prior art and obtain a highly reliable swash plate type dual piston pump that can be reduced in size and improve pump performance, a pair of rotating shafts are arranged in parallel and close to each other. The cylinder block integrally formed with the rotating shaft is provided with a gear mechanism on the outer peripheral portion thereof and mutually connected, and a driving force applied from the rotating drive mechanism to one rotating shaft is applied to the other rotating shaft via the gear mechanism. In a swash plate type dual piston pump configured to transmit and simultaneously drive two pumps, a casing of the pump is constituted by a housing surrounding a swash plate side and a cover surrounding a port plate side. Another pump is attached to a part of the cover on the extension of the rotating shaft to perform a pump operation by a common rotating shaft, and further attached to the cover. A relief valve for regulating the discharge pressure of the pump is provided on the cover, and a spring is provided on the holding surface side of the port plate which is slidably and liquid-tightly abutted against the cylinder block performing the pump operation. By providing a pressing means by force and oil pressure to press the port plate against the sliding surface of the cylinder block, the length of the rotating shaft in the length direction is set short,
The compact size ensures smooth transmission of the pump driving force from the rotating shaft, and ensures sufficient liquid tightness in the sliding part.
We have developed a highly reliable swash plate type dual piston pump that can exhibit the required pump performance and filed a patent application (Japanese Patent Application No. 9-100591). [0009] However, in the swash plate type dual piston pump having the above-described structure, the lubricating oil in the casing is circulated by an internal leak of the working oil filled before the start, and is supplied to the tank. It is a return structure, in which the amount of circulated oil is small. As described above, in the swash plate type dual piston pump according to the above proposal, since the amount of lubricating oil in the casing returning to the tank is small, abrasion powder and the like generated inside the casing enter the sliding surface and are seized. And abnormal wear. In addition, the oil stirring resistance of the gear mechanism causes the temperature of the lubricating oil in the casing to rise in a short time, thereby deteriorating the working oil, insufficient lubrication of the sliding surface,
There is a problem that inconveniences such as curing of the seal parts occur. The inventors of the present invention have conducted intensive studies and as a result, have found that the casing of the pump is composed of a housing surrounding the swash plate side and a cover surrounding the port plate side. Another pump is mounted on a part of the cover to perform a pump operation by a common rotary shaft, and a relief valve for regulating the discharge pressure of the other pump mounted on the cover is provided on the cover. And a return oil passage for the relief valve is provided in the cover so that the return oil of the relief valve flows into a position on the swash plate side of the meshing portion of the gear mechanism in the casing. And a drain port is provided at a position on the cover side near the port plate at the back of the gear mechanism to discharge the return oil of the relief valve. Failure due to wear powder generated in the casing and the temperature rise of the lubricating oil in the casing,
It has been found that it is possible to obtain a lubricating structure in a swash plate type dual piston pump which can effectively prevent each of them. Accordingly, it is an object of the present invention to prevent a failure due to abrasion powder or the like generated by a pump operating mechanism in a casing, and to prevent an increase in oil temperature caused by a stirring resistance of lubricating oil by a rotating member and a gear mechanism. Another object of the present invention is to provide a lubricating structure in a swash plate type dual piston pump which can be achieved appropriately and smoothly. In order to achieve the above object, a lubricating structure for a swash plate type dual piston pump according to the present invention has a pair of rotating shafts arranged in parallel and close to each other.
A syringe with a gear mechanism on the outer circumference for each of the rotating shafts
Dublock is applied to the radial and frictional forces from the gear mechanism.
Reliable positioning in the radial and axial directions even when the
And a swash plate type double unit configured to transmit a driving force applied to one rotation shaft from the rotation drive mechanism to the other rotation shaft via the gear mechanism to simultaneously drive the two pumps. A casing of the pump is constituted by a housing surrounding the swash plate side and a cover surrounding the port plate side, and another pump is mounted on a part of the cover on the extension of one rotation shaft. A swash plate type dual piston pump, wherein the cover is provided with a relief valve for regulating the discharge pressure of another pump attached to the cover, wherein the pump operation is performed by a common rotary shaft. A return oil passage for the relief valve is provided in the casing so that the return oil of the relief valve flows into a swash plate side position where the gear mechanism in the casing meshes. Provided drain port on the cover side position near the port plate of the gear mechanism back of the casing, characterized by being configured to discharge the return oil of the relief valve. Next, an embodiment of a lubricating structure in a swash plate type dual piston pump according to the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 shows an embodiment of a swash plate type dual piston pump according to the present invention. That is, the swash plate type dual piston pump in this embodiment is basically
A pair of swash plates 12a and 12b are provided for sliding contact with the inner surface 10a of the housing 10, respectively.
b is inserted so as to be tiltable at right angles to the axial direction of the rotating shafts 14a and 14b. The one rotating shaft 1
Reference numeral 4a denotes a drive shaft, one end of which protrudes out of the housing 10, and is configured to be appropriately connected to a rotary drive mechanism. The rotary shafts 14a, 14b are provided with cylinder blocks 16a, 16b integrally therewith, and a plurality of pistons 18 are slidably movable in the direction of the rotary shaft with respect to these cylinder blocks 16a, 16b. Incorporate tightly. Each piston 18 has a ball head 18a slidably and ball-coupled to a shoe 20, and the shoes 20 are arranged in sliding contact with the sliding surfaces of the swash plates 12a and 12b. Port plates 22 are respectively provided in contact with the suction and / or discharge port side end surfaces of the cylinder blocks 16a and 16b, and the port plates 22 are in contact with and held on the rear surfaces thereof. A cover 24 that surrounds 16a and 16b together with the housing 10 in a liquid-tight manner is attached. The rotating shafts 14a and 14b are mounted on the housing 10 and the cover 24 with the bearings 2 respectively.
It is rotatably supported via 6 and 28. The bearing 26 supported on the housing 10 is
A type that can also support the axial force from the cylinder blocks 16a and 16b is used. However, in the present embodiment, the rotating shaft 14
a, cylinder block 16 integrally formed with 14b
a, 16b are provided on their outer peripheral portions with gear mechanisms 30a,
A gear 30b is provided, and the gear mechanisms 30a and 30b are meshed with each other to rotate integrally. When the thus constructed swash plate type double piston pump is used for a construction machine such as a hydraulic excavator, a pilot pump is required in addition to the swash plate type double piston pump. In this case, the pilot pump 36 is mounted on the cover 24 extending from the rotation shaft 14a of the swash plate type dual piston pump. Therefore, the pilot pump 36 is configured to be driven by the rotating shaft 14a of the swash plate type dual piston pump. The suction port 36a of the pilot pump 36 and / or
Alternatively, by providing the discharge port 36b inside the cover 24, the size of the pump as a whole can be reduced, and the cost can be reduced by omitting and simplifying piping for installation.
Further, improvement in reliability is easily achieved. In order to regulate the pressure of the pump circuit by the pilot pump 36, a relief valve 38 is provided on the cover 24. With this configuration, the maintenance of the pilot pump is greatly improved and the reliability of this type of pump is improved as compared with the case where the relief valve is mounted on the casing of the pilot pump as seen in the prior art. It is planned. According to the present invention, in the swash plate type dual piston pump having the above structure, the return oil from the relief valve 38 of the pilot pump 36 is returned into the cover 24 to which the relief valve 38 is attached. 4
0a, the return oil passage 40a is further extended to communicate with the inside of the housing 10, and the return oil passage 40b provided in the housing 10 is connected to the gear mechanism 3 in the casing.
An opening is formed so that the return oil flows into a position on the side of the swash plate 12a or 12b where the first oil and the second oil 30a mesh with each other. The cover 24 has a port plate 22 at the back of the gear mechanisms 30a and 30b in the casing.
A drain port 42 is provided corresponding to the position on the cover 24 side close to the above, and the return oil of the relief valve 38 is discharged. With this configuration, the return oil from the relief valve 38 of the pilot pump 36 flows into the casing through the return oil passages 40a and 40b, and is discharged from the drain port 42 to the tank side. You. Then, the return oil that has flowed into the casing can pass through the portion where the gear mechanisms 30a and 30b mesh with each other in the axial direction and circulate in the casing in a certain direction. When the pilot pump 36 is used as a pilot pressure source, the relief valve 38 is always operated when the swash plate type dual piston pump is driven, and the relief valve 38 returns to the return oil passages 40a and 40b. The oil continues to flow. Next, the operation of the swash plate type dual piston pump according to this embodiment having the above-described configuration will be described together with a more detailed configuration. First, when one of the rotary shafts 14a is driven to rotate by a drive mechanism (not shown), this rotary drive force is transmitted to one of the cylinder blocks 16a integrally formed with the rotary shaft 14a. At the same time, the gear mechanism 30 provided on the outer circumference of each cylinder block 16a, 16b
a and 30b are also transmitted to the other cylinder block 16b. However, each of the cylinder blocks 16a, 1
6b is integrally formed with the rotating shafts 14a and 14b, and the respective rotating shafts 14a and 14b, that is, the cylinder blocks 16a and 16b are reliably supported by bearings 26 and 28 mounted on the housing 10 and the cover 24. Then, the port plate 22 is moved toward the sliding surfaces of the cylinder blocks 16a and 16b which are securely supported.
Since the hydraulic block floats while being pressed, even if a radial force or a frictional force from the gear mechanisms 30a, 30b acts on the cylinder blocks 16a, 16b due to the transmission of the rotational driving force, the cylinder block 16a, 16b can be moved radially and axially. With respect to the cylinder blocks 16a and 16b which are securely positioned in
By setting the lightweight port plates 22 to be pressed against each other, the pump function and its performance are not affected at all, and extremely high reliability can be obtained as compared with the prior art. In particular, in the present invention, the return oil passages 40a and 40b and the drain port 42 provided in the casing are provided.
As a result, the return oil of the relief valve 38 flows into the casing, and the oil always flows in a fixed direction to the portion where the gear mechanisms 30a and 30b mesh with each other. And wear powder generated by a gear mechanism or the like is removed from the piston 1.
It is possible to effectively prevent adverse effects on the sliding surfaces such as the shoe 8 and the shoe 20. In this embodiment, the rotation shafts 14a,
14b and the cylinder blocks 16a and 16b are shown as integrally formed by separate members, respectively.
The driving force from the rotating shafts 14a, 14b is applied to the rotating shafts 14a, 14b by the splines 17a, 17b provided on the inner diameter portions 15a ', 15b' of the cylinder blocks 16a, 16b.
Is transmitted by a spline connection with Further, each of the cylinder blocks 16a,
A guide portion 15a, 15b in the radial direction with each of the rotating shafts 14a, 14b is provided in a part of the inner diameter of the guide portion 16b.
By setting the radial gap between 5a and 15b very small, even if a radial force acts on the cylinder blocks 16a and 16b, the driving force is reliably transmitted between the cylinder blocks 16a and 16b. Have been. The preferred embodiment of the present invention has been described above. However, the present invention is not limited to the above-described embodiment, and many design changes can be made without departing from the spirit of the present invention. As is apparent from the above-described embodiment, the lubricating structure of the swash plate type dual piston pump according to the present invention has a pair of rotating shafts arranged in parallel and close to each other.
Each with a gear block on the outer periphery
The gear is affected by the radial force and frictional force from the gear mechanism.
Secure radial and axial positioning
The driving force applied to one rotation shaft from the rotation driving mechanism is transmitted to the other rotation shaft via the gear mechanism, and
Swash plate type 2 configured to drive two pumps simultaneously
The casing of the pump is composed of a housing surrounding the swash plate side and a cover surrounding the port plate side, and another pump is mounted on a part of the cover on the extension of one rotation shaft. And a swash plate type dual piston pump configured to perform a pump operation by a common rotary shaft, and further provided on the cover with a relief valve for regulating a discharge pressure of another pump mounted on the cover, A return oil passage for the relief valve is provided in the casing so that return oil from the relief valve flows into a swash plate side position where a gear mechanism in the casing meshes, and a port at the back of the gear mechanism of the casing. By providing a drain port at a cover side position close to the plate and discharging the return oil of the relief valve, the casing Failure or due to wear powder generated at the temperature rise of the lubricating oil in the casing, it is possible to obtain a lubricating structure in the swash plate type twin piston pump can be effectively prevented, respectively.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional side view of a main part of a swash plate type dual piston pump showing one embodiment of a lubrication structure in a swash plate type double piston pump according to the present invention. DESCRIPTION OF SYMBOLS 10 Housing 10a End faces 12a, 12b Swash plates 14a, 14b Rotation shafts 15a ', 15b' Inner diameter parts 15a, 15b Guide parts 16a, 16b Cylinder blocks 17a, 17b Splines 18 Pistons 18a Ball heads 20 Shoes 22 Ports Plate 24 Cover 26, 28 Bearing 30a, 30b Gear mechanism 36 Pilot pump 36a Suction port 36b Discharge port 38 Relief valve 40a, 40b Return oil passage 42 Drain port

Continuation of front page (56) References JP-A-2000-220566 (JP, A) JP-A-10-288148 (JP, A) JP-A-5-87041 (JP, A) JP-A-5-52180 (JP, A) A) Actually open 1987-200107 (JP, U) Actually open 1987-148784 (JP, U) Actually open 1986-10980 (JP, U) Actually open 1979-69165 (JP, U) Actually open 1979 −28101 (JP, U) Japanese Utility Model 7-22076 (JP, U) (58) Fields surveyed (Int. Cl. ⁷ , DB name) F04B 1/00-7/06

Claims (1)

(57) [Claims] [Claim 1] A pair of rotating shafts are closely arranged in parallel,
Each of these rotary shafts has a gear mechanism on the outer periphery.
The cylinder block is driven by radial force or friction from the gear mechanism.
Reliable positioning in the radial and axial directions even when frictional force acts
And configured to be determined, the driving force applied from the rotation drive mechanism on one of the rotating shaft through the gear mechanism is configured to drive the other two pumps is transmitted to the rotary shaft simultaneously <br/> Swash plate type double piston pump, wherein the casing of the pump is composed of a housing surrounding the swash plate side and a cover surrounding the port plate side. The swash plate type 2 is configured such that the pump is mounted and a pump operation is performed by a common rotating shaft, and a relief valve for regulating the discharge pressure of another pump mounted on the cover is provided on the cover.
In the continuous piston pump, a return oil passage of the relief valve is provided in the casing so that return oil of the relief valve flows into a swash plate side position where a gear mechanism in the casing meshes with the casing. A lubricating structure in a swash plate type dual piston pump, wherein a drain port is provided at a position on a cover side close to a port plate at a rear portion of a gear mechanism to discharge return oil from the relief valve.