JPS6347913B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a pump whose discharge amount changes in response to pressure changes, which can be used as a fluid power source for various fluid power sources such as a fluid power lifting jack.

[Prior art] When using a manual pump to feed oil into a hydraulic cylinder, it would be extremely ideal for this type of fluid power source if it could feed as much oil as possible when the load is low, and an appropriate amount when the load increases. .

For example, a fluid power source is known in which two plungers, consisting of a main plunger and a sub-plunger, act simultaneously, and when the load becomes large, one of the plungers is released.

However, this has the drawback that resistance is applied to the relief valve, making lever operation difficult.

5 and 6 show the structure of a fluid pump published in Japanese Patent Publication No. 55-8920, in which a pair of pistons 132 are arranged concentrically and reciprocate within an internal fluid chamber 138 of a housing 140. ,13
4, the piston 132 is provided with a structure carrying a plastic compressible detent ring 142 which acts as a pump actuating rod and moves on either side of an annular ridge 144 on a concentric adjacent piston 134, in the example of FIG. A third pump member 136 is further incorporated on the outside of the piston 134, and the detent ring 142 reciprocates upwardly or downwardly relative to the annular ridge. and retaining ring 14
2 is actuated by the pressure applied to the surface of the piston 132, so the insertion of both pistons 134 and 132,
If the frictional resistance at the time of separation becomes large and the diameter of the piston becomes large as shown in FIG. 5, the raised portion 152 will also need to be large, resulting in poor durability and difficulty in setting the raised portion. In particular, if the cross-sectional area of the pistons 134, 136 is increased, a larger load will be applied to the retaining ring 142, resulting in further deterioration of the conditions, which is undesirable in terms of operation.

[Problems to be Solved by the Invention] An object of the present invention is to reduce the resistance when the two pistons are separated and connected in a pump that can change the discharge amount in response to pressure changes, and in particular to improve durability. Our goal is to provide products with excellent stability.

[Means for Solving the Problems] The means of the present invention includes a sub-plunger that is slidably inserted into the chamber, and a main plunger that is slidably inserted into the sub-plunger and has one end protruding outside the chamber. A spring that acts in the axial direction is attached to one end of a lock pin that is slidably inserted into the hollow part of the main plunger's axis, and the other end is attached to the center hole of the cap bolt fixed to the main plunger. The main plunger is inserted into a state where it can receive the pressure in the working chamber, and lock balls are inserted into the plurality of small holes bored in the hollow part of the main plunger, and the inner circumferential surface of the sub-plunger and the circumferential surface of the lock pin are adjusted to correspond to the pressure change. Lock grooves that engage and disengage the lock ball are formed at respective positions along the circumferential direction.

[Embodiment] In FIGS. 1 to 4, 1 is a chamber, the inside of which is divided into a large diameter part 2 and a small diameter part 3, into which a sub-plunger 4 is slidably inserted. The sub-plunger 4 has a hollow interior and is integrally provided with an annular protrusion 7 that fits into the large diameter portion 2 at one end, and a ring packing 5 is fitted into the annular protrusion 7. A lock groove 8 having a semicircular cross section is formed on the inner surface of the sub-plunger 4 where the annular protrusion 7 is located. Bolt 10 is screwed in. The cap bolt 10 is attached so as to cover the end faces of the main plunger 9 and the sub-plunger 4. The main plunger 9 has a hollow portion 11 formed inside thereof.
A lock pin 12 is housed within. Lock pin 12
is a return spring whose thin end is inserted into the center hole of the cap bolt 10 and is supported by the cap bolt 10 in such a manner that it can receive the pressure in the working chamber of a hydraulic cylinder, etc., and whose elongated other end is housed in the hollow part 11. Supported by 13. An annular lock groove 14 is formed in the lock pin 12. Reference numeral 15 denotes lock balls, which are loosely fitted into small holes 9a bored in three places in the main plunger 9 in order to be removably engaged with the lock grooves 8 and 14. It's starting to combine. In the case of this embodiment, the discharge amount of only the main plunger 9 is selected to be 12.7 cc, and the total discharge amount of the main plunger 9 and the sub-plunger 4 is 62.8 cc. Therefore, the discharge amount ratio between light load and heavy load is 1:5.

[Operation] Suction stroke (state in which the sub-plunger 44 is not activated and is on the right side as viewed in FIG. 1).

When the main plunger 9 moves from left to right and the lock groove 8 of the sub-plunger 4 and the small hole 9a of the main plunger 9 match, the ball 15 that was in the groove 14 of the lock pin 12 is moved to the lock pin 12.
is pushed to the left by the return spring 13, and the pushing force pushes it into the lock groove 8 of the sub-plunger 4. The lock pin 12 continues to advance to the stop position and stops. The main plunger 9 and sub-plunger 4 will not separate unless the lock pin 12 moves to the right again. The amount of oil sucked at this time is equal to the total area of the thick portion of the sub-plunger 4 times the stroke.

Discharge stroke When the load inside the chamber 1 is light When the pressure applied to the tip of the lock pin 12 is lower than the pressure of the spring 13, the ball 15 connects the main plunger 9 and the sub-plunger 4, so the main plunger 9 and the sub-plunger Plunger 4
and simultaneously move toward the left side of the figure as shown in FIG. That is, the discharge amount is five times that of the case where only the main plunger 9 is used. In this case, even if the area of the sub-plunger 4 is increased, the ball 15 will not come off because it is completely connected by the lock pin 12.

Next, when the inside of the chamber 1 is under heavy load, when the spring 13 is compressed by the pressure applied to the tip of the lock pin 12, the lock pin 12 is moved to the position where the lock groove 14 of the lock pin 12 and the small hole 9a of the main plunger 9 match. Moving. At this time, since the sub-plunger 4 is under surface pressure, a force acts to push the ball 15 inward, and the connection between the main plunger 9 and the sub-plunger 4 is released, leaving only the main plunger 9 as shown in FIG. It operates.

[Effects] According to the present invention, the sub-plunger 4 and the main plunger 9 can be moved into the chamber 1 due to the balance between the area and pressure of one end of the locking pin 12 when fitted onto the cap bolt 10 and the elasticity of the return spring 13 at the other end. The operation is stable because the plunger diameter is not affected by simply changing the strength of the spring 13. Also, the lock groove 14 of the lock pin 12
The detachment and coupling action of the sub-plunger 4 can be switched simply by fitting and disengaging the lock ball 15. Therefore, there is no mechanical frictional resistance, the operation is reliable, and the device can withstand long-term use.

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional view of a main part of a pump according to the present invention whose discharge amount changes in response to pressure changes, FIG. 2 is a cross-sectional view taken along line A-A in FIG. 1, and FIGS.
The figure is an explanatory diagram of the action. 5 and 6 are vertical sectional views of a conventional example disclosed in Japanese Patent Publication No. 55-8920. 1... Chamba, 4... Sub plunger, 7...
...Annular protrusion, 8...Lock groove, 9...Main plunger, 9a...Small hole, 12...Lock pin, 1
4...Lock groove, 15...Lock ball.

Claims (1)

[Scope of Claims] 1. A pump whose discharge amount changes in response to pressure changes made up of a combination of the following three elements. (a) A sub-plunger that is slidably inserted into the chamber; and a main plunger that is slidably inserted into the sub-plunger and has one end protruding outside the chamber; (b) The main plunger A spring that acts in the axial direction is attached to one end of the lock pin that is slidably inserted into the hollow part of the shaft center, and the other end is attached to the center hole of the cap bolt fixed to the main plunger to receive the pressure in the working chamber of a hydraulic cylinder, etc. (c) A lock ball is inserted into a plurality of small holes drilled in the hollow part of the main plunger, and the lock ball is inserted in response to pressure changes on the inner circumferential surface of the sub-plunger and the circumferential surface of the lock pin. Lock grooves for engaging and disengaging are formed at respective positions along the circumferential direction.