WO2018168179A1

WO2018168179A1 - Construction machine

Info

Publication number: WO2018168179A1
Application number: PCT/JP2018/001069
Authority: WO
Inventors: 平工　賢二; 隆史草間; 相原　三男; 宏政高橋; 自由理清水
Original assignee: 日立建機株式会社
Priority date: 2017-03-14
Filing date: 2018-01-16
Publication date: 2018-09-20
Also published as: JP2018151036A; JP6782183B2

Abstract

Provided is a 2-engine construction machine capable of allowing a hydraulic closed circuit system to be more easily and efficiently mounted in the 2-engine construction machine, and achieving high energy saving performance. The hydraulic closed circuit system is further provided with a second engine (9b), at least four units of closed circuit pumps (12a, 12b, 14a, 14b, 16a, 16b, 18a, 18b) comprise closed circuit pumps (12a, 14a, 16a, 18a) driven by a first engine (9a) and closed circuit pumps (12b, 14b, 16b, 18b) driven by the second engine (9b), and the at least four units of closed circuit pumps have a connection structure in which, when a plurality of solenoid valves (43, 45, 47, 49) are selectively switched to a communication position, every two pumps merge oil discharged from one of two discharge ports on an upstream side of the plurality of solenoid valves, with the merged pressure oil being fed to the plurality of solenoid valves.

Description

Construction machinery

The present invention relates to a hydraulic system for a construction machine, and more particularly to a hydraulic system for a construction machine using a hydraulic closed circuit in which a hydraulic actuator is directly driven by a hydraulic pump.

In recent years, energy saving has become an important development item in construction machines such as hydraulic excavators and wheel loaders. To save energy in construction machinery, it is important to save energy in the hydraulic system itself. A hydraulic system that uses a closed hydraulic circuit (hereinafter referred to as “hydraulic closed circuit”) connects the hydraulic pump and hydraulic actuator in a closed circuit, and supplies and discharges the pressure oil directly between them. Application of “hydraulic closed circuit system”) is under consideration. In the hydraulic closed circuit, there is no pressure loss due to the control valve, and there is no flow rate loss because the pump discharges only the necessary flow rate. Further, the potential energy of the hydraulic actuator and the energy during deceleration can be regenerated. For this reason, it is possible to save energy in the construction machine by applying the hydraulic closed circuit system.

For example, Patent Document 1 discloses a hydraulic closed circuit system applied to a construction machine. In Patent Document 1, each of a plurality of hydraulic pumps is selectively closed-circuited to any one of a plurality of hydraulic actuators via an electromagnetic switching valve, thereby enabling combined operation and high-speed operation of the hydraulic actuators. The configuration is described.

JP 2015-48899 A

For example, an ultra-large excavator for a mine has two engines (or electric motors). As a method of applying the hydraulic closed circuit system to such a construction machine having two engines, it is conceivable to mount two hydraulic closed circuit systems for one engine excavator described in Patent Document 1.

Here, the hydraulic closed circuit system described in Patent Document 1 includes a large number of electromagnetic switching valves so that a plurality of bidirectional discharge hydraulic pumps can be connected in a closed circuit to a plurality of hydraulic actuators. And since most of the hydraulic valve block is constituted by these many electromagnetic switching valves, the longitudinal dimension (left-right direction) of the hydraulic valve block increases in proportion to the number of electromagnetic switching valves. For this reason, when two hydraulic closed circuit systems described in Patent Document 1 are mounted, the size of the hydraulic valve block in the left-right direction is approximately doubled by doubling the number of switching valves.

However, in a two-engine super-large excavator, the horizontal dimension (width dimension) of the mounting space for the hydraulic valve block is 1.3 times (2 times the size) even if the fuselage volume is increased to twice that of one engine excavator, for example. The width of the mounting space for the hydraulic valve block cannot be doubled due to the provision of a vehicle body structure that can be divided into sizes that can be transported by truck. For this reason, it is difficult to fit a hydraulic valve block in which a double number of electromagnetic switching valves are arranged in a single row on the left and right sides to a width of 1.3 times. Similarly, the vertical and longitudinal dimensions of the hydraulic valve block are also increased by about 1.3 times (twice the cube root), so the hydraulic valve block is divided into two parts, and the vertical and longitudinal dimensions are 2 It is also difficult to arrange them side by side. Therefore, it is not easy to mount two hydraulic closed circuit systems for one engine excavator described in Patent Document 1 on a two-engine super large excavator.

The present invention has been made in view of the above problems, and an object of the present invention is to improve the mountability of a hydraulic closed circuit system on a two-engine construction machine and realize high energy saving. Is to provide.

In order to achieve the above object, the present invention provides a lower traveling body, an upper revolving body that is rotatably mounted on the lower traveling body, and a front device that is rotatably attached to the upper revolving body in the vertical direction. And a first prime mover, a plurality of hydraulic pumps for closed circuit having two discharge ports, a plurality of hydraulic actuators, and a plurality of electromagnetic switching valves, and selectively selecting the plurality of electromagnetic switching valves The two discharge ports of the plurality of hydraulic pumps are selectively connected to at least some of the plurality of hydraulic actuators, and at least one of the plurality of hydraulic pumps and the plurality of hydraulic actuators is switched to the communication position. In a construction machine including a hydraulic closed circuit system that forms a closed circuit with a part of the machine, the hydraulic closed circuit system further includes a second prime mover, and the plurality of hydraulic pressures The pump includes at least four hydraulic pumps, and the at least four hydraulic pumps include a hydraulic pump driven by the first prime mover and a hydraulic pump driven by the second prime mover, and at least four of the hydraulic pumps In the hydraulic pump, when the plurality of electromagnetic switching valves are selectively switched to the communication position, two pumps discharge oil from one of the two discharge ports upstream of the plurality of electromagnetic switching valves. It has a connection structure in which the joined pressure oil is supplied to the plurality of electromagnetic switching valves.

According to the present invention configured as above, the discharge port of the hydraulic pump driven by the first prime mover and the discharge port of the hydraulic pump driven by the second prime mover are connected to the pump 2 upstream of the plurality of electromagnetic switching valves. By joining the units one by one, the number of electromagnetic switching valves constituting most of the hydraulic valve block can be suppressed to the same level as the hydraulic closed circuit system for one engine excavator. As a result, each dimension of the hydraulic valve block can be kept small, so that the hydraulic closed circuit system can be easily mounted on a two-engine hydraulic excavator. By installing a hydraulic closed circuit system, it is possible to achieve high energy savings in a two-engine construction machine.

According to the present invention, the mountability of the hydraulic closed circuit system on a two-engine construction machine is improved, and high energy saving can be realized in the two-engine construction machine.

1 is a side view of a hydraulic excavator according to a first embodiment of the present invention. FIG. 2 is a horizontal sectional view of the upper swing body shown in FIG. 1. FIG. 2 is a hydraulic circuit diagram of a hydraulic closed circuit system mounted on the hydraulic excavator shown in FIG. 1. It is a hydraulic circuit diagram of a hydraulic closed circuit system mounted on a hydraulic excavator according to a second embodiment of the present invention.

Hereinafter, a hydraulic excavator will be described as an example of a construction machine according to an embodiment of the present invention and will be described with reference to the drawings. In addition, in each figure, the same code | symbol is attached | subjected to an equivalent member and the overlapping description is abbreviate | omitted suitably.

FIG. 1 is a side view of a hydraulic excavator according to a first embodiment of the present invention. FIG. 2 is a horizontal sectional view of the upper swing body 102 shown in FIG. FIG. 3 is a hydraulic circuit diagram of a hydraulic closed circuit system mounted on the hydraulic excavator 100 shown in FIG.

As shown in FIG. 1, a hydraulic excavator 100 is mounted on a lower traveling body 101 equipped with crawler-type left and right traveling apparatuses 101a and 101b, and on the lower traveling body 101 so as to be capable of turning via a turning device 102a. The upper swing body 102 and a front device 103 attached to the front side of the upper swing body 102 so as to be rotatable in the vertical direction are provided. The traveling devices 101 a and 101 b are driven by hydraulic motors (hereinafter referred to as “traveling motors”) 8 a and 8 b, and the turning device 102 a is driven by a hydraulic motor (hereinafter referred to as “swing motor”) 7.

The upper swing body 102 includes a swing frame 104, a counterweight 105, and a cab 106. The turning frame 104 is a basic lower structure of the upper turning body 102, and a front device 103 is attached to the front portion of the turning frame 104 so as to be rotatable in the vertical direction. A counterweight 105 that balances the weight with the front device 103 is provided on the rear end side of the revolving frame 104. A cab 106 on which an operator rides is provided on the left side of the front part 103 and on the left side of the front part of the turning frame 104.

The front device 103 includes a boom 2 whose base end is attached to the front portion of the swing frame 104 so as to be rotatable in the vertical direction, and an arm that is attached to the distal end portion of the boom 2 so as to be rotatable in the vertical and forward / backward directions. 4, a bucket 6 attached to the tip of the arm 4 so as to be pivotable in the vertical and longitudinal directions, a single rod hydraulic cylinder (hereinafter referred to as “boom cylinder”) 1 for pivoting the boom 2, and an arm 4. Are provided with a single rod hydraulic cylinder (hereinafter referred to as “arm cylinder”) 3 and a single rod hydraulic cylinder (hereinafter referred to as “bucket cylinder”) 5 for rotating the bucket 6.

As shown in FIG. 2, the upper-part turning body 102 includes a left engine room (first machine room) 107 disposed on the left side (lower side in FIG. 2) on the turning frame 104 and a right side ( And a right engine room (second machine room) 108 disposed on the upper side in FIG. Two engines (or electric motors) 9a and 9b having the same output are mounted on the rear sides of the left and

right engine rooms

107 and 108, respectively. Hereinafter, as appropriate, the engine 9a mounted in the left engine room 107 is referred to as a “left engine”, and the engine 9b mounted in the right engine room 108 is referred to as a “right engine”. Each

engine

9a, 9b drives a plurality of hydraulic pumps 12a-19a, 12b-19b via

power transmission devices

10a, 10b comprising a plurality of gear trains. The pressure oil discharged from the plurality of hydraulic pumps 12a to 19a, 12b to 19b is supplied to a hydraulic valve block 70, which will be described later, including a large number of electromagnetic switching valves and the like through piping (not shown).

Radiators

20a and 20b are disposed behind the left and

right engines

9a and 9b, respectively.

Radiator cooling fans

21a and 21b are attached to the rear sides of the left and

right engines

9a and 9b, respectively. The

radiator cooling fans

21a and 21b are driven by the left and

right engines

9a and 9b to supply the generated cooling air to the

radiators

20a and 20b. Thus, the

radiators

20a and 20b exchange the heat of the engine cooling water heated by the left and

right engines

9a and 9b with the cooling air.

Between the left and

right engine rooms

107 and 108, a fuel tank 22 for storing the fuel of the left and

right engines

9a and 9b and a hydraulic oil tank 23 for storing the hydraulic oil of the hydraulic pumps 12a to 19a and 12b to 19b are arranged. Has been. Between the left and

right engine rooms

107 and 108 and on the front side of the fuel tank 22 and the hydraulic oil tank 23, hydraulic pumps 12a to 19a and 12b to 19b are connected to the

hydraulic actuators

1, 3, 5, 7, 8a and 8b. A hydraulic valve block 70 for controlling the flow of pressure oil is disposed.

An oil cooler 24 and an oil cooler cooling fan 25 attached to the oil cooler 24 are disposed on the front side of the right engine room 108. The oil cooler cooling fan 25 is driven by a motor to supply the generated cooling air to the oil cooler 24. As a result, the oil cooler 24 exchanges heat with the cooling air from the return oil from the

hydraulic actuators

1, 3, 5, 7, 8 a, 8 b and returns to the hydraulic oil tank 23.

A left passage 109 a is formed on the left side of the upper swing body 102, a right passage 109 b is formed on the right side of the upper swing body 102, and a substantially L-shaped central passage 109 c is formed at the center of the upper swing body 102. ing.

The upper turning body 102 has a structure that can be divided for mounting on a truck to be transported to the mine site. The left part is based on the left frame 104a, the right part is based on the right frame 104b, and the center frame 104c is the basis. And the counterweight 105 is divided into at least four. Here, the turning frame 104 has a structure in which the left and

right frames

104a and 104b are mounted on the center frame 104c and fastened, and the left and

right engine rooms

107 and 108 are mounted on the left and

right frames

104a and 104b, respectively. For this reason, the hydraulic valve block 70 needs to be accommodated in the width dimension W sandwiched between the two

engine rooms

107 and 108.

Here, when two conventional hydraulic closed circuit systems for a single engine excavator are to be mounted on the two-engine hydraulic excavator 100, the number of electromagnetic switching valves occupying most of the hydraulic valve block 70 is doubled. As a result, the dimension in the longitudinal direction (left-right direction) of the hydraulic valve block 70 is increased approximately twice. However, in the two-engine hydraulic excavator 100, even if the body volume increases, for example, twice, the horizontal dimension (width dimension W) of the mounting space of the hydraulic valve block 70 is 1.3 times (twice the third power). Root) only increases, and because of the restrictions on the transport size described above, the width W cannot be doubled. Therefore, it is difficult to fit the hydraulic valve block 70 in which the switching valves are arranged in the left and right rows within the width dimension W. Similarly, each dimension in the vertical and longitudinal directions of the hydraulic valve block 70 is also increased by about 1.3 times (twice the third root), so the hydraulic valve block 70 is divided into two, and the vertical and longitudinal directions. It is also difficult to arrange two of them side by side. Therefore, it is not easy to mount two conventional hydraulic closed circuit systems for one engine excavator on the two-engine hydraulic excavator 100.

Therefore, in the present invention, as shown in the hydraulic circuit diagram of FIG. 3, two hydraulic pumps are joined together and then connected to the electromagnetic switching valve, so that the number of electromagnetic switching valves is reduced to the hydraulic closed circuit of one engine excavator. The mounting performance was improved by keeping the hydraulic valve block within the width W shown in FIG.

Hereinafter, the hydraulic circuit diagram of FIG. 3 will be described. Note that the closed circuit for the hydraulic circuit protects the circuit by specifying a charge pump for maintaining the normal circuit pressure, a flushing valve for compensating for excess or deficiency of oil in the closed circuit, a make-up check valve, and the maximum circuit pressure. A relief valve or the like is provided for the purpose of illustration, but is omitted here in order to avoid complication of notation.

In FIG. 3, the left engine 9a is a bi-directional discharge type variable displacement hydraulic pump (hereinafter referred to as “closed circuit pump” as appropriate) 12a, 14a, 16a, 18a, a one-way discharge type via a power transmission device 10a. Variable displacement hydraulic pumps (hereinafter referred to as “open circuit pumps” as appropriate) 13a, 15a, 17a, 19a are driven. The right engine 9b drives the closed circuit pumps 12b, 14b, 16b, 18b and the open circuit pumps 13b, 15b, 17b, 19b via the power transmission device 10b.

One discharge port 12c of the closed circuit pump 12a joins with one discharge port 12d of the closed circuit pump 12b, and then merges with an electromagnetic switching valve (hereinafter simply referred to as “switching valve”) 43a to 43c via one combined oil passage 31a. The other discharge port 12e of the closed circuit pump 12a is connected to the other discharge port 12f of the closed circuit pump 12b and then connected to the switching valves 43a to 43d via the other combined oil passage 31b. Yes.

One discharge port 14c of the closed circuit pump 14a merges with one discharge port 14d of the closed circuit pump 14b and is connected to the switching valves 45a to 45d via one merged oil passage 31c, and the other of the closed circuit pump 14a. The discharge port 14e joins with the other discharge port 14f of the closed circuit pump 14b, and is then connected to the switching valves 45a to 45d via the other combined oil passage 31d.

One discharge port 16c of the closed circuit pump 16a joins with one of the discharge ports 16d of the closed circuit pump 16b and then is connected to the switching valves 47a to 47d through one merged oil passage 31e, and the other of the closed circuit pump 16a. The discharge port 16e joins with the other discharge port 16f of the closed circuit pump 16b, and then is connected to the switching valves 47a to 47d via the other combined oil passage 31f.

One discharge port 18c of the closed circuit pump 18a joins with one of the discharge ports 18d of the closed circuit pump 18b and then is connected to the switching valves 49a to 49d via one merged oil passage 31g, and the other of the closed circuit pump 18a. The discharge port 18e joins with the other discharge port 18f of the closed circuit pump 18b and is then connected to the switching valves 49a to 49d via the other combined oil passage 31h.

The switching valve 43a is connected to the boom cylinder 1 via a pair of

actuator oil passages

32a and 32b. The switching valve 43a opens and closes in response to a signal from the controller 41. When no signal is input from the controller 41, the switching valve 43a is in the shut-off position, and the pair of combined oil passages 31a and 31b are shut off from the pair of

actuator oil passages

32a and 32b. On the other hand, when a signal is input from the controller 41, the switching valve 43a is in the communication position, and the pair of merging oil passages 31a and 31b are electrically connected to the pair of

actuator oil passages

32a and 32b. Here, when the switching valve 43a is in the communication position, the other switching

valves

43b, 43c, 43d connected to the pair of merging oil passages 31a, 31b are all controlled to be in the blocking position. Thus, when the switching valve 43a is in the communication position, the closed circuit pumps 12a and 12b are closed circuit connected to the boom cylinder 1 via the pair of merged oil passages 31a and 31b and the pair of

actuator oil passages

32a and 32b. .

The switching valve 43b is connected to the arm cylinder 3 via a pair of actuator oil passages 32c and 32d. The switching valve 43b opens and closes in response to a signal from the controller 41. When no signal is input from the controller 41, the switching valve 43b is in the shut-off position, and the pair of combined oil passages 31a and 31b are shut off from the pair of actuator oil passages 32c and 32d. On the other hand, when a signal is input from the controller 41, the switching valve 43b is in the communication position, and the pair of merging oil passages 31a and 31b communicate with the pair of actuator oil passages 32c and 32d. Here, when the switching valve 43b is in the communication position, the

other switching valves

43a, 43c, 43d connected to the pair of merging oil passages 31a, 31b are all controlled to be in the blocking position. Thus, when the switching valve 43b is in the communication position, the closed circuit pumps 12a and 12b are closed circuit connected to the arm cylinder 3 via the pair of merging oil passages 31a and 31b and the pair of actuator oil passages 32c and 32d. .

The switching valve 43c is connected to the bucket cylinder 5 through a pair of

actuator oil passages

32e and 32f. The switching valve 43c opens and closes in response to a signal from the controller 41. When no signal is input from the controller 41, the switching valve 43c is in the shut-off position, and the pair of combined oil passages 31a and 31b are shut off from the pair of

actuator oil passages

32e and 32f. On the other hand, when a signal is input from the controller 41, the switching valve 43c is in the communication position, and the pair of merging oil passages 31a and 31b communicate with the pair of

actuator oil passages

32e and 32f. Here, when the switching valve 43c is in the communication position, the

other switching valves

43a, 43b, 43d connected to the pair of merging oil passages 31a, 31b are all controlled to be in the blocking position. Thus, when the switching valve 43c is in the communication position, the closed circuit pumps 12a and 12b are closed circuit connected to the bucket cylinder 5 via the pair of merging oil passages 31a and 31b and the pair of

actuator oil passages

32e and 32f. .

The switching valve 43d is connected to the turning motor 7 through a pair of

actuator oil passages

32g and 32h. The switching valve 43d opens and closes in response to a signal from the controller 41. When no signal is input from the controller 41, the switching valve 43d is in the cutoff position, and the pair of combined oil passages 31a and 31b are shut off from the pair of

actuator oil passages

32g and 32h. On the other hand, when a signal is input from the controller 41, the switching valve 43d is in the communication position, and the pair of merging oil passages 31a and 31b communicate with the pair of

actuator oil passages

32g and 32h. Here, when the switching valve 43d is in the communication position, the

other switching valves

43a, 43b, 43c connected to the pair of merging oil passages 31a, 31b are all controlled to be in the blocking position. Thus, when the switching valve 43d is in the communication position, the closed circuit pumps 12a and 12b are closed circuit connected to the swing motor 7 via the pair of merging oil passages 31a and 31b and the pair of

actuator oil passages

32g and 32h. .

Thus, the switching valves 43a to 43d selectively connect the closed circuit pumps 12a and 12b to any one of the plurality of

hydraulic actuators

1, 3, 5, and 7, and the closed circuit pumps 12a and 12b and the hydraulic actuators A closed circuit is formed between 1, 3, 5, and 7. Similarly, the switching valves 45a to 45d selectively connect the closed circuit pumps 14a and 12b to any one of the plurality of

hydraulic actuators

1, 3, 5 and 7, and the closed circuit pumps 12a and 12b and the

hydraulic actuator

1 , 3, 5 and 7 form a closed circuit. The switching valves 47a to 47d selectively connect the closed circuit pumps 16a, 16 to any one of the plurality of

hydraulic actuators

1, 3, 5, 7, and the

closed circuit pumps

16a, 16b and the

hydraulic actuators

1, 3, A closed circuit is formed between 5 and 7. The switching valves 49a to 49d selectively connect the closed circuit pumps 18a and 18b to any one of the plurality of

hydraulic actuators

1, 3, 5, and 7, and the closed circuit pumps 18a and 18b and the

hydraulic actuators

1, 3, and 3 A closed circuit is formed between 5 and 7.

The discharge port 13c of the open circuit pump 13a joins with the discharge port 13d of the open circuit pump 13b, and then is connected to the switching valves 44a to 44d and the bleed-off valve 64 via the merged oil passage 33a. The discharge port 15c of the open circuit pump 15a and the discharge port 15d of the open circuit pump 15b are connected to the switching valves 46a to 46d and the bleed-off valve 65 after merging in the merging oil passage 33b. The discharge port 17c of the open circuit pump 17a merges with the discharge port 17d of the open circuit pump 17b, and then is connected to the switching valves 48a to 48d and the bleed-off valve 66 through the merged oil passage 33c. The discharge port 19c of the open circuit pump 19a joins with the discharge port 19d of the open circuit pump 19b, and then is connected to the switching valves 50a to 50d and the bleed-off valve 67 via the merged oil passage 33d.

The switching valve 44a is connected to the bottom side of the boom cylinder 1 via the actuator oil passage 32b. The switching valve 44a opens and closes in response to a signal from the controller 41. When no signal is input from the controller 41, the switching valve 44a is in the cutoff position, and the merged oil passage 33a is cut off from the actuator oil passage 32b. On the other hand, when a signal is input from the controller 41, the switching valve 44a is in the communication position, and the merged oil passage 33a communicates with the actuator oil passage 32b. Here, when the switching valve 44a is in the communication position, the other switching valves 44b to 44d connected to the merging oil passage 33a are all controlled to be in the cutoff position. Thus, when the switching valve 44a is in the communication position, the open circuit pumps 13a and 13b are connected to the bottom side of the boom cylinder 1 via the merged oil passage 33a and the actuator oil passage 32b.

The switching valve 44b is connected to the bottom side of the arm cylinder 3 via the actuator oil passage 32d. The switching valve 44b opens and closes in response to a signal from the controller 41. When no signal is input from the controller 41, the switching valve 44b is in the cutoff position, and the merged oil passage 33a is cut off from the actuator oil passage 32d. On the other hand, when a signal is input from the controller 41, the switching valve 44b is in the communication position, and the merging oil passage 33a is electrically connected to the actuator oil passage 32d. Here, when the switching valve 44b is in the communication position, the other switching valves 44a, 44c, 44d connected to the merging oil passage 33a are all controlled to be in the cutoff position. As a result, when the switching valve 44b is in the communication position, the open circuit pumps 13a and 13b are connected to the bottom side of the arm cylinder 3 via the merging oil passage 33a and the actuator oil passage 32d.

The switching valve 44c is connected to the bottom side of the bucket cylinder 5 via the actuator oil passage 32f. The switching valve 44c opens and closes in response to a signal from the controller 41. When no signal is input from the controller 41, the switching valve 44c is in the cutoff position, and the merged oil passage 33a is cut off from the actuator oil passage 32f. On the other hand, when a signal is input from the controller 41, the switching valve 44c is in the communication position, and the merging oil passage 33a is electrically connected to the actuator oil passage 32f. Here, when the switching valve 44c is in the communication position, the other switching valves 44a, 44b, 44d connected to the merging oil passage 33a are all controlled to be in the cutoff position. As a result, when the switching valve 44c is in the communication position, the open circuit pumps 13a and 13b are connected to the bottom side of the bucket cylinder 5 via the merging oil passage 33a and the actuator oil passage 32f.

The switching valve 44d is connected to the control valve 54 via the pressure oil supply oil passage 34. The control valve 54 is connected to the left travel motor 8a via a pair of

actuator oil passages

35a and 35b. The switching valve 44d opens and closes in response to a signal from the controller 41. When no signal is input from the controller 41, the switching valve 44d is in the cutoff position, and the merged oil passage 33a is cut off from the pressure oil supply oil passage 34. On the other hand, when a signal is input from the controller 41, the switching valve 44d is in the communication position, and the merging oil passage 33a is electrically connected to the pressure oil supply oil passage. Here, when the switching valve 44d is in the communication position, the other switching valves 44a to 44c connected to the merging oil passage 33a are all controlled to be in the cutoff position. Thus, when the switching valve 44d is in the communication position, the open circuit pumps 13a and 13b travel left via the merging oil passage 33a, the pressure oil supply oil passage 34, the control valve 54, and the pair of

actuator oil passages

35a and 35b. Connected to the motor 8a. The control valve 54 adjusts the rotational direction and rotational speed of the left traveling motor 8a by controlling the flow of pressure oil supplied to and discharged from the left traveling motor 8a in accordance with a command from the controller 41.

Thus, the switching valves 44a to 44d selectively connect the open circuit pumps 13a and 13b to any one of the bottom sides of the

hydraulic cylinders

1, 3, and 5 or the left traveling motor 8a. Similarly, the switching valves 46a to 46d selectively connect the open circuit pumps 15a and 15b to any one of the bottom sides of the plurality of

hydraulic cylinders

1, 3, and 5 or the left traveling motor 8a. The switching valves 48a to 48d selectively connect the open circuit pumps 17a and 17b to any one of the bottom sides of the plurality of

hydraulic cylinders

1, 3, and 5 or the right traveling motor 8b. The switching valves 50a to 50d selectively connect the open circuit pumps 19a and 19b to any one of the bottom sides of the plurality of

hydraulic cylinders

1, 3, and 5 or the right traveling motor 8b.

The combined oil passages 33a to 33d connected to the

open circuit pumps

13a, 13b, 15a, 15b, 17a, 17b, 19a, and 19b are connected to the hydraulic oil tank 23 via bleed-off valves 64 to 67, respectively. . The bleed-off valves 64 to 67 are opened and closed in response to a signal from the controller 41, and a part of the pressure oil discharged from the bottom side of each

hydraulic cylinder

1, 3, 5 is discharged to the hydraulic oil tank 23.

The switching valves 43 to 50 and the bleed-off valves 64 to 67 are integrated as a hydraulic valve block 70 and mounted on the center frame 104c (shown in FIG. 2).

The operation of the hydraulic closed circuit system configured as described above will be described by taking the case of operating the boom cylinder 1 as an example.

When the boom cylinder 1 is extended, for example, the switching valves 43a and 44a are turned on, and pressure oil is discharged from the closed circuit pumps 12a and 12b and the open circuit pumps 13a and 13b. Thereby, the flow volume for four pumps flows into the bottom side of the boom cylinder 1, and the boom cylinder 1 extends. The discharge flow rate from the rod side of the boom cylinder 1 is sucked into the closed circuit pumps 12a and 12b, but if the flow rate becomes excessive, it is discharged from a flushing valve (not shown) to the charge pressure line outside the closed circuit, and the flow rate is insufficient. If this happens, the hydraulic fluid is sucked into the closed circuit from the charge line via the flushing valve or makeup check valve.

In addition, the extension speed of the cylinder can be increased by increasing the number of hydraulic pumps connected to the boom cylinder 1. For example, by making the switching

valves

43a, 45a, 47a, 49a, 44a, 46a, 48a, and 50a conductive, it is possible to perform a high-speed extension operation using all 16 hydraulic pumps.

On the other hand, when the retracting operation of the boom cylinder 1 is performed, the switching valves 43a and 44a are turned on, the closed circuit pumps 12a and 12b are discharged in the opposite direction, and the bleed-off valve 64 is opened. As a result, the pressure oil is discharged from the bottom side of the boom cylinder 1, and the boom cylinder 1 is retracted.

The arm cylinder 3 and the bucket cylinder 5 can be operated in the same manner as the boom cylinder 1. Further, by selectively switching the plurality of switching valves 43 to 50 to the communication position and connecting a hydraulic pump to two or more of the plurality of

hydraulic actuators

1, 3, 5, 7, 8a, 8b, a plurality of hydraulic pressures are obtained. Two or more of the

actuators

1, 3, 5, 7, 8a, and 8b can be simultaneously operated (combined operation).

According to the hydraulic excavator 100 according to the present embodiment configured as described above, the discharge ports of the plurality of closed circuit pumps (hydraulic pumps) 12a, 14a, 16a, 18a driven by the left engine (first prime mover) 9a Discharge ports of a plurality of closed circuit pumps (hydraulic pumps) 12b, 14b, 16b, 18b driven by the right engine (second prime mover) 9b are pumps 2 upstream of the plurality of electromagnetic switching valves 43, 45, 47, 49. The discharge ports of the plurality of

open circuit pumps

13a, 15a, 17a, 19b driven by the left engine 9a and the discharge ports of the plurality of open circuit pumps 13b, 15b, 17b, 19b driven by the right engine 9b The ports are joined by two pumps on the upstream side of the plurality of

electromagnetic switching valves

44, 46, 48, 50. As a result, the number of switching valves 43 to 50 constituting most of the hydraulic valve block 70 can be suppressed to the same level as the hydraulic closed circuit system for one engine excavator. As a result, the horizontal dimension of the hydraulic valve block 70 is kept small, and the hydraulic valve block 70 fits in the width dimension W sandwiched between the

engine rooms

107 and 108, so that the hydraulic closed circuit system is replaced with a two-engine hydraulic excavator 100. Can be easily mounted. By mounting the hydraulic closed circuit system, high energy saving performance can be realized in the two-engine hydraulic excavator 100.

Here, two hydraulic pumps are connected to each of the switching valves 43 to 50, and the passage flow rate of each switching valve 43 to 50 is doubled as compared with a hydraulic closed circuit system for one engine excavator. For this reason, when the rated capacity of the switching valves 43 to 50 is set to be the same as that of the hydraulic closed circuit system of one engine excavator, the energy loss is slightly reduced due to an increase in pressure loss in the switching valves 43 to 50. In order to improve this, the rated capacity of the switching valves 43 to 50 may be set to double. Even if the rated flow rate is set to twice, the outer dimensions of the switching valves 43 to 50 only increase by 1.3 times (twice the third root), and the outer dimensions of the hydraulic valve block 70 are also 1.3 times. It only increases to a certain extent. Therefore, even if the rated flow rate of the switching valves 43 to 50 is doubled, the hydraulic valve block 70 can be accommodated in the width dimension W sandwiched between the

engine rooms

107 and 108.

Further, by combining two hydraulic pumps, one each included in the plurality of hydraulic pumps 12a to 19a driven by the left engine 9a and the plurality of hydraulic pumps 12b to 19b driven by the right engine 9b, for example, Even when the left engine 9a fails and does not operate, the switching valves 43 to 50 are selectively switched to the communication position, and the hydraulic pumps 12b to 19b driven by the right engine 9b are connected to the plurality of

hydraulic actuators

1, 3, and 3. 5, 7, 8a, 8b. As a result, even if one engine fails, the excavator 100 can continue to operate, or the vehicle body can be moved to a place where engine repair is possible, and downtime can be minimized. Improves.

In addition, by combining the plurality of hydraulic pumps 12a to 19a, 12b to 19b with two pumps upstream of the plurality of electromagnetic switching valves 43 to 50, the discharge oil from each of the hydraulic pumps 12a to 19a and 12b to 19b can be used. Delivery filters (not shown) for removing foreign substances are not the discharge ports 12c-12f, 13c, 13d, 14c-14f, 15c, 15d, 16c-16f, 17c, 17d, 18c-18f, 19c, 19d, What is necessary is just to provide in the confluence | merging oil path 31a-31h and 33a-33d where the discharge oil of two hydraulic pumps merges, respectively. Thereby, the number of delivery filters can be suppressed to the same level as the hydraulic closed circuit system for one engine excavator.

Here, in the excavator 100, horsepower control is performed in which the discharge amount of the hydraulic pump is changed in accordance with the increase or decrease of the engine rotation speed to effectively use the engine horsepower. This is because when the engine speed is higher than the set speed, the pump absorption horsepower is increased to increase the engine load and increase the operating speed of the actuator, and when the engine speed is lower than the set speed, the pump absorption horsepower is decreased. The engine load is reduced to protect the engine from overload and prevent engine stall. The pump absorption horsepower is represented by the product of the pump flow rate and the pump pressure, and the pump flow rate, that is, the pump discharge amount is controlled while observing the pump pressure so that the total absorption horsepower of the pump does not exceed the engine horsepower.

In the hydraulic closed circuit system shown in FIG. 3, two hydraulic pumps are included, one each in the plurality of hydraulic pumps 12a to 19a driven by the left engine 9a and the plurality of hydraulic pumps 12b to 19b driven by the right engine 9b. Are combined, for example, the discharge pressures of the closed circuit pumps 12a and 12b are equal, the discharge pressures of the open circuit pumps 13a and 13b are equal, and so on. For this reason, by controlling the pump discharge amount of each pair of the hydraulic pumps 12a to 19a of the left engine 9a and the hydraulic pumps 12b to 19b of the right engine 9b, the total absorption horsepower of the pumps can be increased by the left engine 9a and the right engine 9b. And are equal. As a result, the control of the absorption horsepower of the hydraulic pump can be made the same for each pump pair, so that the hydraulic closed circuit system includes two

engines

9a and 9b and 16 hydraulic pumps 12a to 19a and 12b to 19b. However, it can be handled equivalently to a hydraulic closed circuit system for one engine excavator having one engine and eight hydraulic pumps, and the control is simplified, so that the reliability can be improved. In addition, since the loads of the two

engines

9a and 9b are equal, the degree of aging of the

engines

9a and 9b is also equal, and maintenance cycles such as oil change and overhaul can be made the same, improving long-term reliability. Can contribute.

FIG. 4 shows a hydraulic circuit diagram of a hydraulic closed circuit system mounted on a hydraulic excavator according to a second embodiment of the present invention. Similarly to the first embodiment (shown in FIG. 3), the hydraulic closed circuit system according to the present embodiment is switched by combining two hydraulic pumps and then connecting to the switching valves 43 to 50. The number of valves 43 to 50 is suppressed to the same level as that of a hydraulic closed circuit system for one engine excavator, and the hydraulic valve block 70 can be easily accommodated in the width dimension W sandwiched between the left and

right engine rooms

107 and 108. Is an improvement. Hereinafter, the difference from the first embodiment will be mainly described.

In FIG. 4, one discharge port 12c of the closed circuit pump 12a driven by the left engine 9a merges with one discharge port 14c of the closed circuit pump 14a similarly driven by the left engine 9a, and then one combined oil. The other discharge port 12e of the closed circuit pump 12a joins with the other discharge port 14e of the closed circuit pump 14a and is then connected via the merged oil passage 31b. 43a to 43d.

One discharge port 16c of the closed circuit pump 16a driven by the left engine 9a merges with one discharge port 18c of the closed circuit pump 18a similarly driven by the left engine 9a, and then passes through one merged oil passage 31c. The other discharge port 16e of the closed circuit pump 16a merges with the other discharge port 18e of the closed circuit pump 18a, and then is connected to the switch valves 45a to 45d via the merged oil passage 31d. It is connected.

One discharge port 12d of the closed circuit pump 12b driven by the right engine 9b merges with one discharge port 14d of the closed circuit pump 14b also driven by the right engine 9b, and then passes through one merged oil passage 31e. The other discharge port 12f of the closed circuit pump 12b joins with the other discharge port 14f of the closed circuit pump 14b, and then is connected to the switch valves 47a to 47d via the merged oil passage 31f. It is connected.

One discharge port 16d of the closed circuit pump 16b driven by the right engine 9b merges with one discharge port 18f of the closed circuit pump 18b also driven by the right engine 9b, and then passes through one merged oil passage 31g. The other discharge port 16f of the closed circuit pump 16b joins with the other discharge port 18f of the closed circuit pump 18b, and then joins the changeover valves 49a to 49d via the merged oil passage 31h. It is connected.

The discharge port 13c of the open circuit pump 13a driven by the left engine 9a merges with the discharge port 15c of the open circuit pump 15a also driven by the left engine 9a, and then switches the switching valves 44a to 44d via the merged oil passage 33a. And a bleed-off valve 64.

The discharge port 17c of the open circuit pump 17a driven by the left engine 9a merges with the discharge port 19c of the open circuit pump 19a also driven by the left engine 9a, and then the switching valves 48a to 48d via the merged oil passage 33c. And a bleed-off valve 66.

The discharge port 13d of the open circuit pump 13b driven by the right engine 9b merges with the discharge port 15d of the open circuit pump 15b also driven by the right engine 9b, and then switches the switching valves 46a to 46d via the merged oil passage 33b. And a bleed-off valve 65.

The discharge port 17d of the open circuit pump 17b driven by the right engine 9b merges with the discharge port 19d of the open circuit pump 19b also driven by the right engine 9b, and then switches the switching valves 50a to 50d via the merged oil passage 33d. And a bleed-off valve 67.

Also in the present embodiment configured as described above, the same effects as in the first embodiment can be obtained.

Further, the closed circuit pumps driven by the same engine (that is, arranged close to each other) and the open circuit pumps are merged in the

engine rooms

107 and 108, and the merged pipes (merged oil paths 31a to 31a) are joined. 31h, 33a to 33d) are connected to the switching valves 43 to 50, so that a total of 24 pipes (discharge ports 12c to 12f, 13c, 13d, 14c to 14f, 15c, 15d, 16c to 16f, 17c, 17d, 18c to 18f, 19c, and 19d) do not need to be routed outside the

engine rooms

107 and 108, and a total of 12 pipes after joining (merging oil passages 31a to 31h, 33a to 33d) ) Only from the engine compartments 107 and 108 to the hydraulic valve block 70, so that the mountability is greatly improved as compared with the first embodiment. It is possible to improve. In the example shown in FIG. 4, in each

engine room

107, 108, the closest closed circuit pumps and the open circuit pumps form a pair, but the present invention is not limited to this, and the same A pair may be formed in any way as long as the closed circuit pumps arranged in the engine room and the open circuit pumps are arranged.

Also, in the hydraulic excavator according to the present embodiment, when one of the engines fails and the operation is stopped, the hydraulic excavator 100 can be operated by the other engine. For example, an example will be described in which when the left engine 9a breaks down and stops operating, the hydraulic pumps 12b to 19b are driven only by the right engine 9b and the boom cylinder 1 is extended to travel. First, the boom cylinder 1 is extended by switching the switching valve 47a to the communication position and discharging the pressure oil from the closed circuit pumps 12b and 14b. The switching valve 46d is switched to the communication position, pressure oil is discharged from the open circuit pumps 13b and 15b, and the control valve 54 is opened to drive the left travel motor 8a, and the switching valve 50d is switched to the communication position. The right traveling motor 8b is driven by discharging pressure oil from 17b and 19b and opening the control valve 55. Thereby, the vehicle body can travel back and forth while raising the boom 2. Further, the arm 4, the bucket 6, and the turning device 102a can be driven in the same manner as the boom 1 by selectively switching the plurality of electromagnetic switching valves 43 to 50 to the communication position.

As mentioned above, although the Example of this invention was explained in full detail, this invention is not limited to an above-described Example, Various modifications are included. For example, the above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described. It is also possible to add a part of the configuration of another embodiment to the configuration of a certain embodiment, and delete a part of the configuration of a certain embodiment or replace it with a part of another embodiment. Is possible. In the above-described embodiment, the present invention is applied to a hydraulic excavator equipped with two engines. However, the present invention is not limited to this, and the present invention is also applied to a construction machine such as a crane equipped with two engines. Applicable.

DESCRIPTION OF SYMBOLS 1 ... Boom cylinder, 2 ... Boom, 3 ... Arm cylinder, 4 ... Arm, 5 ... Bucket cylinder, 6 ... Bucket, 7 ... Turning motor, 8a, 8b ... Traveling motor, 9a ... Left engine, 9b ... Right engine, 10a , 10b ... power transmission device, 12a, 12b, 14a, 14b, 16a, 16b, 18a, 18b ... closed circuit pump (hydraulic pump), 12c-12f, 14c-14f, 16c-16f, 18c-18f ... discharge port, 13a, 13b, 15a, 15b, 17a, 17b, 19a, 19b ... open circuit pump, 13c, 13d, 15c, 15d, 17c, 17d, 19c, 19d ... discharge port, 20a, 20b ... radiator, 21a, 21b ... radiator Cooling fan, 22 ... fuel tank, 23 ... hydraulic oil tank, 24 ... oil cooler, 25 ... oi Cooling fan for cooler, 31a to 31h, 33a to 33d ... Merge oil passage, 32a to 32h, 35a, 35b, 37a, 37b ... Actuator oil passage, 34, 36 ... Pressure oil supply oil passage, 41 ... Controller, 43a to 43d , 44a to 44d, 45a to 45d, 46a to 46d, 47a to 47d, 48a to 48d, 49a to 49d, 50a to 50d ... electromagnetic switching valve, 54, 55 ... control valve, 64 to 67 ... bleed-off valve, 70 ... Hydraulic valve block, 100 ... hydraulic excavator, 101 ... lower traveling body, 101a, 101b ... traveling device, 102 ... upper turning body, 102a ... turning device, 103 ... front device, 104 ... turning frame, 104a ... left frame, 104b ... Right frame, 104c ... Center frame, 105 ... Counterweight, 106 ... , 107 ... the left engine room, 108 ... right engine room, 109a ... left passage, 109b ... the right passage, 109c ... central passage.

Claims

A lower traveling body,
An upper revolving unit mounted on the lower traveling unit so as to be able to swivel;
A first device, a plurality of closed-circuit hydraulic pumps having two discharge ports, a plurality of hydraulic actuators, and a plurality of hydraulic actuators. The two switching ports of the plurality of hydraulic pumps are selectively used for at least some of the plurality of hydraulic actuators by selectively switching the plurality of electromagnetic switching valves to a communication position. In a construction machine including a hydraulic closed circuit system that is connected to and forms a closed circuit between the plurality of hydraulic pumps and at least some of the plurality of hydraulic actuators,
The hydraulic closed circuit system further comprises a second prime mover,
The plurality of hydraulic pumps include at least four hydraulic pumps, and the at least four hydraulic pumps include a hydraulic pump driven by the first prime mover and a hydraulic pump driven by the second prime mover,
At least four of the hydraulic pumps, when the plurality of electromagnetic switching valves are selectively switched to the communication position, discharge oil from one of the two discharge ports on the upstream side of the plurality of electromagnetic switching valves. A construction machine characterized by having a connection structure in which two pumps are joined together and the joined pressure oil is supplied to the plurality of electromagnetic switching valves.
The construction machine according to claim 1,
The four hydraulic pumps have two hydraulic pumps driven by the first prime mover and two hydraulic pumps driven by the second prime mover,
Discharged oil is merged by two hydraulic pumps, one included in each of two hydraulic pumps driven by the first prime mover and two hydraulic pumps driven by the second prime mover. Construction machinery.
The construction machine according to claim 1,
The four hydraulic pumps have two hydraulic pumps driven by the first prime mover and two hydraulic pumps driven by the second prime mover,
A construction machine characterized in that the discharge oil is merged by two hydraulic pumps driven by the first prime mover and the discharge oil is merged by two hydraulic pumps driven by the second prime mover.
The construction machine according to claim 1,
The upper swing body includes a swing frame as a foundation lower structure,
The swivel frame has a center frame, a left frame fastened to the left side of the center frame, and a left frame fastened to the right side of the center frame,
The first prime mover is disposed in a first machine room provided on the left frame,
The second prime mover is disposed in a second machine room provided on the right frame,
The four hydraulic pumps are arranged in the first machine room and driven by the first prime mover, and two hydraulic pumps are arranged in the second machine room and driven by the second prime mover. A hydraulic pump,
The construction machine, wherein the plurality of electromagnetic switching valves are arranged on the center frame and between the first and second machine rooms.