JPH0249410B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a hydraulic switching valve for a reciprocating hydraulic cylinder that drives a working machine installed in an agricultural tractor, a construction tractor, or the like.

(Prior Art) To explain a conventional example of an agricultural tractor, as shown in FIG.
A single-acting cylinder system is often adopted, which is driven by a single-acting hydraulic cylinder d that is operated by the hydraulic switching valve e in B and C. In this system, the hydraulic switching valve e is set to position A, that is, the neutral position, and the single-acting Fixing the working machine c by fixing the expansion and contraction of the hydraulic cylinder d, moving the working machine c to position B and extending the cylinder d to raise the working machine c, and setting the working machine c to position C with the cylinder d free to extend and contract, and making the working machine c float; In addition, the lowering of work equipment c is performed by the work equipment's own weight, so that when work equipment c receives an excessive load reaction force in the upward direction,
It is characterized by the fact that it can be placed in a floating state and the hydraulic mechanism is simplified.

In addition, recently, with the diversification of work equipment and work content (e.g. root removal work equipment, subsoilers, etc.),
It is also necessary to forcibly lower the work equipment using hydraulic pressure, and the double-acting hydraulic cylinder _d1 shown in Fig. 2 is sometimes used, but the hydraulic switching valve _e1 that operates it is operated as shown in the figure. Machine C cannot be left floating.

(Problem to be Solved by the Invention) The specifications of the conventional hydraulic switching valve of the hydraulic cylinder can be changed to a hydraulic switching valve or hydraulic cylinder as shown in FIG. 1 or 2 depending on the operation of the work machine, etc. There are some drawbacks that require

In addition, a 4-position hydraulic switching valve was developed, with a cylinder retracted position and a cylinder extended position on both sides of the neutral position, and a floating position outside the cylinder extended position.
However, in this hydraulic switching valve, the direction in which the plunger is operated from the neutral position to the cylinder retracted position or the cylinder extended position is different from the direction in which the plunger is operated from the floating position to the cylinder retracted position or the cylinder extended position, resulting in incorrect operation. When switching from the floating position to the cylinder shortened position or extended cylinder position, it is necessary to temporarily switch to the opposite cylinder extended position or cylinder shortened position, which poses problems in switching operability and smoothness of operation, causing problems in the work equipment. When working in a floating state, there are problems such as hindering or adversely affecting the floating work.

(Means for Solving the Problems) The present invention provides a reciprocating hydraulic cylinder that is installed in both oil passages on the head side and rod side of a reciprocating hydraulic cylinder that switches and drives a working machine between fixed, floating, ascending, and descending modes. In a hydraulic switching valve that switches between fixed, telescopic, and extending and shortening oil passages, the holes in the valve body have pressure oil ports in the center that communicate with the hydraulic pressure supply source and are spaced sequentially from the center to the right and left. , right and left inner tank oil ports communicating with the oil tank, right and left outer pressure oil ports communicating with the hydraulic supply source, and right and left head side oil ports and rods communicating with the reciprocating hydraulic cylinder. side oil port,
Right and left outer tank oil ports communicating with the oil tank are provided, and a plunger that slides in four positions within the hole is connected to the central pressure oil port and both inner tank oil ports at land intervals. The right and left sides communicate with two circumferential grooves that switch between the two circumferential grooves, and the oil passages that switch between the two outer pressure oil ports, the two outer tank oil ports, the head side oil port, and the rod side oil port. Two sets of four circumferential grooves are provided, and each of the oil ports, each of the circumferential grooves, and the passage form a telescopically fixed and retractable oil passage on the center side of the plunger, and the right It is characterized by a configuration with a four-position switching oil passage that forms extension and contraction oil passages on the left side, and nine oil ports arranged at intervals in the hole of the valve body and land spacing in the plunger. Six circumferential grooves and passages arranged at different angles form fixed and extendable oil passages on the center side of the plunger, and extendable and shortened oil passages are switched on the right and left sides. By making it possible to configure the position switching oil path and diversifying the functions of the hydraulic switching valve,
The operating performance of the reciprocating hydraulic cylinder and the driving performance of the work machine using the reciprocating hydraulic cylinder are improved.

(Function) When the plunger is placed in the center telescopically fixed position (neutral), the pressure oil supplied from the hydraulic supply source is drained to the oil tank through the passage of the pressure oil port → circumferential groove → tank port, and the head side oil The head side and rod side of the reciprocating hydraulic cylinder are shut off by the port and the rod side oil port to create a sealing pressure, the reciprocating hydraulic cylinder is telescopically fixed, and the working machine is fixed and held.

When the plunger is slid from the telescopic fixed position to one side (to the left), the pressure oil supplied from the hydraulic supply source is transferred to the head side of the reciprocating hydraulic cylinder through the passage of pressure oil port → circumferential groove → head side oil port. The hydraulic oil on the rod side of the reciprocating hydraulic cylinder is
The oil is drained into the oil tank through the passage from the head side oil port to the circumferential groove to the tank oil port, and the reciprocating hydraulic cylinder is extended, that is, the working machine is raised to the extended position.

When the plunger is slid from the telescopic fixed position to the other side (right side in the figure), the pressure oil supplied from the hydraulic supply source is drained into the oil tank through the passage of the pressure oil port → circumferential groove → tank oil port, and reciprocates. Hydraulic oil on the head side and rod side of the hydraulic hydraulic cylinder is connected to the head side oil port and rod side oil port → (oil path)
→The oil tank can be freely drained through the passage of the tank oil port, and the reciprocating hydraulic cylinder can be expanded and contracted, that is, the working machine can be freely floated in a telescopic position.

When the plunger is further slid from the telescopic position to the other side (to the right) and switched in two steps, the pressure oil supplied from the hydraulic supply source reciprocates in the passage from the pressure oil port → circumferential groove → rod side oil port. Hydraulic oil is supplied to the rod side of the hydraulic hydraulic cylinder, and the hydraulic oil on the head side of the reciprocating hydraulic cylinder is drained into the oil tank through the passage of the head side oil port → circumferential groove → oil passage → tank oil port, and the reciprocating hydraulic oil is The cylinder is retracted, ie in a retracted position, and the implement is lowered. Note that the extended/contracted position and the contracted position can also be arranged in the opposite direction.

As mentioned above, four-position operation is possible: fixing and holding the work equipment in the telescopic fixed position, floating the work equipment in the telescopic position, raising the work equipment in the extended position, and lowering the work equipment in the retracted position. Also, the extended position (raised) ←→ fixed extension (fixed,
Switched to 4-position operation in the order of (neutral) ← → telescopic position (floating) ← → shortened position (lowered) (extended and shortened positions can be designed in reverse), from telescopic fixed (fixed, neutral) to extended position, The direction in which the plunger is operated from the retracted position matches the direction in which the plunger is operated from the telescopic position (floating) to the extended and retracted positions,
When switching from the telescopic position (floating) to the extended position or the shortened position, the switch can be made directly without temporarily switching back to the shortened or extended position, eliminating erroneous operations and allowing the switching operation to be carried out smoothly. Ru.

(Embodiment) An embodiment of the present invention is shown in FIGS. 3 to 7, in which A is a tractor main body, and C is a tractor main body A.
A work machine attached to the rear of the machine via a lifting mechanism B,
D is a reciprocating hydraulic cylinder disposed on the tractor body A, and E is a hydraulic switching valve, which drives the reciprocating hydraulic cylinder D by switching between fixing, floating, raising, and lowering the head and rod sides of the reciprocating hydraulic cylinder D. A hydraulic switching valve E is provided for switching the reciprocating hydraulic cylinder D, which is interposed between the two oil passages, into telescopic fixed, telescopic, and extending and shortening oil passages.

To explain the hydraulic switching valve E, as shown in FIG.
It has a hole 2 bored in the hole 2 and a plunger 3 that is slid to four positions within the hole 2, and nine oil ports 2-1, 2-2...2 are provided at intervals in the hole 2. -9 are provided, lands 4, 5...11 are formed on the plunger 3, and six circumferential grooves 3-1,
3-2...3-6 are provided, and the plunger 3 has a pressure port 41 communicating with the hydraulic pressure supply source, tank ports 42 and 43 communicating with the oil tank, and communicating with the rod side and head side of the reciprocating hydraulic cylinder D. cylinder connection ports 44 and 45 are provided, and the pressure port 41 is an oil path and is connected to oil ports 2-3, 2-5,
2-7, the tank port 42 communicates with the oil ports 2-1 and 2-9 through an oil passage, and the tank port 43
communicates with the oil ports 2-4, 2-6, the cylinder connection port 44 communicates with the oil port 2-8, the cylinder connection port 45 communicates with the oil port 2-2, and the circumferential groove 3-1. 3-2 communicate with each other through an oil passage 39, and the circumferential grooves 3-5 and 3-6 communicate with each other through an oil passage 36.

That is, the pressure oil ports 2-5 in the center are connected to the hydraulic pressure supply source at intervals sequentially from the center to the right and left in the hole 2 of the valve body 1, and the right and left inner tank oil ports are connected to the oil tank 43. Port 2-4, 2-
6, right and left outer pressure oil ports 2-3, 2-7 communicating with a hydraulic pressure supply source, and a reciprocating hydraulic cylinder D.
The right and left head side oil ports 2-2 and rod side oil ports 2-8 communicate with the oil tank 42, and the right and left outer tank oil ports 2-1, 2- communicate with the oil tank 42.
9 is provided, and the plunger 3 that slides in four positions in the hole 2 is used to switch between the pressure oil port 2-5 in the center and both inner tank oil ports 2-4, 2-6 with land intervals. Two circumferential grooves 3-3, 3-4,
an oil passage 36 for switching between both outer pressure oil ports 2-3, 2-7 and both outer tank oil ports 2-1, 2-9 and head side oil port 2-2 and rod side oil port 2-8; 4 circumferential grooves 3-1, 3-2, 3-5, 3-, two on the right and two on the left, communicating at 39
6, and the oil ports, the circumferential grooves, and the oil passages form extendable fixed and extendable oil passages on the center side of the plunger 3, and extendable and shortened oil passages are provided on the right and left sides. This is a hydraulic switching valve for a reciprocating hydraulic cylinder that is provided with four-position switching oil passages formed by switching the oil passages.

The embodiment of the present invention has the above-mentioned configuration, and its operation will be explained (each oil port and each circumferential groove will be explained using simple names). FIG. ), the pressure oil supplied from the hydraulic supply source flows through the passage of pressure port 41 → oil port 2-5 → circumferential groove 3-3 → oil port 2-4 → tank port 43. The oil is drained into the tank, and the head side and rod side of the reciprocating hydraulic cylinder D are shut off at the oil ports 2-2 and 2-8 to create a sealing pressure, and the reciprocating hydraulic cylinder D is in the telescopic and fixed position, and the work machine C is Fixed, held.

Next, when the plunger 3 is slid from the telescopically fixed (neutral) position shown in Fig. 4 to the left in the figure by a specified stroke, it becomes as shown in Fig. 5, and the pressure oil supplied from the hydraulic supply source is transferred to the pressure port. 41 → Oil port 2-3 → Circumferential groove 3-1 → Oil port 2-2 → Reciprocating hydraulic cylinder D in the passage of cylinder connection port 45
The hydraulic oil on the rod side of the reciprocating hydraulic cylinder D is supplied to the head side of the reciprocating hydraulic cylinder D through the cylinder connection port 44→
Oil port 2-8 → Circumferential groove 3-5 → Oil port 2-9
→The oil is drained into the oil tank through the passage of the tank port 42, and the reciprocating hydraulic cylinder D is operated in extension, that is, the passage is switched to the extension passage, and the working machine C is raised.

In addition, the telescopic fixed position (neutral) shown in FIG.
When the plunger 3 is slid from the position to the right in the drawing by a specified stroke, the state shown in FIG. 6 is achieved, and the pressure oil supplied from the hydraulic supply source is
→ Oil port 2-5 → Circumferential groove 3-4 → Oil port 2-
6 → The hydraulic oil on the rod side and head side of the reciprocating hydraulic cylinder D is drained to the oil tank through the passage of the tank port 43, and is transferred to the cylinder connection port 44 →
Oil port 2-8 → oil passage 36 → oil port 2-9 → passage of tank port 42, and cylinder connection port 45 → oil port 2-2 → circumferential groove 3-1 → oil port 2-1 → tank port 42 Through the passageway, the drain connected to the oil tank becomes freely available, and the reciprocating hydraulic cylinder D becomes freely extendable and retractable, that is, the working machine C is floated in a telescopic position.

When the plunger 3 is further slid from the telescopic position shown in FIG. 6 to the right side in the figure by a specified stroke, the state shown in FIG. ―
7→Circumferential groove 3-5→Oil port 2-8→Cylinder connection port 44 passage supplies the hydraulic oil of reciprocating hydraulic cylinder D to the rod side of reciprocating hydraulic cylinder D. Port 2-2
→ Circumferential groove 3-2 → Oil passage 39 → Oil port 2-1 → Drained to the oil tank through the tank port 42 passage,
The reciprocating hydraulic cylinder D is shortened, ie, is in the shortened position, and the work implement C is lowered.

As described above, the oil ports, circumferential grooves, and oil passages form fixed and extensible oil passages on the center side of the plunger 3, and extendable and shortened oil passages are formed on the right and left sides. Four position switching oil passages are formed.

(Effects of the Invention) The present invention has the above-mentioned configuration, and by sliding the plunger in four positions, the reciprocating hydraulic cylinder can be moved from the extended position (raised position of the work equipment) to the telescopic fixed position (fixed position of the work equipment, neutral position) ) ←→ telescoping position (floating of the work equipment) ←→ shortened position (lowering of the work equipment) (the extended position and the shortened position can be reversed) constitutes a switching oil path that can be switched to 4-position operation. The direction in which the plunger is operated from the fixed position to the extended or shortened position is the same as the direction in which the plunger is operated from the free telescopic position to the extended or shortened position to prevent erroneous operation and to prevent movement from the freely telescopic position to the extended or shortened position. When switching to the retracted or extended position, the switch is operated directly without the need for a temporary switch to the opposite retracted or extended position, and the switch is directly moved to the required retracted or extended position without interfering with or adversely affecting the floating operation. Switching is performed smoothly, preventing erroneous operation, and significantly improving switching performance, reliability, and operability, and greatly increasing work efficiency.

Despite having the above effects,
The mechanism is greatly simplified and miniaturized, and it has versatility for use with various working machines, and is provided at low cost.

[Brief explanation of drawings]

FIG. 1 is a side view mechanism diagram showing a conventional example, FIG. 2 is a side view mechanism diagram showing another conventional example, FIG. 3 is an overall side view mechanism diagram showing an embodiment of the present invention, and FIG. 4 is an enlarged vertical sectional view of the hydraulic switching valve in Fig. 3, and Figs. 5 to 7 are
The figures are enlarged longitudinal cross-sectional views showing each function of the hydraulic switching valve. C: Work equipment, D: Reciprocating hydraulic cylinder, E: Hydraulic switching valve, 1: Valve body, 2: Hole, 2-
1, 2-4, 2-6, 2-9: Tank port, 2
-2: Head side oil port, 2-3, 2-5, 2-
7: Pressure oil port, 2-8: Rod side oil port,
3: Plungeya, 3-1, 3-2, 3-3, 3-
4, 3-5, 3-6: Circumferential groove, 36, 39: Passage.

Claims (1)

[Claims] 1. A reciprocating hydraulic cylinder is installed in both oil passages on the head side and rod side of a reciprocating hydraulic cylinder that switches and drives the work equipment between fixed, floating, raising and lowering, and the reciprocating hydraulic cylinder can be fixed, telescopic, telescopic, extendable and shortened. In a hydraulic switching valve that switches to an oil passage, there are pressure oil ports in the center that communicate with the hydraulic supply source at intervals sequentially from the center to the right and left, and inner tanks on the right and left that communicate with the oil tank. an oil port, right and left outer pressure oil ports communicating with the hydraulic pressure supply source, right and left head side oil ports and rod side oil ports communicating with the reciprocating hydraulic cylinder, and a right side oil port communicating with the oil tank; A left outer tank oil port is provided, and a plunger that slides in four positions within the hole is used to switch between the central pressure oil port and both inner tank oil ports at land intervals.
A set of two right and two left right and left circumferential grooves communicating with each other through an oil passage that switches between the two outer pressure oil ports, the two outer tank oil ports, the head side oil port, and the rod side oil port. Four circumferential grooves are provided, and the oil ports, the circumferential grooves, and the passages form oil passages that are extendable and fixed on the center side of the plunger, and extendable on the right and left sides. A hydraulic switching valve for a reciprocating hydraulic cylinder, characterized in that a four-position switching oil passage is provided to form a shortened and shortened oil passage.