JPH078658B2 - Break structure of tractor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Field of Industrial Application The present invention relates to the supply of hydraulic oil when the left and right steering brake devices of a tractor are hydraulically operated.

(B) Conventional Technology In the related art, in a brake device for simultaneously braking left and right wheels like an automobile, a technique for arranging a hydraulically operated traveling brake device has been known. For example, it is like the technique described in JP-A-59-130774.

Also, in a tractor as well, a steering brake device that applies braking separately to the left and right wheels to perform steering is a hydraulically operated brake device, and a technology such as Japanese Utility Model Laid-Open No. 50-6027 is known. It is said that.

(C) Problems to be Solved by the Invention An object of the present invention is to provide a conventional hydraulically operated steering brake device in which a tank for hydraulic oil is provided separately, and a brake valve for the steering brake device is provided from the hydraulic oil tank. It was supplying hydraulic oil to the brake piston.

However, when the amount of hydraulic oil in the hydraulic oil tank decreases,
There is a problem that the brake does not work and safety is deteriorated, and piping from the hydraulic oil tank to the brake valve is required.

Further, there is a risk that air is often trapped between the hydraulic oil tank and the brake device, and the steering brake device is not braked by the air trapping.

The present invention solves these conventional problems.

(D) Means for Solving the Problems The object of the present invention is as described above, and a configuration for achieving the object will be described below.

In the configuration in which the hydraulic clutch device is arranged inside the mission case 12, the center plate 1 is sandwiched between the front and rear joint surfaces of the mission case 12, and the hydraulic case 8 of the hydraulic brake device is fixed to the side of the center plate 1. The low-pressure oil discharged from the hydraulic device for connecting and disconnecting the hydraulic clutch device is introduced from the center plate 1 through the inflow hole 8e into the hydraulic oil tank 8a formed in the hydraulic case 8 to generate the hydraulic oil. An overflow hole 8d is formed in the upper part of the tank 8a, and when the hydraulic oil is supplied to the hydraulic oil tank 8a in a certain amount or more, the excess hydraulic oil is returned from the overflow hole 8d to the mission case 12. It is a thing.

Further, an air vent bolt 19 for venting the air in the hydraulic oil tank 8a is screwed into the hole communicating with the overflow hole 8d.

(E) Embodiments The object and structure of the present invention are as described above. Next, the structure and operation of the embodiment shown in the accompanying drawings will be described.

FIG. 1 is a side view showing a brake structure of a tractor of the present invention, FIG. 2 is a plan view of the same, FIG. 3 is a side sectional view of the inside of a transmission case of the tractor, and FIG. 4 is a side view of a hydraulic device for a steering brake. 5 and 5 are also plan views, FIG. 6 is a cross-sectional view of a spacer 18, FIG. 7 is a side sectional view, FIG. 8 is a rear sectional view, and FIG. 9 is a plan sectional view.
FIG. 10 is a side sectional view of the inertial idle braking device, FIG. 11 is a rear view of the same, and FIG. 12 is a hydraulic circuit diagram of the tractor of the present invention.

1 and 2 will be described.

A clutch housing 11 is fixedly provided on the rear surface of the engine arranged in the hood of the tractor, and between the rear surface of the clutch housing 11 and the mission case 12,
The center plate 1 of the present invention is sandwiched. A rear axle case 13 is fixed to the rear surface of the mission case 12. Steering brake devices 40L, 40R are arranged on the side surface of the rear axle case 13.

The spacer 18 and the hydraulic case 8 constituting the hydraulic device of the steering brake devices 40L and 40R of the present invention are fixedly provided on the right side surface of the center plate 1 described above.

Inside the hydraulic case 8, a hydraulic oil tank 8a, brake valves 6L, 6R, brake pistons 4L, 4R, etc. are configured. Then, the front ends of the left and right brake pistons 4L, 4R are pushed by the pressing pieces 2a of the brake pedals 2L, 2R, and the pressure oil is sent to the steering brake devices 40L, 40R via the pipings 3L, 3R.

Next, the clutch housing 11 and the transmission case 1 shown in FIG.
2, based on the side sectional view of the rear axle case 13 part,
The power transmission system will be described.

The main clutch device arranged in the clutch housing 11 is configured as a dual clutch, and the engine rotation is divided into both the travel input shaft 21 and the PTO input shaft 22 so that the power can be connected / disconnected.

The rotation of the traveling input shaft 21 is transmitted to the gears on the forward drive shaft 24 and the reverse drive shaft 25 via the loosely fitted gears on the drive shaft 23, and the gears on the forward drive shaft 24 and the reverse drive shaft 25 and the shaft 23 are transmitted. By meshing with the upper gear, a transmission M having three forward gears and one reverse gear is configured.

Then, directly connect the rear end of the shaft 23 and the front and rear of the shaft 30, or
The ultra-low speed transmission H is configured depending on whether to bypass the ultra-reduction gear train.

Further, power is transmitted from the shaft 30 to the shaft 31, and between the gear on the shaft 31 and the gear on the pinion shaft 28, a high / middle / low three-stage auxiliary transmission S is constructed.

Next, the PTO power transmission system from the PTO input shaft 22 will be described.

The power of the PTO input shaft 22 is transmitted to the shaft 26 via the loose fitting gear on the shaft 23.
It is transmitted to the upper hydraulic clutch device A. The PTO rotation is turned on and off by connecting and disconnecting the hydraulic clutch device A.

The rotation after the connection and disconnection is transmitted to the gear on the PTO speed change shaft 26 by the hydraulic clutch device A, and the rotation of the gear on the PTO speed change shaft 26 and the PTO
The four-stage PTO transmission N is constructed between the gears on the shaft 27.

Further, power is taken out from a gear provided at the front end of the pinion shaft 28, and the front wheel drive shaft 32 is driven by a gear loosely fitted to the PTO shaft 27.

Further, an inertial slip prevention brake device B for preventing inertial slippage of the PTO shaft 27 is arranged at the rear end of the PTO speed change shaft 26. The inertia slip prevention brake device B is a gear sliding type PT.
The O transmission N is configured to be released during a gear shift operation so that the gear shift operation can be performed smoothly.

Next, the hydraulically operated brake structure of the present invention will be described with reference to FIGS. 4 to 9.

A spacer 18 is provided on an exposed portion outside the side wall of the center plate 1 sandwiched between the mission case 12 and the rear axle case 13.
That is, the hydraulic case 8 is fixedly installed. The hydraulic case 8 also serves as the hydraulic oil tank 8a, the valve case of the brake valve 6 and the cylinders of the brake pistons 4L and 4R, and in addition, constitutes the pivotal support body of the brake pedals 2L and 2R. Of.

That is, the pivot 8b of the pivot shaft 20 is projected from the hydraulic case 8, and the pivot 20 is provided on the pivot 8b to separately pivot the left and right brake pedals 2L, 2R. .

A pressing piece 2a is provided below the brake pedals 2L and 2R, and the pressing piece 2a is covered by the bellows 9 when the brake pedals 2L and 2R are depressed.
The L and 4R are pushed against the biasing spring 5.

A hydraulic oil tank 8a is formed in the upper part of the hydraulic case 8, and the hydraulic oil tank 8a has a low pressure relief valve shown in FIG.
Inflow hole 8e for the pressure oil that has been subjected to low pressure by 42 to flow in
Is opened, and from the oil passage 1a of the center plate 1 through the oil passage of the spacer 18 to the hydraulic clutch device A.
That is, the discharge oil of the operating oil is reduced in pressure and sent. When a certain amount or more of hydraulic oil is sent from the inflow hole 8e,
From the overflow hole 8d through the overflow hole 1b of the center plate 1,
It is configured to flow back into the mission case 12.

Further, as shown in FIG. 6, an air vent bolt 19 is arranged in the overflow hole 1b portion of the spacer 18. Therefore, when air is trapped in the hydraulic oil tank 8a, it can be removed by the air release bolt 19.

A valve seat 14 is screwed on the lower portion of the hydraulic oil tank 8a, and the valve seat 14 is spring-biased so that the brake valve 6 can be opened and closed. Normally, when the brake pedals 2L, 2R are not depressed, the brake valve 6 is locked by the engaging grooves of the brake pistons 4L, 4R and inclined as shown in FIG. 7, and is in the open state. Of. In the open state, the hydraulic oil in the hydraulic oil tank 8a is flowing into the cylinder chambers of the brake pistons 4L and 4R.

When the brake pedals 2L and 2R are depressed from this state, the engagement state between the engagement grooves of the brake pistons 4L and 4R and the brake valve is released, and the brake valve 6 is biased by the spring to close the opening of the valve seat 14. However, the hydraulic oil in the cylinder chamber is prevented from returning to the hydraulic oil tank 8a.
By further depressing the brake pedals 2L, 2R, pressure oil is transferred from the piping 3 to the steering brake devices 40L, 40R.
It is discharged toward.

Reference numeral 16 is a limiting pin that limits the amount of depression of the brake pistons 4L and 4R.

Further, at the bottom of the brake pistons 4L, 4R, equalizer valves 7L, 7R are provided for the left and right brake pistons 4L, 4R respectively. The equalizer valves 7L, 7R are only one when the brake pedal 2 on the left or right is depressed. Although it does not open because it does not open, when the left and right brake pedals 2L and 2R are simultaneously depressed, the left and right equalizer valves 7L and 7R are opened at the same time, and the left and right brake pistons 4L and 4R are discharged. The pressure of the pressure oil is exactly the same, and the braking forces of the steering braking devices 40L and 40R are made the same, thereby eliminating the one-sided effect of the brake during high-speed traveling.

The pressure oil that is pressurized and discharged by the brake pistons 4L and 4R is inherited from the joint 15 to the piping 3,
The steering brake devices 40L and 40R.

Next, referring to FIGS. 10 and 11, inertial slip prevention brake device B
The configuration of will be described.

The rear end of the PTO transmission shaft 26 is fitted in the wall of the transmission case that constitutes the brake case 12a. A braking piston 34 is fitted in the brake case 12a, and when the hydraulic clutch device A is in a connected state, the braking piston 34 is supplied with pressure oil also to the cylinder portion of the braking piston 34. The braking piston 3 is pushed out against the braking spring 36 to the extent that it abuts the stopper plate 33, the braking friction plate 35 is released, and the PTO integrated with the braking friction plate 35 is released. The speed change shaft 26 can freely rotate without being subjected to braking.

However, conversely, when the pressure oil that is in the connected state of the hydraulic clutch device A is released to the drain oil passage, the braking piston 34 is pushed back by the braking spring 36, and the braking piston 34 causes the braking friction plate 38 to contact the braking case 12a. The braking force is applied to the rotation of the PTO speed-change shaft 26 by pressing the braking friction plate 35 while pressing the braking friction plate 35.

Next, the hydraulic circuit diagram of FIG. 12 will be described. In this tractor, three sets of hydraulic pumps 39, 38 and 37 are arranged and driven by the power of the engine.

The hydraulic pump 39 is a hydraulic pump for the power steering device T, and the hydraulic pump 3 is a hydraulic pump for the working device lifting hydraulic device U mounted on the tractor. The hydraulic pump 37 is a hydraulic pump for sending hydraulic clutch device A and operating oil for operating the steering brake device. In the hydraulic circuit from the hydraulic pump 37, 41 is a high pressure relief valve and 42 is a low pressure relief valve. In the present invention, what is introduced into the hydraulic oil tank 8a in the hydraulic case 8 is low-pressure drain oil when the hydraulic control valve 44 is switched by the PTO clutch lever 43 to disconnect the hydraulic clutch device A. The low-pressure oil is also used to lubricate the hydraulic clutch device A from the PTO transmission shaft 26.

As a result, in the conventional hydraulically operated brake device for the tractor, the hydraulic oil tank was provided separately from the mission case, so there was a problem that the brake did not work when the hydraulic oil decreased due to natural decrease. However, by using the lubricating oil in the mission case and the rear axle case as hydraulic oil as in the present invention,
Since sufficient hydraulic oil can be secured, the danger due to natural reduction can be avoided.

Further, there is also a technique in which the pressure oil for raising and lowering the working machine is used by guiding it to the working tank in the conventional technique, but in this case, the hydraulic device for raising and lowering the working machine and the working oil tank 8a for the brake device are used. There was a problem that it was necessary to provide piping and oil passages because the spaces were separated. In the present invention, by introducing the hydraulic oil from the center plate 1, it is possible to eliminate the problems of these points.

Further, by fixing the hydraulic case 8 to the center plate 1, the hydraulic case 8 is firmly supported, and the hydraulic case 8 itself can be used as a support for the brake pedals 2L, 2R. is there. Therefore, it is not necessary to separately provide the support for the brake pedals 2L and 2R and the hydraulic case 8 as in the conventional case.

(F) Effects of the Invention Since the present invention is configured as described above, it has the following effects.

First, by attaching the hydraulic case 8 to the side of the center plate 1, it is not necessary to provide a processed portion for attaching the hydraulic case 8 to the mission case 12, and the mission case is provided with a hydraulic clutch device. 12 and
Mission case without hydraulic clutch device
It is possible to use 12 as a part that is also used.

Secondly, the oil passage is complicatedly bored, and the hydraulic case 8 which is a complicated hydraulic component is attached only to the center plate 1 to which the hydraulic pump, the seal case, etc. are attached, thereby centralizing the hydraulic components. It is possible to concentrate a portion having a high degree of processing only on the center plate 1.

Thirdly, since the spacer 18 formed inside the hydraulic case 8 is provided with the two inflow holes 8e on the lower side and the overflow holes 8d on the upper side, hydraulic oil is supplied to the inflow hole 8e more than necessary. It is now possible to secure the necessary amount of brake fluid.

Fourthly, since the air vent bolt 19 is provided in the hole communicating with the overflow hole 8d of the hydraulic oil tank 8a, air can be easily vented, so that the piping 3 and the steering brake device are provided.
It was possible to reduce the number of accidents in which air was trapped in the 40L and 40R cylinders and braking was not effective.

[Brief description of drawings]

FIG. 1 is a side view showing a brake structure of a tractor of the present invention, FIG. 2 is a plan view of the same, FIG. 3 is a side sectional view of the inside of a transmission case of the tractor, and FIG. 4 is a side view of a hydraulic device for a steering brake. 5 and 5 are plan views of the same, FIG. 6 is a partial sectional view of the spacer 18, and FIG. 7 is a side sectional view of the same.
The same figure shows a rear sectional view, and FIG. 9 shows a plan sectional view.
FIG. 10 is a side sectional view of the inertial idler brake device, FIG. 11 is a rear view of the same, and FIG. 12 is a hydraulic circuit diagram of the tractor of the present invention. A: Hydraulic clutch device B: Inertial inertia prevention brake device 1 ... Center plate 2 ... Brake pedal 3 ... Piping 4 ... Brake piston 5 ... Bias spring 6 ... Brake valve 8 ... Hydraulic case 8a …… Hydraulic oil tank 18 …… Spacer

Claims (2)

[Claims] 1. A hydraulic clutch device is disposed inside a mission case 12, a center plate 1 is sandwiched between front and rear joint surfaces of the mission case 12, and a hydraulic case 8 of a hydraulic brake device is provided on the side of the center plate 1. In a fixed construction, a low-pressure oil discharged from the hydraulic device for connecting and disconnecting the hydraulic clutch device is arranged in the hydraulic case 8 from the inside of the center plate 1 through the inflow hole 8e.
8a, the overflow hole 8d is formed in the upper portion of the hydraulic oil tank 8a, and when the hydraulic oil is supplied to the hydraulic oil tank 8a in a certain amount or more, the excess hydraulic oil is transmitted from the overflow hole 8d. A tractor brake structure characterized by being configured to return to the case 12. 2. A brake for a tractor, characterized in that an air vent bolt (19) for venting air in the hydraulic oil tank (8a) is screwed into a hole communicating with the overflow hole (8d) according to claim 1. Construction.