JPH078849Y2 - Radial plunger pump - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a radial plunger pump.

(Prior Art) As a conventional radial plunger pump, for example, one described in JP-A-58-15770 is known.

This conventional radial plunger pump has a transfer piston (plunger) that is driven by an eccentric cam and is biased by a coil spring, and a cylinder hole that houses this transfer piston is closed by a screw cap.
A pin protruding from the pressure chamber of the transfer piston is provided in order to reduce the dead space of the pressure chamber between the screw cap and the transfer piston. It was in contact.

Therefore, since the head of the pin is in point contact with the screw cap, the pin can easily rotate in the axial direction with respect to the screw cap, which causes the plunger to rotate in the axial direction with a small torque. As a result, various effects such as uneven wear on the contact surface between the plunger and the eccentric cam can be obtained.

(Problems to be Solved by the Invention) However, such a conventional radial plunger pump has the following problems.

That is, since the head of the pin is brought into point contact with the cap, the pin easily tilts around the contact point, and when the coil spring is compressed and shortened, the pin tilts. In some cases, it did not serve as a guide for shortening the coil spring.

In that case, the coil spring may interfere with the plunger, causing a malfunction. In addition, if the coil spring is not shortened in the direction of the winding center axis in this way, a predetermined elastic force may not be obtained when the coil spring is extended next time, which may cause malfunction. .

In addition, as described above, when the pin is tilted, the tip of the pin may come into contact with the coil spring to cause resistance to shortening, which also causes a problem of malfunction.

(Means for Solving Problems) The present invention provides a radial plunger pump having a structure in which the pin is not tilted while the plunger is smoothly rotated, and the above-mentioned problems are not caused. With the goal.

To achieve this object, according to the present invention, a cylinder hole formed in a casing, a cap closing one end side of the cylinder hole, and a cylinder hole slidably accommodated in the cylinder hole from the other end side. A pressure chamber connected to the hydraulic circuit is formed, and is biased in the projecting slide direction by a coil spring interposed between the cap and the cap, and is slid by an eccentric cam provided in contact with the projecting end. A plurality of bearing balls of the plunger, and a plunger having a head interposed between the coil spring and the cap and being in pressure contact with the cap side and having a shaft arranged so that the shaft spring can be extended and contracted. Between the head of the pin and the cap, there is provided a bearing, which is arranged annularly with respect to the shaft center, and which supports the pin rotatably about the shaft center without moving the shaft center. The provision has a means which is characterized in.

(Operation) In the radial plunger pump of the present invention, one end of the coil spring is pressed against the plunger and the other end is pressed against the head of the pin, and the elastic force of the coil spring is the head of the pin and the bearing. Supported by a cap through
It acts in such a direction that the plunger projects from the cylinder hole.

Therefore, the plunger slides by changing the protruding end position based on the drive of the eccentric cam, sucks the working fluid from the hydraulic circuit into the pressure chamber in the process of protruding from the cylinder hole, and retracts into the cylinder hole in the process of retracting. The pressurized hydraulic fluid is discharged into the hydraulic circuit.

The coil spring is expanded and contracted according to the slide of the plunger, and is guided by the shaft portion of the pin so that the expansion and contraction of the coil spring is performed in the direction of the winding center axis. Since the head of the pin is supported by the bearing, it can rotate around the axis, but the axis does not move and always guides the expansion and contraction of the coil spring. The pin reduces the stagnation capacity of the hydraulic fluid in the pressure chamber by the volume thereof.

Also, when the plunger slides due to the eccentric cam,
Due to the contact between the plunger and the eccentric cam, a force component acts around the longitudinal axis of the plunger, and the plunger slides while rotating around the longitudinal axis.

At this time, the rotational force is also transmitted to the coil spring pressed against the plunger from one end side. Therefore, the head of the pin to which the other end of this coil spring is pressed is
Since it is rotatably supported by the bearing, the coil spring and the pin rotate together with the plunger due to the rotational force.

For this reason, the rotation of the plunger is smoothly performed without being hindered by the coil spring and the pin, which allows the protruding end of the plunger to make a good contact with the eccentric cam and also to reduce wear. As a result, changes in the amount of hydraulic fluid being conveyed and changes in pressure are reduced.

Therefore, in the radial plunger pump of the present invention, the plunger can be rotated smoothly,
The expansion / contraction guide of the coil spring is always formed without the pin tilting.

Embodiment An embodiment of the present invention will be described in detail below with reference to the drawings.

First, the configuration of the radial plunger pump A of the first embodiment will be described in detail below with reference to FIG.

The radial plunger pump A according to the first embodiment of the present invention mainly includes a casing 1, a cap 2, a plunger 3, a coil spring 4, an eccentric cam 5, and a thrust bearing 6.

A cylinder hole 11 is formed in the casing 1 in a penetrating state, and a cap 2 is screwed into the upper end portion of the casing 1 in the figure to be closed. An O-ring 12 is provided between the cap 2 and the casing 1.

The plunger 3 is inserted into the cylinder hole 11 from below so as to be slidable in the axial center a direction (vertical direction in the drawing), and the pressure chamber 7 is formed by the plunger 3, the cylinder hole 11 and the cap 2. There is. The plunger 3 has a cylindrical shape, and has an upper end portion opened and a lower end portion closed in the figure, an intake port 32 is opened in the side wall 31, and the lower end portion is a protruding end portion 33 and protrudes from the cylinder hole 11. Has been done.

The pressure chamber 7 is connected to a hydraulic fluid circuit (not shown).
That is, by sliding the plunger 3, the suction port 32
Is opened and closed to communicate with the hydraulic fluid chamber 13 in the casing 1, and is also communicated with the pressurized hydraulic fluid supply passage 15 through the discharge port 14 opened in the cylinder hole 11. A check valve 16 is provided in the pressurized hydraulic fluid supply passage 15 to prevent the pressurized hydraulic fluid from flowing back.

The coil spring 4 is provided on the inner peripheral portion of the plunger 3 such that its winding center substantially coincides with the axis a, and one end thereof is brought into pressure contact with the plunger 3 to urge it in the protruding slide direction. And the protruding end of the plunger 3
An eccentric cam 5 that is in contact with 33 and is rotated by the drive shaft 51 is provided.

That is, the elastic force of the coil spring 4 causes the plunger 3
Is kept in contact with the eccentric cam 5, and the plunger 3 is reciprocally slid in the axial direction a due to the change of the contact peripheral surface due to the rotation of the eccentric cam 5.

Reference numeral 8 denotes a pin, which is provided with a disk-shaped head 81 and a columnar shaft portion 82, and the head 81 is press-fitted and fixed to a lower ring 61 of the thrust bearing 6, and the thrust bearing 6 and the coil spring 4 are used together. The shaft portion 82 is pressed against the cap 2 side, and the shaft portion 82 has a diameter slightly smaller than that of the coil spring 4 so that the coil spring 4 expands and contracts in the direction of the winding center. Is inserted in the coil spring 4 so as to match the winding center and the axis a.

This pin 8 is intended to reduce the stagnation capacity of the hydraulic fluid in the pressure chamber 7 due to its own volume and to guide the expansion and contraction of the coil spring 4.

The thrust bearing 6 supports the pin 8 so as to be rotatable about its axis, and is composed of a lower ring 61, a bearing ball 62 and an upper ring 63, and the upper ring 63 is a head. The elastic force of the coil spring 4 via the portion 81 makes pressure contact with the cap 2 in an end face contact state, and the bearing ball 62 is annularly arranged with respect to the axis a of the pin 8 and the plunger 3.

Next, the operation of the embodiment will be described.

In the radial plunger pump A of the first embodiment, the plunger 3 is reciprocally slid by the rotation of the eccentric cam 5, and the suction port 32 is positioned in the hydraulic fluid chamber 13 by the sliding in the protruding direction. 7, the hydraulic fluid is sucked into the pressure chamber 7. When the plunger 3 slides in and out, the hydraulic fluid in the pressure chamber 7 is pressurized and the discharge port 14
The hydraulic fluid pressurized from is supplied to the pressurized hydraulic fluid supply passage 15, and the above operation is repeated.

The coil spring 4 expands and contracts as the plunger 3 reciprocally slides. The expansion and contraction of the coil spring 4 is always performed in the winding central axis direction by being guided by the shaft portion 82 of the pin 8, and tilts in the radial direction when shortened. It does not move and interfere with the inner peripheral surface of the plunger 3 and the shaft portion 82 of the pin 8 and thus does not adversely affect the operation of the plunger 3.

This is because the end surface of the upper ring 63 of the thrust bearing 6 in which the pin 8 is press-fitted and fixed is in surface contact with the cap 2 and the center axis of rotation does not move.

The pin 8 reduces the stagnation capacity of the hydraulic fluid in the pressure chamber 7 by the volume of the pin 8 so that the air trapped in the pressure chamber 7 when the radial plunger pump A starts to operate. It is significantly reduced and the suction characteristics are improved.

Further, when the plunger 3 slides by the eccentric cam 5, a force component acts around the shaft center of the plunger 3 due to the contact between the plunger 3 and the eccentric cam 5, and the plunger 3 slides while rotating around the shaft center. .

At this time, the rotational force is also transmitted to the coil spring 4 pressed against the plunger 3 from the lower end side. Therefore,
The pin 8 with which the upper end of the coil spring 4 is pressed
Since the head 81 is rotatably supported by the thrust bearing 6, the coil spring 4 and the pin 8 rotate together with the plunger 3 due to the rotational force.

Therefore, the rotation of the plunger 3 is caused by the coil spring 4
It is made smoothly without being hindered by the pin 8 and the pin 8 and thus has the features listed below.

The protruding end portion 33 of the plunger 3 makes good contact with the eccentric cam 5.

The protruding end portion 33 of the plunger 3 is not unevenly worn, and the amount of wear is small.

Since the amount of wear is small, changes in the amount of hydraulic fluid to be conveyed and changes in pressure are also small.

In addition to the features described above, in this embodiment, since the expansion / contraction guide of the coil spring 4 is always formed without the pin 8 tilting or moving, the coil spring 4 interferes with the plunger 3, and the pin 8 Is the coil spring 4
The present embodiment is most characterized in that the above-mentioned characteristics can be obtained at the same time, because the characteristic that it can be prevented from interfering with and causing a malfunction is obtained.

Moreover, in this embodiment, the thrust bearing 6 is formed integrally with the pin 8 and is only pressed against the cap 2. Therefore, assembling work involves inserting the pin 8 as in the conventional case. It has good characteristics and good workability.

Next, a second embodiment shown in FIG. 2 will be described. still,
In describing the second embodiment, the description of the same configuration as that of the first embodiment will be omitted, and the description of the same operation as that of the first embodiment will be omitted.

The radial plunger pump B of the second embodiment is an example in which a radial bearing 260 is used as a bearing that supports the head of the pin 8. As shown, the radial bearing 260 is fitted in the cap 2, and the head 81 of the pin 8 is press-fitted and fixed to the radial bearing 260. The radial bearing 260 is composed of an outer ring 261, an inner ring 262 and a bearing ball 263, and the bearing ball 263 is annularly arranged with respect to the pin 8 and the axis a of the plunger 3.

Therefore, the pin 8 is supported by the radial bearing 260 so as to be rotatable around the shaft center without tilting or shaking.

The embodiment of the present invention has been described in detail above with reference to the drawings. However, the specific configuration is not limited to this embodiment. For example, the embodiment shows an example in which the plunger is provided with an inlet port. A suction port opened and closed by a valve may be provided in the pressure chamber.

(Effect of the Invention) As described above, in the radial plunger pump of the present invention, a plurality of bearing balls are annularly arranged with respect to the shaft center of the plunger, and the pin moves along the shaft center. A bearing that rotatably supports the shaft center without being provided is provided between the head of the pin and the cap,
Although the plunger rotates smoothly, the expansion / contraction guide of the coil spring is always formed without tilting the pin. Effects such as good contact with the eccentric cam at the end, less wear, less change in the discharge amount of hydraulic fluid and less change in pressure pulsation, prevention of interference between the coil spring and plunger due to the pin not tilting, stable expansion and contraction of the coil spring, and As a result, the effect that the operation is stable and the effect that it can be obtained together are obtained.

[Brief description of drawings]

FIG. 1 is a sectional view showing a radial plunger pump of a first embodiment of the present invention, and FIG. 2 is a sectional view showing a radial plunger pump of a second embodiment. 1 …… Casing 2 …… Cap 3 …… Plunger 4 …… Coil spring 5 …… Eccentric cam 6 …… Thrust bearing (bearing) 7 …… Pressure chamber 8 …… Pin 11 …… Cylinder hole 81 …… Head 82 …… Shaft 260 …… Radial bearing (bearing)

Claims (1)

[Scope of utility model registration request] 1. A cylinder hole formed in a casing, a cap for closing one end side of the cylinder hole, a slidably accommodated in the cylinder hole from the other end side, and connected to the cylinder hole to a hydraulic circuit. A pressure chamber is formed, is urged in a protruding slide direction by a coil spring interposed between the cap and the plunger, and is slid by an eccentric cam provided in contact with the protruding end; A plurality of bearing balls annularly with respect to the axial center of the plunger; and a pin that is pressed against the cap side with the head interposed between the spring and the cap, and the shaft is arranged so that the coil spring can be expanded and contracted. And a bearing that supports the pin rotatably around the shaft center without moving the shaft center is provided between the pin head and the cap. Radial plunger pump.