JP2009236074A - Double gear pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a double gear pump whose components for actualizing the function of controlling the discharge amount of operating liquid in two steps are simplified and built in a body. <P>SOLUTION: Operating oil carried by a high pressure gear pump 21 is delivered from a discharge port 30. In a discharge passage 28, a rod 27 having poppets A, B as valve elements at both ends is energized toward the discharge port 30 in the direction of resisting hydraulic pressure by a spring 26 to change over the discharging direction of the operating oil carried by a low pressure pump 22. When hydraulic pressure in the discharge port 30 is smaller than predetermined, the energizing force of the spring 26 overcomes the hydraulic pressure and the rod 27 is moved toward the discharge port 30 to open a valve with the poppet A on the side of the discharge port 30. On the other hand, when the hydraulic pressure in the discharge port 30 is greater than predetermined, the hydraulic pressure overcomes the energizing force of the spring 26 and the rod 27 opens a valve with the poppet B on the side of a low pressure return port 31 communicated with a suction passage. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a dual gear pump that can be used in various fluid equipment (hydraulic equipment) fields.

  Conventionally, when a gear pump is used alone, it is impossible to control the discharge amount because the pump itself has a fixed capacity.

  In addition, when a variable displacement pump such as a piston pump is used, it is possible to control the discharge amount of the pump itself, but the cost of the pump is high, and its use has caused an increase in cost.

  Therefore, the gear pump is doubled to form a hydraulic circuit as shown in FIG. 1, and the pressure on the discharge port side of the high pressure pump 11 is set as a pilot pressure, and the unload valve 13 is opened so that the pilot pressure is opened when the pilot pressure is higher than a predetermined value. Is provided. When the electric motor 14 is rotated and the high-pressure pump 11 and the low-pressure pump 12 are driven, if the pilot pressure is smaller than a predetermined value, the unload valve 13 is closed and the hydraulic fluid from the high-pressure pump 11 is The hydraulic fluid from the low pressure pump 12 that has passed through the check valve 15 merges and is supplied to the target device (not shown).

  When the pilot pressure is equal to or higher than a predetermined value, the unload valve 13 is opened, and the hydraulic fluid from the low pressure pump 12 passes and is collected in the tank 16. At this time, since the hydraulic fluid from the high-pressure pump 11 is regulated by the check valve 15, it does not flow to the unload valve 13 side but is supplied to the target device.

In Patent Documents 1 and 2, a check valve is provided in the body to prevent the hydraulic fluid from passing through one of the two pumps when collecting the hydraulic fluid from the target device. It is disclosed.
JP 7-332254 A JP 2004-239269 A

  By the way, as shown in the hydraulic circuit of FIG. 1, by combining the check valve 15 and the unload valve 13, the amount of hydraulic fluid discharged from the double gear pump can be reduced according to the pressure supplied to the target device. Although it is possible to control in two stages, the check valve 15 and the unload valve 13 are arranged outside the double gear pump, and parts such as an adapter are necessary, which increases the size and cost of the device. Was inevitable.

  In view of the above-described problems, the present invention has an object to provide a double gear pump built in a body by simplifying components for realizing a function of controlling the discharge amount of hydraulic fluid in two stages. .

  In the present invention, a gear mechanism in which teeth of a pair of gears are engaged with each other is housed in two pump chambers formed on the body and independent of each other to constitute a gear pump, and the drive side of each gear mechanism A double gear pump that couples drive shafts that support the gears of the gears together, conveys the hydraulic oil introduced from the suction port via the suction passage by each gear mechanism, and leads it from the discharge port via the discharge passage. The hydraulic oil conveyed by one gear pump is led out from the discharge port, and the discharge passage is urged by the urging means in a direction against the hydraulic pressure at the discharge port, and valve bodies are provided at both ends. When the rod is configured to switch the discharge direction of the hydraulic oil conveyed by the other gear pump, and the hydraulic pressure of the discharge port is smaller than a predetermined value, the urging force by the urging means wins against the hydraulic pressure, and the rod Move and open the valve on the discharge port side, but if the oil pressure on the discharge port is larger than the predetermined value, the oil pressure will surpass the urging force by the urging means to open the valve on the flow path side where the rod communicated with the suction passage side Configured.

  With the above configuration, it is possible to control the discharge amount in two stages by arranging rods with valve bodies at both ends on the body, so that unitization is possible and parts such as adapters are unnecessary, Space can be saved and costs can be reduced.

  Embodiments of the present invention will be described below with reference to FIGS. The double gear pump of the present embodiment realizes a main body 19 in which functions equivalent to those of a portion surrounded by a two-dot chain line are integrated in the hydraulic circuit shown in FIG.

  FIG. 2A is a cross-sectional view of the double gear pump of this embodiment, and FIG. 2B is a cross-sectional view in the AA direction. The body 20 incorporates a high-pressure pump 22 composed of a pair of gears and a low-pressure pump 22 composed of a pair of gears, and a front cover 23 and a rear cover 24 are mounted on both end faces of the body 20, respectively. Together with the casing. The drive shaft 25 of the high pressure pump 21 is connected to an electric motor (not shown), and is connected to the drive shaft 26 of the low pressure pump 22 by spline coupling or the like. Further, the suction passage 27 and the discharge passage 28 shown in FIG. 2B communicate with the suction port 29 and the discharge port 30 in the high-pressure pump 21 shown in FIG.

  FIG. 3 is a cross-sectional view in the XX direction of FIG. A rod 27 fixed to the other end of a spring 26 whose one end is fixed to a plug 25 screwed to the rear cover 24 is disposed on the discharge side of the low pressure pump 22 in the discharge passage 28.

  Further, at both ends of the rod 27, poppets A and B are formed as valve bodies, and in cooperation with an opening 35 formed on the body 20 and an opening 34 formed on the rear cover 24, one of the two is formed. When the poppet A side is opened, the hydraulic oil discharged from the low pressure pump is merged with the hydraulic oil discharged from the high pressure pump 21 when the poppet A side is opened. On the other hand, when the poppet B side is opened, the hydraulic oil discharged from the low pressure pump 22 is led out from a low pressure return port 31 formed in the rear cover 24 when the poppet B side is opened.

  Next, the operation of the double gear pump of this embodiment will be described with reference to FIGS. When the discharge pressure is equal to or lower than the set pressure, the rod 27 is pushed by the spring 26 and fixed by the poppet B with the valve closed, as shown in FIG. At this time, the valve by the poppet A opens and the discharge passage 28 communicates, so that the discharge flow rates of the high-pressure pump 21 and the low-pressure pump 22 merge and are discharged from the discharge port 30.

  When the discharge pressure is equal to or higher than the set pressure, as shown in FIG. 4, the rod 27 pushes down the spring 26 by the pressure, and the poppet A valve is closed. Therefore, only the high-pressure pump 21 is discharged. At this time, the valve by the poppet B is opened, and the discharge flow rate from the low pressure pump 22 is opened to a low pressure, so that it becomes a no-load state and returns to the low pressure side through the low pressure return port 31.

  In this embodiment, a return pipe (not shown) is used when returning the hydraulic oil discharged from the low pressure return port 31 through the valve of the poppet B to the suction port side or the tank side. As shown in FIG. 6, it is possible to provide the rear cover 24 with the internal passage 32 so as to recirculate to the suction port side of the low-pressure pump.

  Further, in this embodiment, the spring 26 is used as the urging means to set the pressure at which the rod 27 operates, but as a modification thereof, as shown in FIG. 6, the pilot port provided in the rear cover 24 By configuring the hydraulic oil to be introduced from 33, the operating pressure at which the rod 27 operates can be set as a pilot pressure. In addition, the operating pressure at which the rod 27 operates can be similarly set by an electromagnetic operation valve.

  Furthermore, in this embodiment, the high-pressure pump and the low-pressure pump are used, but a pump having the same discharge pressure may be used.

The figure which showed the hydraulic circuit of the present Example. The figure which showed the cross section of the double gear pump of a present Example. The figure which showed the state by which hydraulic oil is discharged from both gear pumps with the double gear pump of a present Example. The figure which showed the state by which hydraulic fluid is discharged from one gear pump with the double gear pump of a present Example. The figure which showed the modification (1) of a present Example. The figure which showed the modification (2) of a present Example.

Explanation of symbols

21 High-pressure gear pump 22 Low-pressure gear pump 26 Spring 27 Rod 28 Discharge passage 30 Discharge port 31 Low-pressure return port

Claims (1)

A gear mechanism in which teeth of a pair of gears are engaged with each other is housed in two pump chambers formed on the body and independent of each other to form a gear pump. It is a dual gear pump that couples the supporting drive shafts to each other, conveys the hydraulic oil introduced from the suction port via the suction passage by each gear mechanism, and leads out from the discharge port via the discharge passage, The hydraulic oil conveyed by one gear pump is led out from the discharge port, and the discharge passage is urged by urging means in a direction against the hydraulic pressure at the discharge port, and a rod provided with valve bodies at both ends. Is configured to switch the discharge direction of the hydraulic oil conveyed by the other gear pump, and when the hydraulic pressure at the discharge port is smaller than a predetermined value, the biasing force by the biasing means wins against the hydraulic pressure and the rod discharges. When the hydraulic pressure of the discharge port is larger than a predetermined value while the valve on the discharge port side is opened, the hydraulic pressure exceeds the urging force by the urging means, and the rod communicates with the suction passage side. A double gear pump characterized in that the valve on the flow path side is opened.

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