KR20160079488A - Hydraulic System of Transmission for Vehicle - Google Patents

Abstract

The present invention relates to a hydraulic system for a vehicle transmission, capable of forming and keeping lubricating pressure and system pressure by diverging a part of flux from an oil supply line, provided through an existing steering pump and a working machine pump, without installing an extra exclusive oil pump in a hydraulic system for a transmission of a vehicle such as a tractor. The present invention includes: a transmission valve part (20) including a system pressure line and a lubricating pressure line and controlling the operation of a transmission clutch unit (30); a steering oil supply line (61) supplying oil from a steering pump (60) to a steering unit (40); a diverging oil line (63) formed on the steering oil supply line (61) to supply a part of the oil of the steering oil supply line (61) to the system pressure line; a working machine oil supply line (71) supplying the oil from a working machine pump (70) to a working machine unit (100); and a working machine oil diverging line (72) supplying the oil from the working machine oil supply line (71) to the lubricating pressure line.

Description

Technical Field [0001] The present invention relates to a hydraulic system for a vehicle transmission,

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a hydraulic system of a transmission for a vehicle, and more particularly to a hydraulic system of a transmission such as a tractor, To a hydraulic system of a vehicular transmission in which a part of the flow rate is branched so that system pressure and lubrication pressure are formed and maintained.

Generally, a vehicle such as a tractor or a work vehicle is constructed by attaching a work unit such as a plow or a rotary, performing an agricultural work using the power of the engine, attaching a loader or a mower, etc., .

In addition, the tractor or the work vehicle can be driven at various speeds through the engine and the transmission, and automatic transmission technology such as a mechanical transmission type manual transmission or a hydraulic type continuously variable transmission (HST application) is applied.

A hydraulic system of a transmission for a work vehicle such as a conventional tractor will be described with reference to FIG.

5, a conventional hydraulic system includes a steering unit 40 including an HST 10, a shift valve unit 20 and a shift clutch unit 30, for performing a steering operation, And includes a steering pump 60 and a working machine pump 70 that are directly connected to receive power from the engine 50.

The HST 10 basically comprises an HST pump 11 and a motor 12,

Further, the shift clutch unit 30 is provided with a forward-reverse shift clutch 31 and a forward shift clutch 32 (33).

The proportional control valves 21 and 22 and the solenoid direction changeover valves 23 and 24 for supplying the flow rate to the respective shift clutches 31, 25) 26, and when the pressure of the system pressure relief valve 27, the lubricating pressure relief valve 28, and the system pressure line (the line in the blue portion in FIG. 5) An unloading valve 29 is provided which is operated to protect the hydraulic circuit.

It is also possible to supply a lubricating pressure flow rate in a cooled state to the shift clutch 31 (32, 33) and the planetary gear unit 80 via the oil cooler C, 91, 92, 93, and 94, respectively, are provided on the line to supply lubricating oil with a controlled flow rate.

5, the same symbol as the oil cooler C shown in the system pressure line or the like means an oil filter.

A shift valve unit 20 for supplying oil necessary for the shift clutches 31, 32 and 33 is provided with a separate shift valve unit for supplying oil through the oil supply line 14a dedicated to the shift valve unit, The HST pump 11 is provided with a dedicated oil pump 14 and further provided with a HST (Hydrostatic Transmission) 10, through an HST exclusive oil supply line 16a A separate HST oil pump 16 for supplying oil must be provided separately.

Further, in the conventional vehicle, the steering pump 40 for supplying the oil to the steering unit 40 through the steering oil supply line 61 is provided, and when the working machine is provided, the working machine unit 100 is supplied through a working oil supply line 71. The working machine pump 71 is provided with a working machine pump 70 for supplying working oil to the work machine.

The flow rate used to flow into the steering unit 40 causes the steering cylinder 42 to operate so that the steering operation of the vehicle is performed and then discharged through the discharge line 44 and discharged through the drain line 64 And is returned to the oil tank (T).

Here, in the low engine speed region (rpm) of the vehicle, the drive force of the oil pump 14 dedicated to the shift valve portion is weak and the system such as the HST 10, the shift clutches 31, 32, 33, A system pressure line for transmitting and operating the hydraulic pressure through the proportional control valves 21 and 22 and the solenoid direction switching valves 23, 24, 25 and 26, and a system pressure line for operating the HST 10, the transmission clutch unit 30 The pressure of the lubricating pressure line which always supplies the lubricating oil to the system is lowered.

When the lubrication pressure is lowered, a problem arises in the lubrication action of the shift clutches 31, 32, 33, and adverse effects such as disk burnout of the shift clutch may be caused. Therefore, The lubricating pressure must be maintained so as to be supplied to the shift clutch.

Further, as the driving load of the vehicle is increased or the number of transmission gears is increased, the torque applied to the HST 10 is increased, so that the flow rate supplied to the HST pump 11 becomes larger, and the lubricating pressure of the transmission system pressure line and the lubricating pressure line Can be degraded. At this time, a flow rate is supplied to the HST pump 11 through the HST exclusive oil pump 16 to prevent a decrease in the lubrication pressure of the system pressure line and the lubrication pressure line.

Therefore, conventionally, an oil pump 14 dedicated to a shift valve unit for supplying oil to the shift valve unit 20, and an oil pump 14 for charging the HST pump 11 constituting the HST 10 when the HST 10 is equipped. And an HST exclusive oil pump 16 for supplying a flow rate are separately provided to overcome such a flow shortage phenomenon and maintain the lubricating pressure.

In the conventional vehicle, the oil pump 14, the steering pump 60, the working machine pump 70 and the HST exclusive oil pump 16 are all directly connected to the engine so that the engine 50 A certain amount of flow is discharged by the number of revolutions, and the more various pumps are connected, the more the engine efficiency is lowered.

In addition, since the oil pump 14 for exclusive use in the shift valve unit and the HST exclusive oil pump 16 are provided in the prior art, the structure is complicated and occupies a space, so that the vehicle can not be constructed compact, An increase in cost due to the separate provision of each oil pump has been a problem.

Korean Patent No. 10-497662 (Notification Date: July 1, 2005)

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a hydraulic system for a transmission of a vehicle such as a tractor, an oil pump dedicated to the transmission portion valve unit, A part of the flow rate supplied from the steering pump to the steering unit is branched and supplied to the system pressure line and the lubrication pressure line so that the pressure of the system pressure line and the lubrication pressure line are constant And the flow rate of the HST pump is increased due to the engine low rotation state, the driving load of the vehicle is increased or the speed of the transmission stroke is increased and the HST working pressure is increased, the flow rate The pressure of the lubricating pressure line can be maintained by supplying a flow rate to the lubricating pressure line And to provide a hydraulic system of a vehicular transmission in which a compact configuration and a cost can be saved.

In order to solve the above problems, a solving means of the present invention is a solenoid valve comprising: a shift valve unit that includes a system pressure line and a lubricating pressure line and controls the shift clutch unit to operate; A branch oil line formed on the steering oil supply line for supplying a portion of the oil of the steering oil supply line to the system pressure line; A working machine oil supply line for supplying the oil and a working machine oil branch line for supplying the working machine oil supply line with the lubricating pressure line.

It further includes a flow distribution valve for supplying a portion of the oil in the steering oil feed line to the system pressure line.

The system pressure relief valve further includes a system pressure relief valve that supplies oil to the lubrication pressure line when the pressure of the system pressure line becomes equal to or higher than a reference pressure through the oil supplied by the steering pump.

Further, the oil discharged through the discharge line of the steering unit is connected to the branch oil line.

And a pressure reducing valve for supplying oil to the lubricating pressure line on the oil branch line when the pressure of the lubricating pressure line is equal to or lower than a reference pressure.

And a relief valve for lubricating pressure on the lubricating pressure line so that the oil of the lubricating pressure line is drained through the drain line when the pressure of the lubricating pressure line becomes equal to or higher than a reference pressure.

As described above, according to the present invention, in the transmission hydraulic system of a vehicle, the shift valve unit for supplying the flow rate used for the HST operation or the oil pump for supplying the oil to the HST is not separately provided, A part of the flow rate supplied to the steering unit via the pump may be branched to supply the flow rate to the system pressure line and the lubricating pressure line so that the pressure is maintained.

Further, in the case where the absolute flow rate supplied from the steering pump in the low-speed state of the engine is insufficient, or the HST pump charge flow rate increases with an increase in the HST operating pressure due to an increase in the vehicle driving load or an increase in the speed of the transmission, When the pressure of the lubricating pressure line drops below the set pressure of the pressure reducing valve, some of the oil supplied from the working machine pump is supplied to the lubricating pressure line through the pressure reducing valve to maintain the pressure of the lubricating pressure line .

Thereby, it becomes unnecessary to provide a dedicated oil pump for supplying oil to the shift valve portion for the shift clutch operation and an HST exclusive oil pump for supplying the charge flow rate to the HST pump of the HST, and the oil piping line is also simplified, The overall hydraulic system configuration is simplified, the space is not occupied, the compact configuration is possible, and the cost required for manufacturing the vehicle can be significantly reduced.

1 is a block diagram showing a configuration of a hydraulic system of an automatic transmission for a vehicle according to an embodiment of the present invention.
2 is a hydraulic circuit diagram showing a configuration of a hydraulic system of an automatic transmission for a vehicle according to an embodiment of the present invention.
3 (a) and (b) are graphs showing the relationship between the HST charge flow rate before and after a portion of the flow rate discharged from the working machine pump is supplied to the lubricating pressure line and the amount of lubricating oil in the lubricating pressure line.
4A and 4B are graphs showing the relationship between the engine speed and the amount of lubricant before and after replenishing the working machine pump flow rate.
5 is a hydraulic circuit diagram showing a configuration of a hydraulic system of a conventional automatic transmission for a vehicle.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a block diagram showing the configuration of a hydraulic system of a vehicular transmission according to an embodiment of the present invention, and FIG. 2 is a block diagram showing the configuration of a hydraulic system of a vehicular automatic transmission according to an embodiment of the present invention. Circuit diagram.

As shown in the drawings, a hydraulic system according to an embodiment of the present invention includes an HST 10, a shift valve unit 20 and a shift clutch unit 30, and includes a steering unit A steering pump 40 and a steering pump 60 and a working machine pump 70 which are directly connected to receive power from the engine 50.

The HST 10 is basically composed of an HST pump 11 and a motor 12 as shown in FIG.

Further, the shift clutch unit 30 is provided with a forward-reverse shift clutch 31 and a forward shift clutch 32 (33).

The proportional control valves 21 and 22 and the solenoid direction changeover valves 23 and 24 for supplying the flow rate to the respective shift clutches 31, 25) 26, and includes a system pressure relief valve 27, a lubrication pressure relief valve 28, and an unloading operation which is operated to protect the hydraulic circuit when the pressure of the system pressure line rises above the set reference pressure A valve 29 is further provided.

According to an embodiment of the present invention, the steering pump 60 supplies the steering unit 40 with a predetermined flow rate through the flow distributing valve 62 to operate the steering cylinder 40, (Not shown), and is supplied through a system pressure line (line indicated by blue in FIG. 2) to be supplied to the transmission valve unit 20 ).

More specifically, according to an embodiment of the present invention, oil is supplied to the steering unit 40 by operation of the steering pump 60, which is directly connected to the engine 50 and is operated in accordance with the driving of the engine 50 And a flow distributing valve 62 is provided on the steering oil supply line 61. [

Here, the oil flow rate is supplied to the steering unit 40 via the flow distributing valve 62 and is connected to the system pressure line through the branch oil line 63 branched from the steering oil supply line 61, Oil is supplied to the system pressure line to create line pressure.

In Fig. 2, the branch oil line 63 is a line connected to the system pressure line, which will be described in blue for convenience of description of the present invention.

As the flow rate of the flow into the steering unit 40 is rotated left and right by a handle (not shown), the flow of the flow of the steering valve spool to the steering cylinder 42 connected to the front wheel is controlled to control the steering direction of the vehicle do.

The flow rate that is used to flow into the steering unit 40 is recovered again and discharged through the discharge line 44 at which the branch oil line 63 joins the branch oil line 63 and enters the system pressure line.

Further, according to the embodiment of the present invention, a system pressure relief valve 27 is provided on the system pressure line, and a portion of the oil supplied from the steering pump 60 through the branch oil line 63 is branched And the reference pressure required for the system pressure line is formed through the discharge line 44 of the steering unit 40, the system pressure relief valve 27 is operated so that a part of the flow rate of the system pressure line And branches to a lubricating pressure line (line marked yellow in Fig. 2).

The flow rate branched to the lubricating pressure line through the system pressure relief valve 27 is supplied to the shift clutch 31, 32, 33 and the planetary gear 80 in a cooled state through the oil cooler C 32 and 33 and the planetary gear 80 to prevent damage due to the shortage of the oil flow rate.

When the reference pressure is formed through the oil supply to the lubricating pressure line, the remaining oil flows through the relief valve 28 for lubricating pressure located on the lubricating pressure line to the drain line (the line indicated by green in Fig. 2) 64, drained to the oil tank T, and recovered.

According to one embodiment of the present invention, the system oil pressure flow rate formed in the system pressure line is transmitted through the solenoid direction changeover valves 23, 24, 25, 26 and the proportional control valves 21, 31) 32, 33 and supplies the charge flow rate to the HST pump 11 for the operation of the HST 10.

The proportional control valves 21 and 22 connected to the shift clutch 31 are connected to solenoidal directional control valves 23 and 24 that are engaged with the forward shift clutches 32 and 33 24, 25, and 26 are provided for driving and operating in the first, third, second, and fourth stages, respectively.

In other words, for example, if the user sets the forward shift lever to the forward position and sets the drive shift lever to the predetermined speed, after the operation of the forward and reverse operation shift clutch 31, the shift clutch 32 The solenoid direction switching valve 23, 24, 25 and 26 for solenoid direction switching valve 23, solenoid direction switching valve 25, solenoid direction switching valve 24, And the solenoid direction switching valve 26 in this order to operate the shift clutches 32, 33,

Only one solenoid direction switching valve is in the ON state and the remaining three solenoid direction switching valves are in the OFF state in accordance with the respective speed ranges of the traveling speed change clutches 32 and 33. [

The forward and backward proportional control valves 21 and 22 are in a state in which one of the forward and backward operations is in operation. By controlling the operation of the forward / reverse shift clutch 31 in the forward shift and the reverse shift, Can be reduced.

In the traveling transmission portion, since there is no speed difference between the speed change points for the respective speed change stepwise gear shift shocks, no solenoid direction changeover valves 23, 24, 25 and 26 are provided for use .

The lubrication pressure flow rate formed in the lubrication line is controlled by the orifices 91, 92, 93 and 94 provided on the lubricating lines of the respective shift clutches 31, 32, 33 and the planetary gear unit 80 ≪ / RTI >

In other words, the orifices 91, 92, 93, and 94 having different diameters are required because the lubricating pressure flow rates required for the respective shift clutches 31, 32, 33 and the planetary gear unit 80 are different, So that the flow rate is adjusted appropriately.

According to an embodiment of the present invention, when the engine 50 of the vehicle is in a low rotational speed (rpm) state, the steering pump 60 directly connected to the engine 50 is also reduced in proportion to the oil discharge amount The absolute flow rate supplied through the steering pump 60 becomes insufficient. Since the deficient flow rate is supplied to the system pressure line in the most of the flow rate, the flow rate supplied to the lubricating pressure line becomes small.

Further, when the operating load of the HST 10 is increased due to an increase in the driving load or the number of transmission stages of the vehicle, the flow rate of charge to the HST pump 11 is increased to temporarily increase the flow rate supplied to the system pressure line, The flow rate of the lubricating oil supplied through the lubricating pressure line 27 to the lubricating pressure line is reduced and the pressure of the lubricating pressure line is not constant.

In this case, when the flow rate discharged from the working machine pump 70 is supplied to the working machine unit 100 through the working machine oil supply line 71 (pink arrow direction in Fig. 2), a part of the flow rate is branched, The oil can be supplemented to the lubricating pressure line through the branch line 72.

In other words, since the pressure reducing valve 90 is provided on the working oil branch line 72, when the pressure of the lubricating pressure line drops below the reference pressure set by the pressure reducing valve 90 (that is, (10) a flow rate shortage phenomenon due to an increase in flow rate of charge to the HST pump 11 due to an increase in operating pressure), the pressure reducing valve 90 is operated The flow rate is supplied to the lubricating pressure line to lower the pressure of the lubricating pressure line to prevent the transmission clutches 31, 32, 33 and the planetary gear 80 from being damaged.

On the other hand, when the pressure of the lubricating pressure line is formed to the reference pressure, the pressure reducing valve 90 is not operated, and therefore the flow rate discharged from the working machine pump 70 is all supplied to the working machine unit 100.

The reference pressure described above may have various values depending on the configuration of the hydraulic circuit.

3 is a graph showing the relationship between the HST charge flow rate before and after a portion of the flow rate discharged from the working machine pump 70 is supplied to the lubricating pressure line and the amount of lubricating oil in the lubricating pressure line, 70 does not supply a flow rate to the lubricating pressure line, it can be confirmed that the amount of lubricating oil in the lubricating pressure line decreases as the HST charge flow rate increases. FIG. 3 (b) 70) is supplied to the lubricating pressure line, the amount of lubricating oil in the lubricating pressure line is kept constant even if the HST charge flow rate is increased.

4 is a graph showing the relationship between the engine speed and the amount of lubricating oil in the lubricating pressure line before and after supplying the working machine pump flow rate to the lubricating pressure line. Fig. 4 (a) FIG. 4 (b) shows a state in which the amount of lubricating oil in the lubricating pressure line is reduced when the number of revolutions of the engine is in the low engine speed region (the region to the point A) When the flow rate of the working machine pump 70 is supplied to the lubrication pressure line according to the embodiment, the lubrication pressure is kept constant even in the engine revolution number region (the region up to the point A).

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, But fall within the scope of the appended claims.

10: HST
11: HST pump
12: Motor
14: Oil pump for shift valve only
14a: Oil supply line dedicated to the shift valve portion
16: Oil pump for HST only
16a: HST exclusive oil supply line
20:
21, 22: Proportional control valve
23, 24, 25, 26: solenoid direction switching valve
27: Relief valve for system pressure
28: Relief valve for lubricating pressure
29: Unloading valve
30: Transmission clutch unit
31, 32, 33: Transmission clutch
40: Steering unit
42: Steering cylinder
44: discharge line
50: engine
60: Steering pump
61: Steering oil supply line
62: Flow distribution valve
63: Branch oil line
64: drain line
70: Machine pump
71: Machine oil supply line
72: Machine oil branch line
80: Planetary fisherman
90: Pressure reducing valve
91, 92, 93, 94: Orifice
100:
A: Branch
C: Oil cooler
P: junction point
T: Oil tank

Claims (6)

A shift valve unit 20 provided with a system pressure line and a lubricating pressure line and controlling the shift clutch unit 30 to be operated;
A steering oil supply line 61 for supplying oil from the steering pump 60 to the steering unit 40;
A branch oil line 63 formed on the steering oil supply line 61 to supply a portion of the oil of the steering oil supply line 61 to the system pressure line;
A working machine oil supply line 71 for supplying the working machine unit 100 with oil from the working machine pump 70;
A working machine oil branch line (72) for supplying the working machine oil supply line (71) with the lubricating pressure line;
And the hydraulic system of the vehicle.
The method according to claim 1,
Further comprising a flow distributing valve (62) for supplying a portion of the oil of the steering oil supply line (61) to the system pressure line.
The method according to claim 1,
Further comprising a system pressure relief valve (27) for supplying oil to the lubrication pressure line when the pressure of the system pressure line exceeds the reference pressure through the oil supplied by the steering pump (60) Hydraulic system of a transmission for a vehicle.
The method according to claim 1,
And the oil discharged through the discharge line (44) of the steering unit (40) is connected to the branch oil line (63).
The method according to claim 1,
And a pressure reducing valve (90) on the oil branch line (72) for supplying oil to the lubricating pressure line when the pressure of the lubricating pressure line is lower than a reference pressure.
The method according to claim 1 or 5,
And a relief valve (28) for lubricating pressure on the lubricating pressure line so that the oil of the lubricating pressure line is drained through the drain line (64) when the pressure of the lubricating pressure line becomes equal to or higher than a reference pressure The hydraulic system of the vehicle transmission.

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