JPS6154891B2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a three-pump hydraulic system for a backhoe equipped with a soil removal plate.

[Prior art and problems]

In the conventional two-pump bucket hoe, among the combined operations of the bucket hoe, the most frequently performed operations are the bucketing operation (excavation operation) while moving the arm of the bucket hoe, and the turning operation (loading operation) while moving the boom. These are hereinafter referred to as basic compound operations). Conventionally, the two-pump type bucket hoe uses two pumps to drive the cylinders of the bucket, arm, boom, and earth removal plate, as well as the motors of the swing and traveling crawlers (left and right). , the first pump is connected in parallel to the arm switching valve, swing switching valve, and running switching valve (left), while the second pump is connected to the boom switching valve, bucket switching valve, earth removal plate switching valve, and running switching valve ( right) in parallel,
The first pump is configured to handle the arm cylinder, swing motor, and traveling motor (left), and the second pump is configured to handle the boom, bucket, and earth removal plate cylinders, and the traveling motor (right). That is, with the above configuration, when performing the basic compound operation, it is sufficient to perform one operation with each of the first and second pumps. Therefore, in the case of an excavation operation in the compound operation, the oil of the first pump is transferred to the arm cylinder, the oil of the second pump is transferred to the bucket cylinder, and in the case of a loading operation, the oil of the first pump is transferred to the arm cylinder. The entire amount of oil from the second pump can be supplied to the swing motor, and the oil from the second pump can be supplied to the boom cylinder, making it possible to speed up and smoothly perform each of the above basic complex operations (the speed at which each of the above operations is performed depends on the speed of the pump). (The faster the amount of oil supplied, the faster) Generally, one operating lever can switch two switching valves, and up to two switching valves within the same pump can be switched, allowing two operations within the same pump. However, in the above configuration, two operations within the same pump, namely [arm drive +
When performing [swinging], [boom drive + bucket drive], and [traveling + ejecting plate drive], the two operation circuits are parallel circuits for one pump, so of the two operations, The disadvantage is that oil flows preferentially to operations with lower pressure, and the speed at which the amount of oil decreases is slowed down, making it impossible to perform complex operations smoothly. Furthermore, even if the pump oil were to flow equally for the two operations, the speed of the two operations would be reduced compared to when the entire amount of oil from one pump was supplied to one operation. In particular, when performing a combined operation of [traveling + earth removal plate drive], the entire amount of oil from the first pump is supplied to the left travel motor, while the second pump's oil is supplied to the right travel motor and the earth removal plate. Because of the power supplied to the cylinder, the speed of the right travel motor was slower than that of the left travel motor, making it impossible for the backhoe to travel straight. In this way, in the case of a two-pump bucket hoe, the above two operations within the same pump, namely [swing + arm drive], [bucket drive + boom drive] and [traveling + earth removal plate drive], are not possible, and furthermore, these two operations cannot be performed in the same pump. It was also impossible to perform 3 or 4 movements, which were combinations of compound movements. A three-pump type backhoe has also been proposed to solve the problem of straight running in the combined operation of [traveling + earth removal plate drive]. In the conventional three-pump bucket hoe, the first
The arm switching valve, swing switching valve, and running switching valve (left) are connected in parallel to the pump, while the bucket switching valve, boom switching valve, and running switching valve (right) are connected in parallel to the second pump, and the third pump is connected in parallel to the bucket switching valve, boom switching valve, and running switching valve (right). The soil discharge plate switching valve is configured to be connected to the pump independently. Therefore, when performing a combined operation of [traveling + earth removal plate drive], oil from the first pump is sent to the left traveling motor, oil from the second pump is sent to the right traveling motor, and oil from the third pump is sent to the left traveling motor. The entire amount can be supplied to each earth removal plate,
It is possible to drive straight even while operating the earth removal plate. However, even with this configuration, the first
The combined operation of two operations in the pump or the second pump, namely [swivel + arm drive] and [bucket drive + boom drive], cannot be performed as quickly and smoothly as in the above-mentioned two-pump bucket hoe; Furthermore, the third and fourth movements could not be performed smoothly. Moreover, the third pump was used exclusively for driving the earth removal plate, and was completely useless as it simply ran idly for purposes other than earth removal work. A hydraulic system that is an improved three-pump type is known as a solution to this problem. This hydraulic system basically handles the swing, bucket, boom, and travel (left) with the first pump, the arm, travel (right) with the second pump, and the soil removal plate with the third pump. At times other than earth removal work, the third pump is configured to join the boom. According to this hydraulic system, two pumps in the first pump
When performing two operations (swing + boom drive), for example, even if the oil from the first pump flows preferentially to the swing motor with lower pressure, the oil from the third pump can be supplied to the boom, so the boom The operating speed of is not reduced. Therefore, the two operations within the first pump, ie, the [swinging + boom driving] operations can be performed smoothly. Therefore, if you perform arm operation with the second pump [swivel + boom drive + arm drive]
These three operations can be performed smoothly. Similarly, [boom drive + bucket drive], [boom drive + bucket drive +
Arm drive] 2nd and 3rd movements can be performed smoothly. However, the combined operation of [swivel + bucket drive] within the first pump slows down the operation speed and cannot be performed smoothly for the reasons mentioned above. For this reason, [swivel + bucket drive + boom drive], [swivel + bucket drive + arm drive] and [swivel +
The third and fourth operations (bucket drive + boom drive + arm drive) could not be performed smoothly. In general, in Batsukuho equipped with earth removal plates,
Along with the combined operation of [traveling + earth removal plate drive], turning,
It is desirable to be able to smoothly perform 2nd, 3rd, and 4th movements of all combinations of the arm, boom, and bucket.

【the purpose】

The present invention was developed to improve the shortcomings of the conventional two-pump and three-pump systems described above, and by supplying pressure oil from the third pump only to the boom switching valve, all of the various complex operations described above can be performed. It provides a three-pump hydraulic system for backhoes that can be operated smoothly.

【composition】

A three-pump hydraulic system according to the present invention for achieving the above object has a swing switching valve and a left travel switching valve connected in parallel to the first pump, a bucket switching valve connected in parallel to the swing motor, and a first pump connected in parallel with a bucket switching valve. Connect the arm switching valve, boom switching valve, and right travel switching valve to the 2nd pump in parallel, and connect the soil removal plate switching valve to the 3rd pump. It is configured to flow only into the boom switching valve via the earth removal plate switching valve. Therefore, the hydraulic pressure of the three pumps is supplied without being affected by the balance of loads applied to each actuator except the earth removal plate cylinder.

【Example】

An embodiment according to the present invention will be described in detail below with reference to the drawings. As shown in FIGS. 1 and 2, the backhoe has a swivel base 2 installed on a crawler-type traveling vehicle body 1 so as to be able to drive the full range of rotation.
A driver's seat 4 is provided, and a bucket hoe device 8 consisting of a bucket 5, an arm 6, and a boom 7 is attached in front of the driver's seat. On the other hand, an earth removal plate 9 is attached to the crawler type traveling vehicle body 1. The bucket 5, the arm 6, the boom 7, and the earth removal plate 9 rotate around their fulcrums by the expansion and contraction of the bucket cylinder 10, arm cylinder 11, boom cylinder 12, and earth removal plate cylinder 13, respectively.
The rotating platform 2 is rotated by a rotating motor 14, while the crawler type traveling vehicle body 1 is rotated by left and right traveling motors 15,
15'. Bucket cylinder 10, arm cylinder 11,
Boom cylinder 12, earth removal plate cylinder 13, swing motor 14, and left and right travel motors 15, 1
5' is driven by three hydraulic pumps 16, 17, and 18, each of which is driven by an engine, and the driving and stopping of each cylinder and motor are provided between the cylinders and motors and the hydraulic pumps, as shown in FIG. The bucket switching valve 19, the arm switching valve 20, the boom switching valve 21, the earth removal plate switching valve 22, the swing switching valve 23, the left running switching valve 24, and the right running switching valve 25 are controlled respectively. . The three-pump hydraulic system according to the present invention shown in FIG.
A bucket switching valve 19 is connected in series to the second pump 17, an arm switching valve 20, a boom switching valve 21, and a right travel switching valve 25 are connected in parallel to the second pump 17, and a soil removal plate is connected to the third pump 18. Connect the switching valve 22,
When working on anything other than the earth removal plate 9, the third pump 18 is configured to flow into the boom switching valve 21 via the earth removal plate switching valve 22. Further, the bucketed cylinder 10 is connected to the bucketed switching valve 19, and the arm cylinder 11 is connected to the arm switching valve 20.
However, if the boom cylinder 12 is connected to the boom switching valve 21,
Further, the soil discharge plate cylinders 13 are respectively connected to the soil discharge plate switching valves 22, and each cylinder is controlled by switching these switching valves. Further, the swing switching valve 23 is provided with a swing motor 14, and the left and right travel switching valves 24, 25 are provided with left and right travel motors 15, respectively.
15' is connected, and each motor is driven or stopped by operating the switching valve.

【effect】

In the three-pump hydraulic system of the present invention configured as described above, the swing motor 14 and the bucket cylinder 10 in the same pump system are connected in series via the bucket switching valve 19, so that the supply to the swing motor 14 is The entire amount of pressure oil is supplied to the bucket cylinder 10. Therefore, even if the swivel base 2 and the bucket 5 are operated simultaneously, the disadvantage that pressure oil preferentially flows to the side with lower pressure does not occur. Therefore, multiple operations within the same pump system, namely [swivel + bucket drive], [swivel + boom drive + bucket drive], [swivel + arm drive +
2, 3, or even 4 operations are possible: [bucket drive] and [swivel + arm drive + boom drive + bucket drive]. On the other hand, of the switching valves 20 and 21 for the arm and boom in the same pump system, the third pump 18 is joined only to the boom switching valve 21 via the earth removal plate switching valve 22. Therefore, even if the arm 6 and the boom 7 are operated simultaneously and a large amount of pressure oil is supplied to the arm, the boom can be smoothly operated with the pressure oil from the third pump 18. Therefore, multiple operations within the same pump system, namely [arm drive + boom drive], [swivel + arm drive + boom drive], [arm drive + bucket drive + boom drive], and [swivel + arm drive +
It can perform 2, 3, or even 4 operations (boom drive + bucket drive). Since the third pump 18 is joined to the boom switching valve 21 in this manner, the boom can be operated quickly and smoothly, and a good loading operation can be performed. As detailed above, the three-pump hydraulic system according to the present invention is capable of all kinds of combined operations (two-movement, three-movement, four-movement), and is therefore capable of carrying out loading operations using [swivel + boom drive + arm drive] operations. It can perform all complex operations such as , floor setting work, pressing work, earth removal work, etc., improving work efficiency. In addition, the third pump, which was previously used only for the earth removal plate, has been integrated into the boom switching valve, so it can be used during excavation work, improving overall efficiency and saving energy.

[Brief explanation of the drawing]

Figure 1 is a front view of a backhoe with a soil removal plate incorporating a hydraulic system according to the present invention, and Figure 2 is a front view of a
The illustrated plan view of the vacuum cleaner and FIG. 3 are circuit diagrams of a three-pump hydraulic system according to the present invention. 1...Crawler type traveling vehicle body, 2...Swivel base, 5
...Bucket, 6...Arm, 7...Boom, 9...
...Earth removal plate, 10...Bucket cylinder, 11...
Arm cylinder, 12...Boom cylinder, 13
...Earth removal plate cylinder, 14...Swivel motor, 1
5, 15'...Travel motor, 16, 17, 18...
... Pump, 19... Bucket switching valve, 20... Arm switching valve, 21... Boom switching valve, 22... Earth removal plate switching valve, 23... Swivel switching valve, 24, 25...
...Travel switching valve.

Claims (1)

[Claims] 1 Connecting a swing switching valve, a bucket switching valve, and one running switching valve to the first pump, and connecting an arm switching valve, a boom switching valve, and the other running switching valve to the second pump, In a three-pump hydraulic system of a backhoe equipped with a soil discharge plate formed by connecting a soil discharge plate switching valve to a third pump, a swing switching valve connected to the first pump and one travel switching valve are connected in parallel, The swing switching valve and bucket switching valve are connected in series, the arm switching valve connected to the second pump, the boom switching valve and the other running switching valve are connected in parallel, and the second pump is connected in parallel.
Only the boom switching valve connected to the pump has the third
When the soil discharge plate switching valve connected to the pump is in the neutral position,
A three-pump hydraulic system for a backhoe equipped with an earth removal plate, characterized in that the pressure oil of the third pump is provided to merge the pressure oil of the third pump.