JPH0596483U - Hydraulic pump - Google Patents

Abstract

(57) [Summary] [Structure] The hydraulic pump 2 pumps the valve hole 8 of the flow rate control valve 20 for controlling the flow rate from the pump discharge side and the surplus flow rate F from the flow rate control valve 20 into the pump body 3. It has a bypass passage 9 for returning to the side, and this bypass passage 9 is formed by molding at the stage of the rough material.
The bypass passage 9 has an elliptical cross section whose diameter gradually increases toward the outer opening of the front body 5. [Effect] Since a chilled hard layer is formed on the wall surface of the bypass passage, it is possible to suppress the occurrence of erosion or wear, prevent the generation of aluminum pieces, and improve the reliability of the pump body 3. Can be improved.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a hydraulic pump, and more particularly to a hydraulic pump composed of an aluminum die-cast body.

[0002]

[Prior Art]

 In recent years, the body of hydraulic pumps has been manufactured by aluminum die casting in response to the needs for weight reduction. The body of a hydraulic pump is generally constructed by abutting two members, a front body and a rear body. The main body of a hydraulic pump is a cup-shaped front body that houses a pump cartridge consisting of a rotor, a cam ring, and a plate that holds them, and the front body has an opening closed by a rear body. The front body has a built-in flow rate control valve that communicates with the pump discharge side, and a bypass passage that connects the flow rate control valve with the pump suction side is formed. The flow rate control valve controls the flow rate discharged from the pump, and the bypass passage circulates the flow rate overflowed from the flow rate control valve to the pump suction side.

By the way, the bypass passage formed in the front body and the valve hole of the flow control valve are molded by a die by aluminum die casting, and a chilled hard layer is formed on the surface. After that, the chilled hard layer is cut and finished in consideration of the processing accuracy. For this reason, when performing die forming on a die-cast rough material, the die is formed with a diameter smaller than the processing size, and then precision is obtained by machining.

[0004]

[Problems to be solved by the device]

 It is difficult to make the hydraulic pump made of such an aluminum die-cast body extremely thin in terms of size and strength. When the thickness of the aluminum die-cast body of the hydraulic pump increases, defects such as cavities and blowholes tend to occur inside. In addition, aluminum die-cast parts have weak bonding force on the machined surface, in other words, the machined surface is soft, so if the high-speed jet flow continues to flow from the flow control valve into the bypass passage, Erosion or wear occurs due to cavitation on the machined surface, and minute aluminum pieces are generated and mixed in the hydraulic oil, entering the minute clearance where precision is required, causing operational problems. There was a problem. For example, in the flow control valve or the relief valve, the valve stick and the relief valve were left open, and the cartridge part had problems such as seizure.

The present invention has been made to eliminate the above drawbacks, and provides a highly reliable hydraulic pump capable of preventing erosion or wear of the bypass passage and suppressing the generation of fine aluminum pieces. Is.

[0006]

[Means for Solving the Problems]

 A hydraulic pump according to the present invention has a valve hole of a flow rate control valve for controlling a flow rate from a pump discharge side and a bypass passage for returning an excessive flow rate from the flow rate control valve to a pump suction side inside a pump body. The bypass passage is formed by molding at the stage of rough material.

[0007]

[Action]

 In the hydraulic pump according to the above invention, since the bypass passage is formed by molding at the stage of rough material, a chilled hard layer is formed on the wall surface of the bypass passage. Even if it is received, it is possible to prevent the occurrence of erosion or wear and prevent the generation of aluminum pieces.

[0008]

【Example】

 The present invention will be described below with reference to illustrated embodiments. 1 to 3 are a longitudinal sectional view showing a hydraulic pump according to an embodiment of the present invention, a cross-sectional view taken along the line II-II in FIG. 1, and a view taken in the direction of arrow III in FIG. As shown in FIG. 1, the main body 3 of the hydraulic pump 2 has a rear body 4 butted against a front body 5 and closed. Inside the cup-shaped front body 5, a pump drive shaft hole 6, a pump cartridge housing hole 7, a valve hole 8 for a flow control valve, and a bypass passage 9 are formed. The pump drive shaft 10 is rotatably fitted in the pump drive shaft hole 6. A pump cartridge 11 is housed in the pump cartridge housing hole 7. The pump cartridge 11 is composed of a rotor 12, a cam ring 13, and a plate 14 that holds them between the rear body 4. The pump drive shaft 10 is integrally rotatably penetrated through the rotor 12, and is driven by the pump drive shaft 10. When the pump drive shaft 10 drives the pump cartridge 11, the hydraulic pump 2 discharges oil to perform a pumping action.

As shown in FIG. 2, the flow rate control valve 20 is composed of a spool 21 slidably fitted in the valve hole 8 of the front body 5. The flow rate control valve 20 is provided between the discharge side of the pump cartridge 11 and a hydraulic device (not shown), and controls the flow rate discharged from the hydraulic pump 2 according to the amount of movement of the spool 21 that slides. Send to hydraulic equipment. Further, the flow control valve 20 causes the overflowed overflow to flow back to the suction side of the pump cartridge 11 (the suction side passage 9A of the rear body 4) via the bypass passage 9.

As shown in FIG. 2, the bypass passage 9 is formed so as to intersect the valve hole 8 from the outside of the front body 5 and open at a predetermined position of the valve hole 8. The bypass passage 9 communicates with the suction side of the hydraulic pump 2 via a suction side passage 9A (see FIG. 1) formed in the rear body 4. A large diameter portion 21A is formed on the spool 2. The large-diameter portion 21A is displaced according to the sliding movement of the spool 21, and opens and closes the opening 30 of the bypass passage 9 at an opening degree corresponding to the flow rate. Therefore, when the flow control valve 20 is operated, the high-speed jet flow F flows into the bypass passage 9 as an overflow overflow in the state where the opening 30 is narrowed by the large diameter portion 21A, and the wall surface of the bypass passage 9 is closed. It hits directly and hits hard. A portion (abutting surface) A1 (a hatched portion in FIG. 3) where the jet flow F directly hits the wall surface of the bypass passage 9 is determined according to the opening degree of the large diameter portion 21A.

By the way, the bypass passage 9 is formed by a die by aluminum die casting, and is formed while leaving a chilled hard layer on the surface. When the bypass passage 9 is molded, the bypass passage 9 is formed such that its diameter gradually increases toward the outside of the front body 5 and, as shown in FIGS. 2 and 3, its cross section has a substantially elliptical shape. After that, in the bypass passage 9, an opening 30 that opens into the valve hole 8 of the flow control valve 20 is formed by machining. The jet 30 flows through the opening 30 only and does not abut. Therefore, the jet flow F overflowing from the flow rate control valve 20 directly hits the position A1 on the wall surface of the bypass passage 9, but since a chilled hard layer is formed at the position A1, cavitation occurs. Can also prevent the occurrence of erosion or wear. Moreover, since the cutting process of the bypass passage 9 is not necessary, the manufacturing cost can be reduced. In addition, the major axis direction of the elliptical cross section of the bypass passage 9 is oriented in the thick lateral direction of the front body 5, and the bypass passage 9 is formed in the thin portion in the upper and lower directions of the front body 5. It is designed to suppress the increase in size.

4 to 7 show various shapes of the bypass passages 109 and 209 at the time of molding the front body 5, respectively, and show the portions A2 and A3 (FIGS. 4 to 6) where the jet F directly hits. The shaded area) is left in a chilled state. Further, the chilled hard layer on the other wall surface may be cut by machining while leaving the portions A 2 and A 3 in the chilled state.

[0013]

[Effect of the device]

 As described above, according to the present invention, erosion or wear of the bypass passage can be prevented, generation of fine aluminum pieces can be suppressed, and reliability of the pump body can be improved.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing a hydraulic pump according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view taken along the line II-II of FIG.

FIG. 3 is a view on arrow III in FIG.

FIG. 4 is an explanatory view showing a cross-sectional shape of a bypass passage during molding of a pump body according to a modified example of the present invention.

5 is a view from the direction of the arrow V in FIG.

FIG. 6 is an explanatory view showing a vertical cross-sectional shape of a bypass passage during molding of a pump body according to a modified example of the present invention.

7 is a cross-sectional view of the bypass passage of FIG.

[Explanation of symbols]

 3 Pump body 8 Valve hole 9 Bypass passage 20 Flow control valve F Overflow (excess flow rate)

Claims (4)

[Scope of utility model registration request] 1. A hydraulic pump having a valve hole of a flow rate control valve for controlling a flow rate from a pump discharge side inside a pump body, and a bypass passage for returning an excessive flow rate from the flow rate control valve to a pump suction side. A hydraulic pump characterized in that the bypass passage is formed by molding at the stage of rough material. 2. The hydraulic pump according to claim 1, wherein the bypass passage is gradually expanded in diameter toward the pump suction side opening. 3. The hydraulic pump according to claim 2, wherein the bypass passage has an elliptical cross section. 4. The hydraulic pump according to claim 1, wherein the bypass passage has an opening formed in the valve hole of the flow control valve by machining.