JP2001193774A - Wet brake - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the construction of a cooling oil circuit for reducing a pressure load on a seal and extend the life of the seal while considering that a pressure load on a cooling oil, which exert a great influence on the life of the seal such as an oil seal or a face seal, is desirably reduced for long service of the seal. SOLUTION: A wet brake comprises a relief flow passage 1 provided in either an inner gear shaft 2 or a seal housing 3 constituting a flow passage for a brake cooling oil circuit right before a seal 4, depending on a difference in cooling oil flow direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to adjustment of seal pressure in a cooling oil circuit of a wet brake.

[0002]

2. Description of the Related Art Conventionally, in a wet brake employing a forced cooling system, pressure is applied to cooling oil in order to circulate brake cooling oil in a cooling oil circuit, and a seal capable of withstanding this pressure is applied. Was used.

[0003]

However, since the pressure applied to the cooling oil has a great effect on the life of seals such as oil seals and face seals, it is desirable that a small pressure be used for the life of the seal. Met.
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a configuration of a cooling oil circuit for reducing a pressure applied to a seal, and to prolong the life of the seal.

[0004]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and has a flow path of a brake cooling oil circuit immediately before a seal in accordance with a difference in a flow direction of cooling oil. The relief brake is provided in one of the inner gear shaft and the seal housing.

When the cooling oil circuit is constructed as described above, the pressure of the cooling oil applied to the seal is reduced by the action of the relief flow passage until it approaches the pressure in the return circuit. The life of the face seal and the like becomes longer.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described.
This will be described with reference to the drawings. FIG. 1 is a cross-sectional view of a first embodiment of a wet brake having a relief flow passage provided on an inner gear shaft according to the present invention, and FIG. 2 is a cross-sectional view of a second embodiment having a relief flow passage provided on a seal housing. .

In FIG. 1, the cooling oil flows from the pump 8 in the direction indicated by the arrow through the flow path of the outer gear housing 7 and passes through the gap between the friction surfaces of the multi-plate brake sandwiched between the piston 5 and the seal housing 3. .

The cooling oil that has passed through the multi-disc brake divides the outer portion of the rotating inner gear shaft 2 into the piston 5 and the seal housing 3, and the cooling oil on the seal housing 3 is formed by the seal 4. A hole 11 provided toward the inside of the inner gear shaft 2 flows from the space portion to the return circuit 1 provided in the cylinder 6 through the hole 11 serving as the relief flow path 1. The cooling oil on the piston 5 side flows to the return circuit of the cylinder 6 as it is.

[0009] Hydraulic pressure in front of the multi-plate brake in the flow circuit of the cooling oil, maintains the discharge pressure P ₁ of the pump 8, the seal 4 just before the space drops of pressure through the multi-disc brake cooling oil pressure P ₂ of has a pressure approximately equal to the cooling oil pressure P ₃ in the return circuit. That is, P ₁
> P ₂ ≒ P ₃ .

[0010] In the case of the conventional structure the relief flow path 1 is not provided, the cooling oil pressure P ₂ in the seal 4 just before the space, with respect to the cooling oil pressure P ₃ in the return circuit, yet The pressure required to pass through the meshing of the gear portion with the multiple plates is required, and P ₂ > P ₃ must be maintained. The oil pressure applied to the seal 4 is as shown in FIG. 1 showing the first embodiment. It is higher than the case.

In the second embodiment shown in FIG. 2 in which the flow direction of the cooling oil flows from the inner gear shaft 2 side to the outside, opposite to that in FIG. 1, the relief passage 1 presses the friction plate of the seal housing 3. Although a groove 12 is provided in the seal housing 3, a through hole may be provided if the seal housing 3 has a sufficient dimension in the axial direction. Pressure distribution of each portion in this second embodiment is basically the same as in the first embodiment of FIG. 1, which consists the relationship _{P 1> P 2 ≒ P 3} .

As described above, the resistance when the cooling oil filling the space immediately before the seal 4 flows into the return circuit is reduced by providing the relief flow path 1 so that the seal 4 , The pressure of the cooling oil applied to the oil seal and the pressure in the return circuit are reduced until the pressure approaches the pressure in the return circuit, and the life of the oil seal, face seal, and the like can be extended.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a first embodiment of a wet brake in which a relief passage according to the present invention is provided on an inner gear shaft.

FIG. 2 is a sectional view of a second embodiment of a wet brake provided with a relief flow passage in a seal housing according to the present invention.

FIG. 3 is a cross-sectional view of a conventional wet brake having no relief channel.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Relief flow path 2 Inner gear shaft 3 Seal housing 4 Seal

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3F333 AA20 AB20 FH08 FH10 3J043 AA15 BA05 CA02 CB13 3J058 AA44 AA48 AA53 AA59 AA70 AA77 AA83 AA87 BA25 CD03 DE03

Claims (1)

[Claims] In a wet type brake employing a forced cooling system, an inner gear shaft (2) constituting a flow path of a brake cooling oil circuit immediately before a seal (4) is provided in accordance with a difference in a flow direction of cooling oil. ) Or a seal housing (3), wherein a relief flow path (1) is provided.