JP2009264109A - Work vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce noise and vibration in a work vehicle mounted with a hydraulically driven operating machine. <P>SOLUTION: A double gear pump 32 for forcibly feeding hydraulic fluid by engagement/rotation of a pair of gears composed of a drive gear and a driven gear mutually engaged includes two pairs of gears. The two pairs are configured in such a manner that pulsations of forcibly feeding operation of the hydraulic fluid are mutually shifted (ideally, a half cycle), thereby offsetting pulsations and suppressing vibration generation. A flow regulator 33 arranged in a hydraulic fluid passage 41 connecting the gear pump to the operating machine returns a part of hydraulic fluid to a hydraulic fluid tank 31 through a return hydraulic fluid passage 43 so that hydraulic pressure in the hydraulic fluid passage does not exceed a predetermined value. Thereby, it is possible to suppress an increase in engine speed for the purpose of increasing the speed of the operating machine by an operator, suppress the vibration level of each portion, and reduce noise and vibration. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a work vehicle equipped with a hydraulically driven work machine.

  At present, various work vehicles are used. Here, the work vehicle is a vehicle in which a work machine is mounted on the vehicle and work (excluding traveling of the vehicle) is performed by the work machine. As introduced in the following examples of garbage collection vehicles, work vehicles equipped with hydraulically driven work machines are widely used.

  Conventionally, a garbage truck 1 having a rotary conveyor panel (rotating plate) 2 and a swinging ram panel (pushing plate) 3 as shown in FIG. 7 is used. The conveyor panel 2 is driven by a hydraulic motor 4. The ram panel 3 is driven by a hydraulic cylinder 5. The garbage truck 1 is equipped with a hydraulic pump as a drive source in a hydraulic circuit that drives the hydraulic motor 4 and the hydraulic cylinder 5.

The following three methods are known as drive methods for the hydraulic pump.
The garbage truck 1a shown in FIG. 8 employs the PTO method.
The garbage collection vehicle 1a operates the vehicle drive engine 25 and then turns on a PTO (Power Take Off) device 6 for turning on the vehicle drive engine or the like. Power is taken out from the engine 25 and the hydraulic pump 7 is rotated by this power to generate a flow of hydraulic oil in the hydraulic circuit.
The garbage truck 1b shown in FIGS. 9 and 10 employs an electric drive type. The garbage collection vehicle 1b controls an inverter 9 using a battery 8 mounted as a power source to drive an electric motor 10, and transmits the rotation of the electric motor 10 to the hydraulic pump 7 to rotate the hydraulic pump 7, thereby rotating the hydraulic circuit. Generates a flow of hydraulic oil inside.

Furthermore, there is a system provided with both an engine drive system and an electric drive system as a rotational drive system of the hydraulic pump. Such a method is described in Patent Documents 1 to 4.
Patent Documents 1 and 2 describe a configuration block diagram in which an engine / PTO device system and a battery / electric motor system are described as a rotational drive system of a hydraulic pump. As a specific configuration, Patent Document 1 describes a configuration in which a PTO device is connected to a rotating shaft of a mechanical configuration in which an electric motor is integrated on the outer periphery of a hydraulic pump.
Patent Document 3 describes a configuration diagram in which a drive shaft driven by an engine is connected to a hydraulic pump. According to this configuration diagram, an electric drive system is also connected to the hydraulic pump. Patent Document 4 describes a configuration in which an engine, a generator motor, and a hydraulic pump are connected in this order. In the configurations described in Patent Documents 3 and 4, no PTO device is used.

  In any system, the pressure oil generated by the rotation of the hydraulic pump 7 drives the hydraulic motor 4 and the hydraulic cylinder 5 to operate the conveyor panel 2 and the ram panel 3 to perform work operations such as dust loading. For this purpose, the waste collection vehicle 1 changes the flow of hydraulic oil by switching the control valve (three-position both solenoid type, etc.) in the hydraulic circuit by an electric signal or the like, and the hydraulic actuators such as the hydraulic motor 4 and the hydraulic cylinder 5 operate. To control.

When the hydraulic pump 7 is driven, including when the panels 2 and 3 are not operating, there is a problem that noise due to the flow of hydraulic oil is large.
In recent years, garbage collection at night and early morning has been on the rise in order to alleviate the problem of litter station scattering due to congestion reduction and crows. Along with this, the number of noise complaints from neighboring residents due to garbage collection at night and early morning has increased.
As means for solving such a problem, in order to reduce the noise of the pump, various proposals have conventionally been made to mount various pumps on a garbage truck, but the conventionally proposed method has advantages and disadvantages and is decisively advantageous. No pump has been proposed.
An example of a pump that has already been proposed is shown below for reference.

The external gear pump is widely used because it is simple in structure, hard to break, and inexpensive and compact. However, since the gear meshing noise and discharge pulsation are large, the noise is loud.
The internal gear pump does not have a meshing sound like the external gear pump and is low noise. However, since the high speed rotation is necessary, the use environment is limited. In addition, since the internal gear pump is large in size, it is difficult to mount the internal gear pump inside the chassis frame of a 2t truck, and it is not popular in garbage trucks in Japan.
Piston pumps are based on the extrusion of oil from the top and bottom of the piston and are somewhat low noise. However, the structure is complex and the number of parts is high, so the price is generally high and the size is large.

In garbage trucks, the operator wants to increase the working speed of the machine, so the act of deliberately increasing the engine speed and increasing the pump operating speed is sometimes performed. Had a problem. When a plunger pump (plunger pump is classified as a piston pump) is used for the garbage truck, the plunger pump has the function of returning the hydraulic oil to the tank even if it is driven to rotate at a certain speed or higher. Since the working speed does not increase any more, the above action is suppressed.
Therefore, it has been known that the use of a plunger pump in a garbage collection vehicle can secure a relatively low noise and can prevent the above action.
On the other hand, in the case of a gear pump, a double pump gear is provided in which low noise and low vibration are realized by canceling pulsation between two pairs of gears.
Japanese Patent Laid-Open No. 10-37904 JP 2003-146600 A Japanese Patent Laid-Open No. 10-42587 JP 2004-150307 A

  The present invention has been made in view of the above problems in the prior art, and an object thereof is to reduce noise and vibration in a work vehicle equipped with a hydraulically driven work machine.

The invention according to claim 1 for solving the above-described problems includes a gear pump,
A working machine driven by hydraulic oil pumped by the gear pump,
The gear pump is a system that pumps hydraulic oil by meshing rotation of a gear pair composed of a drive gear and a driven gear that mesh with each other, and has two pairs of the gear pairs. It is configured so that the pulsations deviate from each other,
The gear pump pumps hydraulic oil in a hydraulic oil tank,
A valve installed in an ascending hydraulic oil passage connecting the gear pump and the work machine;
A branch hydraulic oil path branched from the upstream hydraulic oil path by the valve and connected to the hydraulic oil tank;
The valve is a work vehicle that returns part of the hydraulic oil to the hydraulic oil tank via the downward hydraulic oil passage.

The invention according to claim 2 is a flow regulator installed in the upstream hydraulic oil path,
A branch hydraulic oil path branched from the upstream hydraulic oil path with the flow regulator and connected to the hydraulic oil tank;
2. The work vehicle according to claim 1, wherein the flow regulator returns a part of the hydraulic oil to the hydraulic oil tank through the reverse hydraulic oil path so that the hydraulic pressure in the upward hydraulic oil path does not exceed a predetermined value. is there.

  A third aspect of the present invention is the work vehicle according to the first or second aspect, further comprising an electric motor that drives the gear pump.

  According to the present invention, the gear pump can cancel part of the discharge pulsation of the hydraulic oil pumped by the gear pair with each other by the two gear pairs. In addition, according to the present invention, the hydraulic pressure in the hydraulic oil passage is suppressed within a predetermined value by the action of the flow regulator, so that the operator wants to increase the working speed of the machine, so that the rotational speed of the engine and pump is intentionally The act of raising is suppressed. Therefore, according to the present invention, there is an effect that the vibration level of each part is suppressed and noise and vibration can be reduced.

  An embodiment of the present invention will be described below with reference to the drawings. The following is one embodiment of the present invention and does not limit the present invention.

  FIG. 1 is a configuration block diagram of a hydraulic drive system mounted on a work vehicle according to an embodiment of the present invention. These are arranged in the order of a double gear pump 32, a flow regulator 33, and an electromagnetic valve 34 on an upward hydraulic oil passage 41 connected from the hydraulic oil tank 31 to the hydraulic actuator 35. The hydraulic oil path between the hydraulic oil tank 31 and the double gear pump 32 is 41a, and the hydraulic oil path between the double gear pump 32 and the flow regulator 33 is 41b. The hydraulic actuator 35 corresponds to the hydraulic motor 4 or the hydraulic cylinder 5 shown in FIG. A downward hydraulic oil passage 42 branched from the upward hydraulic oil passage 41 by the electromagnetic valve 34 is connected to the hydraulic oil tank 31. Further, a return hydraulic oil path 43 branched from the upstream hydraulic oil path 41 by the flow regulator 33 is connected to the hydraulic oil tank 31.

  The double gear pump 32 pumps the hydraulic oil in the hydraulic oil tank 31 to the electromagnetic valve 34 through the flow regulator 33. The controller 37 judges the signals from the sensors attached to the work machine and the operation switch 36 based on a predetermined control rule, controls the opening and closing of the electromagnetic valve 34, and controls the pressure of the hydraulic actuator 35. Thus, the operation of the hydraulic actuator 35 is controlled. For example, in the example shown in FIG. 7, the hydraulic motor 4 rotates the conveyor panel 2, and the hydraulic cylinder 5 swings the ram panel 3 to perform dust loading work. The hydraulic oil pressure-fed to the electromagnetic valve 34 is returned to the hydraulic oil tank 31 through the downward hydraulic oil passage 42 according to the control status of the electromagnetic valve 34.

  The double gear pump 32 is rotationally driven by a drive device. As this driving device, for example, the PTO device 6 shown in FIG. 8 or the electric motor 10 shown in FIG. 9 is applied.

The flow regulator 33 opens and closes a path on the side of the backward hydraulic oil path 43 so that the hydraulic pressure in the hydraulic oil path 41 b does not exceed a predetermined value, and a part of the hydraulic oil passes through the backward hydraulic oil path 43. Return to the tank.
Therefore, even when an engine as shown in FIG. 8 is applied as a drive source of the double gear pump 32, the operator increases the engine speed and increases the operating speed of the hydraulic actuator for the purpose of increasing the speed of the work machine. That is suppressed.

  FIG. 2 is a configuration block diagram of a hydraulic drive system mounted on a work vehicle according to a conventional example. Compared to the conventional example, the hydraulic drive system of the present embodiment is different in that a double gear pump 32, a flow regulator 33, and a return hydraulic oil path 43 are incorporated. The gear pump 38 shown in FIG. 2 is a single gear pump having a pair of gears for pumping hydraulic oil, whereas the double gear pump 32 applied to the present embodiment has two pairs of gears for pumping hydraulic oil. It is different in that it has.

The configuration of the double gear pump 32 will be described below. FIG. 3 is a schematic perspective transparent view of the double gear pump 32. FIG. 4 is a schematic diagram of the internal structure of the double gear pump 32.
The double gear pump 32 includes a drive shaft 32a, two drive gears 32b and 32c, a rotation support shaft 32d, two driven gears 32e and 32f, and a casing 32g. The drive shaft 32a is rotationally driven by the drive device described above. The two drive gears 32b and 32c are respectively fitted and fixed to the drive shaft 32a, and rotate together with the drive shaft 32a.
The rotation support shaft 32d is disposed in parallel with the drive shaft 32a. The two driven gears 32e and 32f are rotatably supported on the rotation support shaft 32d, respectively. The driven gear 32e meshes with the drive gear 32b. The driven gear 32f meshes with the drive gear 32c. The lengths in the axial direction of the four gears 32b, 32c, 32e, and 32f are equal.

FIG. 4 is a schematic diagram of the internal structure of the double gear pump 32 in which the outer shapes of the four gears 32b, 32c, 32e, and 32f are drawn on the cross section of the casing 32g perpendicular to the drive shaft 32a. As shown in FIG. 4, the fixed angle of the drive gear 32b and the fixed angle of the drive gear 32c are shifted by a half pitch of the teeth.
As shown in FIGS. 3 and 4, a cavity having a partial cylindrical inner surface covering four gears 32b, 32c, 32e, and 32f is formed in the casing 32g, and the cavity has a pitch of a gear pair. Openings are provided at both ends in the axial direction perpendicular to the bus bar. The hydraulic oil passage 41a is connected to one opening of the casing 32g, and the hydraulic oil passage 41b is connected to the other opening. The rotation direction of the gear pair for pumping the hydraulic oil to the hydraulic oil passage 41b is shown in FIGS. 3 and 4 by an arc arrow 32h. When the gear pair rotates in the direction indicated by the arc arrow 32h, the hydraulic oil supplied from the hydraulic oil passage 41a is confined between the gears 32b, 32c, 32e, and 32f and the inner surface of the partial cylinder of the casing 32g. It is sent to the oil passage 41b side. The flow path of the hydraulic oil at this time is indicated by an arrow 32k in FIGS.

  As shown in FIG. 4, the fixed angle of the drive gear 32b and the fixed angle of the drive gear 32c are shifted by a half pitch of the teeth. Therefore, the pulsation of the pumping operation by the gear pairs 32b and 32c and the pulsation of the pumping operation by the gear pairs 32e and 32f are shifted by a half cycle. As a result, the discharge amount of the hydraulic oil as a whole of the double gear pump 32 becomes constant, and the pulsations of the two pairs of gears cancel each other to realize low vibration and low noise.

The theory of pulsation cancellation will be described with reference to FIG. FIG. 5 (b1) is a perspective view illustrating the drive shaft 32a and the two drive gears 32b and 32c of the double gear pump 32 of the present embodiment. The two drive gears 32b and 32c have the same axial length, and the length is L. FIG. 5 (a1) is a perspective view of the single gear pump with the drive shaft 52a and the drive gear 52b extracted. The single gear pump shown in FIG. 5 (a1) differs from the double gear pump 32 shown in FIG. 5 (b1) in that the axial length of the drive gear 52b is 2L, and the other specifications are the same. . For example, with such a configuration, a single gear pump and a double gear pump having the same capacity are compared. As an ideal case, when the discharge pulsation of the single gear pump appears in the waveform a shown in FIG. 5 (a2), the discharge pulsation of one gear pair of the double gear pump appears in the waveform a1 shown in FIG. 5 (b2), and the other The discharge pulsation of the gear pair appears as a waveform a2. As shown in FIGS. 5A2 and 5B2, the amplitudes of the waveform a1 and the waveform a2 are half of the amplitude of the waveform a. As shown in FIG. 5 (b2), the waveform a1 and the waveform a2 have the same amplitude and cycle, and the phases are shifted by a half cycle. Therefore, the amount of hydraulic oil discharged to the hydraulic oil passage 41b is constant by compensating the discharge amount of one gear pair that changes pulsation and the discharge amount of the other gear pair that changes pulsation with a half-cycle shift. In this way, the pulsation of one gear pair and the pulsation of the other gear pair cancel each other and become zero as in the composite wave b, and the discharge pulsation disappears. Therefore, the vibration caused by the discharge pulsation is transmitted to the surroundings. Not.
The double gear pump 32 applied to the present embodiment based on the theory described above realizes low vibration and low noise.

Next, a measurement result of noise performed by the present invention will be disclosed.
As an example of the present invention, it is assumed that the hydraulic drive system shown in FIG. 1 is applied, and the garbage collecting vehicle adopts the electric motor drive shown in FIG. Two comparative examples 1 and 2 were adopted as comparative examples. Comparative Examples 1 and 2 are garbage trucks to which the hydraulic drive system shown in FIG. 2 employing a single gear pump is applied. Comparative Example 1 employs the PTO drive shown in FIG. 8, and Comparative Example 2 employs the electric motor drive shown in FIG. While performing the loading operation (the same operation of the panels 2 and 3) under the same conditions by the dust collection vehicles of the present invention example and Comparative Examples 1 and 2, the noise value was measured by a measuring instrument at a position 5 m behind each dust collection vehicle. Measured. Regarding the inventive example and the comparative example 2, the measurement was performed with the engine stopped. The graph c shown in FIG. 6 is the noise measurement result of the present invention example, the graph d1 is the noise measurement result of the comparative example 1, and the graph d2 is the noise measurement result of the comparative example 2.

  As can be seen from the measurement results shown in FIG. 6, according to the example of the present invention, a decrease in the noise value was recognized for both the comparative example 1 of the PTO drive and the comparative example 2 of the electric motor drive. . Therefore, it is recognized that the application of the present invention has the effect of reducing noise.

In addition to contributing to noise problems, the following advantages also arise. Conventionally, as a countermeasure against vibration of the hydraulic oil piping and controller 37, these fixing structures are provided with vibration-proof rubber, or the controller 37 has a high substrate. There was a cost, such as customizing a rigid one. This was necessary to prevent destruction and malfunction of the controller 37. However, since the generated vibration is reduced by the application of the present invention, it is possible to simplify the anti-vibration measures that have been applied conventionally and to reduce the cost.

  In the above-described embodiment of the present invention, the flow regulator 33 and the hydraulic oil passage 43 are applied. However, the present invention is not limited to the configuration to which these are applied. In contrast to the configuration shown in FIG. You may implement this invention with the form which applied this.

1 is a configuration block diagram of a hydraulic drive system mounted on a work vehicle according to an embodiment of the present invention. It is a block diagram of the configuration of a hydraulic drive system mounted on a work vehicle according to a conventional example. It is a typical perspective transparent view of the double gear pump concerning one embodiment of the present invention. It is an internal structure schematic diagram of the double gear pump which concerns on one Embodiment of this invention. (a1) is the perspective view which extracted and drew the drive shaft and drive gear of a single gear pump. (b1) is the perspective view which extracted and drew the drive shaft and two drive gears of a double gear pump concerning one embodiment of the present invention. (a2) is a waveform showing the discharge pulsation of the single gear pump. (b2) is a waveform showing the discharge pulsation of the double gear pump. It is a graph which shows the noise measurement result of the example of the present invention and comparative examples 1 and 2. It is a perspective view which shows a refuse collection vehicle. It is a schematic plan view which shows a PTO type garbage truck. It is a schematic plan view which shows an electrically driven garbage collection vehicle. It is a left view which shows an electrically driven garbage collection vehicle.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Garbage truck 1a Garbage truck 1b Garbage truck 2 Conveyor panel 3 Ram panel 4 Hydraulic motor 5 Hydraulic cylinder 6 PTO device 7 Hydraulic pump 8 Battery 9 Inverter 10 Electric motor 25 Engine 31 Hydraulic oil tank 32 Double gear pump 32a Drive shaft 32b, 32c drive gear 32d rotation support shaft 32e, 32f driven gear 32g casing 33 flow regulator 34 electromagnetic valve 35 hydraulic actuator 36 sensor and switch 37 controller 38 gear pump 41 upstream hydraulic oil path 42 downward hydraulic oil path 43 reverse hydraulic oil path 52a drive shaft 52b Drive gear

Claims (3)

A gear pump,
A working machine driven by hydraulic oil pumped by the gear pump,
The gear pump is a system that pumps hydraulic oil by meshing rotation of a gear pair composed of a drive gear and a driven gear that mesh with each other, and has two pairs of the gear pairs. It is configured so that the pulsations deviate from each other,
The gear pump pumps hydraulic oil in a hydraulic oil tank,
A valve installed in an ascending hydraulic oil passage connecting the gear pump and the work machine;
A branch hydraulic oil path branched from the upstream hydraulic oil path by the valve and connected to the hydraulic oil tank;
The valve is a work vehicle that returns part of the hydraulic oil to the hydraulic oil tank via the downward hydraulic oil passage. A flow regulator installed in the upstream hydraulic oil passage;
A branch hydraulic oil path branched from the upstream hydraulic oil path with the flow regulator and connected to the hydraulic oil tank;
2. The work vehicle according to claim 1, wherein the flow regulator returns a part of the hydraulic oil to the hydraulic oil tank via the reverse hydraulic oil path so that the hydraulic pressure in the upward hydraulic oil path does not exceed a predetermined value.   The work vehicle according to claim 1, further comprising an electric motor that drives the gear pump.

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